-
Notifications
You must be signed in to change notification settings - Fork 1
Expand file tree
/
Copy pathpython3_crash2.html
More file actions
582 lines (513 loc) · 56.5 KB
/
python3_crash2.html
File metadata and controls
582 lines (513 loc) · 56.5 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
<!DOCTYPE html>
<html lang="cn">
<head>
<meta charset="utf-8" />
<title>[雪峰磁针石博客]python3快速入门教程1 turtle绘图-2函数</title>
<link rel="stylesheet" href="/theme/css/main.css" />
</head>
<body id="index" class="home">
<header id="banner" class="body">
<h1><a href="/">python自动化测试人工智能 </a></h1>
<nav><ul>
<li><a href="/category/ba-zi.html">八字</a></li>
<li><a href="/category/ce-shi.html">测试</a></li>
<li><a href="/category/ce-shi-kuang-jia.html">测试框架</a></li>
<li><a href="/category/common.html">common</a></li>
<li><a href="/category/da-shu-ju.html">大数据</a></li>
<li><a href="/category/feng-shui.html">风水</a></li>
<li><a href="/category/ji-qi-xue-xi.html">机器学习</a></li>
<li><a href="/category/jie-meng.html">解梦</a></li>
<li><a href="/category/linux.html">linux</a></li>
<li class="active"><a href="/category/python.html">python</a></li>
<li><a href="/category/shu-ji.html">书籍</a></li>
<li><a href="/category/shu-ju-fen-xi.html">数据分析</a></li>
<li><a href="/category/zhong-cao-yao.html">中草药</a></li>
<li><a href="/category/zhong-yi.html">中医</a></li>
</ul></nav>
</header><!-- /#banner -->
<section id="content" class="body">
<article>
<header>
<h1 class="entry-title">
<a href="/python3_crash2.html" rel="bookmark"
title="Permalink to [雪峰磁针石博客]python3快速入门教程1 turtle绘图-2函数">[雪峰磁针石博客]python3快速入门教程1 turtle绘图-2函数</a></h1>
</header>
<div class="entry-content">
<footer class="post-info">
<abbr class="published" title="2018-08-20T12:20:00+08:00">
Published: 一 20 八月 2018
</abbr>
<address class="vcard author">
By <a class="url fn" href="/author/andrew.html">andrew</a>
</address>
<p>In <a href="/category/python.html">python</a>.</p>
</footer><!-- /.post-info --> <h2 id="_1">菲波那契序列:</h2>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="c1"># Fibonacci series:</span>
<span class="o">...</span> <span class="c1"># the sum of two elements defines the next</span>
<span class="o">...</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span>
<span class="o">>>></span> <span class="k">while</span> <span class="n">b</span> <span class="o"><</span> <span class="mi">10</span><span class="p">:</span>
<span class="o">...</span> <span class="k">print</span><span class="p">(</span><span class="n">b</span><span class="p">)</span>
<span class="o">...</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="n">b</span><span class="p">,</span> <span class="n">a</span><span class="o">+</span><span class="n">b</span>
<span class="o">...</span>
<span class="mi">1</span>
<span class="mi">1</span>
<span class="mi">2</span>
<span class="mi">3</span>
<span class="mi">5</span>
<span class="mi">8</span>
</pre></div>
<p>本例的新特性。</p>
<ul>
<li>
<p>第一行和最后一行有多赋值：第一行变量a和b同时获得了新的值0和1。最后一行右边首先完成计算，右边的表达式从左到右计算。</p>
</li>
<li>
<p>条件(b < 10)为true时while循环执行。这里Python类似C ，任何非零整数都为true；0为 false。判断条件也可以是字符串或列表等序列；所有长度不为零的为true ，空序列为false。示例中的测试是一个简单的比较。标准比较操作符与C相同： <(小于)， >(大于)， ==(等于)，<=(小于等于)，>=(大于等于)和!=(不等于)。</p>
</li>
<li>
<p>循环体需要缩进：缩进是Python组织语句的方法。在命令行下，缩进行需要插入空格或者tab。建议使用文本编辑 或者IDE，一般都提供自动缩进。命令行输入复合语句时，必须用空行来标识结束（因为解释器没办法猜识别最后一行），注意同一级的语句需要缩进同样数量的空白。建议使用空格而不是tab缩进。</p>
</li>
<li>
<p>print语句输出表达式的值。字符串打印时没有引号，每两个项目之间有空格。</p>
</li>
</ul>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">i</span> <span class="o">=</span> <span class="mi">256</span><span class="o">*</span><span class="mi">256</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="s1">'The value of i is'</span><span class="p">,</span> <span class="n">i</span><span class="p">)</span>
<span class="n">The</span> <span class="n">value</span> <span class="n">of</span> <span class="n">i</span> <span class="ow">is</span> <span class="mi">65536</span>
</pre></div>
<p>逗号结尾就可以避免输出换行:</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span>
<span class="o">>>></span> <span class="k">while</span> <span class="n">b</span> <span class="o"><</span> <span class="mi">1000</span><span class="p">:</span>
<span class="o">...</span> <span class="k">print</span><span class="p">(</span><span class="n">b</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s1">','</span><span class="p">)</span>
<span class="o">...</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="n">b</span><span class="p">,</span> <span class="n">a</span><span class="o">+</span><span class="n">b</span>
<span class="o">...</span>
<span class="mi">1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">21</span><span class="p">,</span><span class="mi">34</span><span class="p">,</span><span class="mi">55</span><span class="p">,</span><span class="mi">89</span><span class="p">,</span><span class="mi">144</span><span class="p">,</span><span class="mi">233</span><span class="p">,</span><span class="mi">377</span><span class="p">,</span><span class="mi">610</span><span class="p">,</span><span class="mi">987</span><span class="p">,</span>
</pre></div>
<h2 id="_2">定义函数</h2>
<p>菲波那契数列的函数:</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="k">def</span> <span class="nf">fib</span><span class="p">(</span><span class="n">n</span><span class="p">):</span> <span class="c1"># write Fibonacci series up to n</span>
<span class="o">...</span> <span class="s2">"""Print a Fibonacci series up to n."""</span>
<span class="o">...</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span>
<span class="o">...</span> <span class="k">while</span> <span class="n">a</span> <span class="o"><</span> <span class="n">n</span><span class="p">:</span>
<span class="o">...</span> <span class="k">print</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s1">' '</span><span class="p">)</span>
<span class="o">...</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="n">b</span><span class="p">,</span> <span class="n">a</span><span class="o">+</span><span class="n">b</span>
<span class="o">...</span> <span class="k">print</span><span class="p">()</span>
<span class="o">...</span>
<span class="o">>>></span> <span class="c1"># Now call the function we just defined:</span>
<span class="o">...</span> <span class="n">fib</span><span class="p">(</span><span class="mi">2000</span><span class="p">)</span>
<span class="mi">0</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mi">2</span> <span class="mi">3</span> <span class="mi">5</span> <span class="mi">8</span> <span class="mi">13</span> <span class="mi">21</span> <span class="mi">34</span> <span class="mi">55</span> <span class="mi">89</span> <span class="mi">144</span> <span class="mi">233</span> <span class="mi">377</span> <span class="mi">610</span> <span class="mi">987</span> <span class="mi">1597</span>
</pre></div>
<p>关键字def引入函数定义，其后有函数名和包含在圆括号中的形式参数。函数体语句从下一行开始，必须缩进的。<br>
函数体的第一行语句可以是可选的字符串文本，即文档字符串。有些工具通过docstrings 自动生成文档，或者让用户通过代码交互浏览；添加文档字符串是个很好的习惯。<br>
函数执行时生成符号表用来存储局部变量。 确切地说，所有函数的变量赋值都存储在局部符号表。 变量查找的顺序，先局部，然后逐级向上，再到全局变量，最后内置名。全局变量可在局部直接引用，但不能直接赋值(除非用global声明)，尽管他们可以被引用, 因为python在局部赋值会重新定义一个本地变量。</p>
<p>函数的实际参数在调用时引入局部符号表，也就是说是传值调用(值总是对象引用, 而不是该对象的值)。<br>
函数定义会在当前符号表内引入函数名。 函数名的值为用户自定义函数的类型,这个值可以赋值给其他变量当做函数别名使用。</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">fib</span>
<span class="o"><</span><span class="n">function</span> <span class="n">fib</span> <span class="n">at</span> <span class="mi">10042</span><span class="n">ed0</span><span class="o">></span>
<span class="o">>>></span> <span class="n">f</span> <span class="o">=</span> <span class="n">fib</span>
<span class="o">>>></span> <span class="n">f</span><span class="p">(</span><span class="mi">100</span><span class="p">)</span>
<span class="mi">0</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mi">2</span> <span class="mi">3</span> <span class="mi">5</span> <span class="mi">8</span> <span class="mi">13</span> <span class="mi">21</span> <span class="mi">34</span> <span class="mi">55</span> <span class="mi">89</span>
</pre></div>
<p>没有return语句的函数也会返回None。 解释器一般不会显示None，除非用print打印。</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">fib</span>
<span class="o"><</span><span class="n">function</span> <span class="n">fib</span> <span class="n">at</span> <span class="mi">10042</span><span class="n">ed0</span><span class="o">></span>
<span class="o">>>></span> <span class="n">f</span> <span class="o">=</span> <span class="n">fib</span>
<span class="o">>>></span> <span class="n">f</span><span class="p">(</span><span class="mi">100</span><span class="p">)</span>
<span class="mi">0</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mi">2</span> <span class="mi">3</span> <span class="mi">5</span> <span class="mi">8</span> <span class="mi">13</span> <span class="mi">21</span> <span class="mi">34</span> <span class="mi">55</span> <span class="mi">89</span>
</pre></div>
<p>从函数中返回</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="k">def</span> <span class="nf">fib2</span><span class="p">(</span><span class="n">n</span><span class="p">):</span> <span class="c1"># return Fibonacci series up to n</span>
<span class="o">...</span> <span class="s2">"""Return a list containing the Fibonacci series up to n."""</span>
<span class="o">...</span> <span class="n">result</span> <span class="o">=</span> <span class="p">[]</span>
<span class="o">...</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span>
<span class="o">...</span> <span class="k">while</span> <span class="n">a</span> <span class="o"><</span> <span class="n">n</span><span class="p">:</span>
<span class="o">...</span> <span class="n">result</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">a</span><span class="p">)</span> <span class="c1"># see below</span>
<span class="o">...</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">=</span> <span class="n">b</span><span class="p">,</span> <span class="n">a</span><span class="o">+</span><span class="n">b</span>
<span class="o">...</span> <span class="k">return</span> <span class="n">result</span>
<span class="o">...</span>
<span class="o">>>></span> <span class="n">f100</span> <span class="o">=</span> <span class="n">fib2</span><span class="p">(</span><span class="mi">100</span><span class="p">)</span> <span class="c1"># call it</span>
<span class="o">>>></span> <span class="n">f100</span> <span class="c1"># write the result</span>
<span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span> <span class="mi">8</span><span class="p">,</span> <span class="mi">13</span><span class="p">,</span> <span class="mi">21</span><span class="p">,</span> <span class="mi">34</span><span class="p">,</span> <span class="mi">55</span><span class="p">,</span> <span class="mi">89</span><span class="p">]</span>
</pre></div>
<p>return语句从函数中返回值，不带表达式的return返回None。过程结束后也会返回 None 。</p>
<p>语句result.append(b)称为调用了列表的方法。方法是属于对象的函数，如obj.methodename，obj 是个对象(可能是一个表达式)，methodname是对象的方法名。不同类型有不同的方法。不同类型可能有同名的方法。append()向链表尾部附加元素，等同于 result = result + [b] ，不过更有效。</p>
<h2 id="turtle">调用turtle库的函数</h2>
<p><img alt="image" src="https://oscimg.oschina.net/oscnet/22876b4dee0fb19333a14d17e3c2de0777b.jpg"></p>
<p>代码：</p>
<div class="highlight"><pre><span></span><span class="c1"># -*- coding: utf-8 -*-</span>
<span class="c1"># Author: xurongzhong#126.com wechat:pythontesting qq:37391319</span>
<span class="c1"># 技术支持 钉钉群：21745728(可以加钉钉pythontesting邀请加入) </span>
<span class="c1"># qq群：144081101 591302926 567351477</span>
<span class="c1"># CreateDate: 2018-6-12 </span>
<span class="c1"># bowtie.py</span>
<span class="c1"># Draw a bowtie</span>
<span class="kn">from</span> <span class="nn">turtle</span> <span class="kn">import</span> <span class="o">*</span>
<span class="n">pensize</span><span class="p">(</span><span class="mi">7</span><span class="p">)</span>
<span class="n">penup</span><span class="p">()</span>
<span class="n">goto</span><span class="p">(</span><span class="o">-</span><span class="mi">200</span><span class="p">,</span> <span class="o">-</span><span class="mi">100</span><span class="p">)</span>
<span class="n">pendown</span><span class="p">()</span>
<span class="n">fillcolor</span><span class="p">(</span><span class="s2">"red"</span><span class="p">)</span>
<span class="n">begin_fill</span><span class="p">()</span>
<span class="n">goto</span><span class="p">(</span><span class="o">-</span><span class="mi">200</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>
<span class="n">goto</span><span class="p">(</span><span class="mi">200</span><span class="p">,</span> <span class="o">-</span><span class="mi">100</span><span class="p">)</span>
<span class="n">goto</span><span class="p">(</span><span class="mi">200</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>
<span class="n">goto</span><span class="p">(</span><span class="o">-</span><span class="mi">200</span><span class="p">,</span> <span class="o">-</span><span class="mi">100</span><span class="p">)</span>
<span class="n">end_fill</span><span class="p">()</span>
<span class="n">exitonclick</span><span class="p">()</span>
</pre></div>
<table>
<thead>
<tr>
<th>方法</th>
<th>功能</th>
</tr>
</thead>
<tbody>
<tr>
<td>fgoto(x, y)</td>
<td>移到位置（x，y）。</td>
</tr>
<tr>
<td>pensize(width)</td>
<td>将笔绘制的线的粗细设置为width或返回当前值。</td>
</tr>
<tr>
<td>pencolor(color)</td>
<td>将笔颜色设置为color或返回当前值。</td>
</tr>
<tr>
<td>fillcolor(color)</td>
<td>将填充颜色设置为color或返回当前值。</td>
</tr>
<tr>
<td>color(color)</td>
<td>将笔和填充颜色设置为color或返回当前值。</td>
</tr>
<tr>
<td>begin_fill()</td>
<td>开始填充</td>
</tr>
<tr>
<td>end_fill()</td>
<td>结束填充</td>
</tr>
<tr>
<td>turtlesize(factor)</td>
<td>以factor拉伸。</td>
</tr>
<tr>
<td>showturtle()</td>
<td>开始显示。</td>
</tr>
<tr>
<td>hideturtle()</td>
<td>停止显示</td>
</tr>
</tbody>
</table>
<h2 id="_3">自己写画圆的函数</h2>
<p><img alt="image" src="https://oscimg.oschina.net/oscnet/3cd8689ee573540e14795d9f70e4c07a028.jpg"></p>
<p>代码：</p>
<div class="highlight"><pre><span></span><span class="c1"># -*- coding: utf-8 -*-</span>
<span class="c1"># Author: xurongzhong#126.com wechat:pythontesting qq:37391319</span>
<span class="c1"># 技术支持 钉钉群：21745728(可以加钉钉pythontesting邀请加入) </span>
<span class="c1"># qq群：144081101 591302926 567351477</span>
<span class="c1"># CreateDate: 2018-6-12 </span>
<span class="c1"># bowtie.py</span>
<span class="c1"># Draw a bowtie</span>
<span class="kn">from</span> <span class="nn">turtle</span> <span class="kn">import</span> <span class="o">*</span>
<span class="k">def</span> <span class="nf">circle_at</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">r</span><span class="p">):</span>
<span class="sd">"""Draw circle with center (x, y) radius r."""</span>
<span class="n">penup</span><span class="p">()</span>
<span class="n">goto</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span> <span class="o">-</span> <span class="n">r</span><span class="p">)</span>
<span class="n">pendown</span><span class="p">()</span>
<span class="n">setheading</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span>
<span class="n">circle</span><span class="p">(</span><span class="n">r</span><span class="p">)</span>
<span class="n">circle_at</span><span class="p">(</span><span class="o">-</span><span class="mi">200</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">20</span><span class="p">)</span>
<span class="n">begin_fill</span><span class="p">()</span>
<span class="n">circle_at</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>
<span class="n">end_fill</span><span class="p">()</span>
<span class="n">circle_at</span><span class="p">(</span><span class="mi">200</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">20</span><span class="p">)</span>
<span class="n">hideturtle</span><span class="p">()</span>
<span class="n">exitonclick</span><span class="p">()</span>
</pre></div>
<h2 id="python">深入Python函数定义</h2>
<p>python的函数参数有三种方式。</p>
<h3 id="_4">默认参数</h3>
<p>最常用的方式是给参数指定默认值，调用时就可以少传参数:</p>
<div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">ask_ok</span><span class="p">(</span><span class="n">prompt</span><span class="p">,</span> <span class="n">retries</span><span class="o">=</span><span class="mi">4</span><span class="p">,</span> <span class="n">reminder</span><span class="o">=</span><span class="s1">'Please try again!'</span><span class="p">):</span>
<span class="k">while</span> <span class="bp">True</span><span class="p">:</span>
<span class="n">ok</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="n">prompt</span><span class="p">)</span>
<span class="k">if</span> <span class="n">ok</span> <span class="ow">in</span> <span class="p">(</span><span class="s1">'y'</span><span class="p">,</span> <span class="s1">'ye'</span><span class="p">,</span> <span class="s1">'yes'</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">True</span>
<span class="k">if</span> <span class="n">ok</span> <span class="ow">in</span> <span class="p">(</span><span class="s1">'n'</span><span class="p">,</span> <span class="s1">'no'</span><span class="p">,</span> <span class="s1">'nop'</span><span class="p">,</span> <span class="s1">'nope'</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">False</span>
<span class="n">retries</span> <span class="o">=</span> <span class="n">retries</span> <span class="o">-</span> <span class="mi">1</span>
<span class="k">if</span> <span class="n">retries</span> <span class="o"><</span> <span class="mi">0</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'invalid user response'</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="n">reminder</span><span class="p">)</span>
</pre></div>
<p>调用方式:</p>
<p>只给出必选参数: ask_ok('Do you really want to quit?') 给出一个可选的参数: ask_ok('OK to overwrite the file?', 2)<br>
给出所有的参数: ask_ok('OK to overwrite the file?', 2, 'Come on, only yes or no!')</p>
<p>in关键字测定序列是否包含指定值。</p>
<p>默认值在函数定义时传入，如下所示:</p>
<div class="highlight"><pre><span></span><span class="n">i</span> <span class="o">=</span> <span class="mi">5</span>
<span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">arg</span><span class="o">=</span><span class="n">i</span><span class="p">):</span>
<span class="k">print</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span>
<span class="n">i</span> <span class="o">=</span> <span class="mi">6</span>
<span class="n">f</span><span class="p">()</span>
</pre></div>
<p>上例显示5。</p>
<p>注意: 默认值只赋值一次。当默认值是可变对象(比如列表、字典或者大多数类的实例)时结果会不同。实例：</p>
<div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">L</span><span class="o">=</span><span class="p">[]):</span>
<span class="n">L</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">a</span><span class="p">)</span>
<span class="k">return</span> <span class="n">L</span>
<span class="k">print</span> <span class="n">f</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
<span class="k">print</span> <span class="n">f</span><span class="p">(</span><span class="mi">2</span><span class="p">)</span>
<span class="k">print</span> <span class="n">f</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span>
<span class="c1"># 执行结果：</span>
<span class="p">[</span><span class="mi">1</span><span class="p">]</span>
<span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">]</span>
<span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">]</span>
</pre></div>
<p>规避方式：</p>
<div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">L</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="k">if</span> <span class="n">L</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">L</span> <span class="o">=</span> <span class="p">[]</span>
<span class="n">L</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">a</span><span class="p">)</span>
<span class="k">return</span> <span class="n">L</span>
</pre></div>
<h3 id="_5">关键字参数</h3>
<p>关键字参数 的形式: keyword = value。</p>
<div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">parrot</span><span class="p">(</span><span class="n">voltage</span><span class="p">,</span> <span class="n">state</span><span class="o">=</span><span class="s1">'a stiff'</span><span class="p">,</span> <span class="n">action</span><span class="o">=</span><span class="s1">'voom'</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="s1">'Norwegian Blue'</span><span class="p">):</span>
<span class="k">print</span><span class="p">(</span><span class="s2">"-- This parrot wouldn't"</span><span class="p">,</span> <span class="n">action</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s1">' '</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s2">"if you put"</span><span class="p">,</span> <span class="n">voltage</span><span class="p">,</span> <span class="s2">"volts through it."</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s2">"-- Lovely plumage, the"</span><span class="p">,</span> <span class="nb">type</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s2">"-- It's"</span><span class="p">,</span> <span class="n">state</span><span class="p">,</span> <span class="s2">"!"</span><span class="p">)</span>
</pre></div>
<p>有效调用：</p>
<div class="highlight"><pre><span></span><span class="n">parrot</span><span class="p">(</span><span class="mi">1000</span><span class="p">)</span> <span class="c1"># 1 positional argument</span>
<span class="n">parrot</span><span class="p">(</span><span class="n">voltage</span><span class="o">=</span><span class="mi">1000</span><span class="p">)</span> <span class="c1"># 1 keyword argument</span>
<span class="n">parrot</span><span class="p">(</span><span class="n">voltage</span><span class="o">=</span><span class="mi">1000000</span><span class="p">,</span> <span class="n">action</span><span class="o">=</span><span class="s1">'VOOOOOM'</span><span class="p">)</span> <span class="c1"># 2 keyword arguments</span>
<span class="n">parrot</span><span class="p">(</span><span class="n">action</span><span class="o">=</span><span class="s1">'VOOOOOM'</span><span class="p">,</span> <span class="n">voltage</span><span class="o">=</span><span class="mi">1000000</span><span class="p">)</span> <span class="c1"># 2 keyword arguments</span>
<span class="n">parrot</span><span class="p">(</span><span class="s1">'a million'</span><span class="p">,</span> <span class="s1">'bereft of life'</span><span class="p">,</span> <span class="s1">'jump'</span><span class="p">)</span> <span class="c1"># 3 positional arguments</span>
<span class="n">parrot</span><span class="p">(</span><span class="s1">'a thousand'</span><span class="p">,</span> <span class="n">state</span><span class="o">=</span><span class="s1">'pushing up the daisies'</span><span class="p">)</span> <span class="c1"># 1 positional, 1 keyword</span>
</pre></div>
<p>无效调用</p>
<div class="highlight"><pre><span></span><span class="n">parrot</span><span class="p">()</span> <span class="c1"># 没有必选参数</span>
<span class="n">parrot</span><span class="p">(</span><span class="n">voltage</span><span class="o">=</span><span class="mf">5.0</span><span class="p">,</span> <span class="s1">'dead'</span><span class="p">)</span> <span class="c1"># 关键参数后面有非关键字参数</span>
<span class="n">parrot</span><span class="p">(</span><span class="mi">110</span><span class="p">,</span> <span class="n">voltage</span><span class="o">=</span><span class="mi">220</span><span class="p">)</span> <span class="c1"># 同一参数重复指定值</span>
<span class="n">parrot</span><span class="p">(</span><span class="n">actor</span><span class="o">=</span><span class="s1">'John Cleese'</span><span class="p">)</span> <span class="c1"># 不正确的关键字参数名</span>
</pre></div>
<p>关键字参数在位置参数之后，多个关键字参数的顺序先后无关，一个参数只能指定一次值，报错实例：</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="k">def</span> <span class="nf">function</span><span class="p">(</span><span class="n">a</span><span class="p">):</span>
<span class="o">...</span> <span class="k">pass</span>
<span class="o">...</span>
<span class="o">>>></span> <span class="n">function</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="n">a</span><span class="o">=</span><span class="mi">0</span><span class="p">)</span>
<span class="n">Traceback</span> <span class="p">(</span><span class="n">most</span> <span class="n">recent</span> <span class="n">call</span> <span class="n">last</span><span class="p">):</span>
<span class="n">File</span> <span class="s2">"<stdin>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1</span><span class="p">,</span> <span class="ow">in</span> <span class="err">?</span>
<span class="ne">TypeError</span><span class="p">:</span> <span class="n">function</span><span class="p">()</span> <span class="n">got</span> <span class="n">multiple</span> <span class="n">values</span> <span class="k">for</span> <span class="n">keyword</span> <span class="n">argument</span> <span class="s1">'a'</span>
</pre></div>
<p>最后一个如果前有两个星号(比如name)接收一个字典，存储形式参数没有定义的参数名和值。类似的单个星号比如*name表示接受一个元组。</p>
<div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">cheeseshop</span><span class="p">(</span><span class="n">kind</span><span class="p">,</span> <span class="o">*</span><span class="n">arguments</span><span class="p">,</span> <span class="o">**</span><span class="n">keywords</span><span class="p">):</span>
<span class="k">print</span><span class="p">(</span><span class="s2">"-- Do you have any"</span><span class="p">,</span> <span class="n">kind</span><span class="p">,</span> <span class="s2">"?"</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s2">"-- I'm sorry, we're all out of"</span><span class="p">,</span> <span class="n">kind</span><span class="p">)</span>
<span class="k">for</span> <span class="n">arg</span> <span class="ow">in</span> <span class="n">arguments</span><span class="p">:</span>
<span class="k">print</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s2">"-"</span> <span class="o">*</span> <span class="mi">40</span><span class="p">)</span>
<span class="k">for</span> <span class="n">kw</span> <span class="ow">in</span> <span class="n">keywords</span><span class="p">:</span>
<span class="k">print</span><span class="p">(</span><span class="n">kw</span><span class="p">,</span> <span class="s2">":"</span><span class="p">,</span> <span class="n">keywords</span><span class="p">[</span><span class="n">kw</span><span class="p">])</span>
</pre></div>
<p>调用</p>
<div class="highlight"><pre><span></span><span class="n">cheeseshop</span><span class="p">(</span><span class="s2">"Limburger"</span><span class="p">,</span> <span class="s2">"It's very runny, sir."</span><span class="p">,</span>
<span class="s2">"It's really very, VERY runny, sir."</span><span class="p">,</span>
<span class="n">shopkeeper</span><span class="o">=</span><span class="s1">'Michael Palin'</span><span class="p">,</span>
<span class="n">client</span><span class="o">=</span><span class="s2">"John Cleese"</span><span class="p">,</span>
<span class="n">sketch</span><span class="o">=</span><span class="s2">"Cheese Shop Sketch"</span><span class="p">)</span>
</pre></div>
<p>执行：</p>
<div class="highlight"><pre><span></span><span class="o">--</span> <span class="n">Do</span> <span class="n">you</span> <span class="n">have</span> <span class="nb">any</span> <span class="n">Limburger</span> <span class="err">?</span>
<span class="o">--</span> <span class="n">I</span><span class="s1">'m sorry, we'</span><span class="n">re</span> <span class="nb">all</span> <span class="n">out</span> <span class="n">of</span> <span class="n">Limburger</span>
<span class="n">It</span><span class="s1">'s very runny, sir.</span>
<span class="n">It</span><span class="s1">'s really very, VERY runny, sir.</span>
<span class="o">----------------------------------------</span>
<span class="n">client</span> <span class="p">:</span> <span class="n">John</span> <span class="n">Cleese</span>
<span class="n">shopkeeper</span> <span class="p">:</span> <span class="n">Michael</span> <span class="n">Palin</span>
<span class="n">sketch</span> <span class="p">:</span> <span class="n">Cheese</span> <span class="n">Shop</span> <span class="n">Sketch</span>
</pre></div>
<p>注意参数顺序是随机的，可以使用sort排序。</p>
<h3 id="_6">任意参数列表</h3>
<div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">write_multiple_items</span><span class="p">(</span><span class="nb">file</span><span class="p">,</span> <span class="n">separator</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">):</span>
<span class="nb">file</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="n">separator</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">args</span><span class="p">))</span>
</pre></div>
<h3 id="_7">参数列表解包</h3>
<p>把列表或元组拆分成多个并列的参数。</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="nb">range</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span> <span class="mi">6</span><span class="p">)</span> <span class="c1"># normal call with separate arguments</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">5</span><span class="p">]</span>
<span class="o">>>></span> <span class="n">args</span> <span class="o">=</span> <span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">6</span><span class="p">]</span>
<span class="o">>>></span> <span class="nb">range</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">)</span> <span class="c1"># call with arguments unpacked from a list</span>
<span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">5</span><span class="p">]</span>
</pre></div>
<p>同样的字典可以用两个星号解包：</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="k">def</span> <span class="nf">parrot</span><span class="p">(</span><span class="n">voltage</span><span class="p">,</span> <span class="n">state</span><span class="o">=</span><span class="s1">'a stiff'</span><span class="p">,</span> <span class="n">action</span><span class="o">=</span><span class="s1">'voom'</span><span class="p">):</span>
<span class="o">...</span> <span class="k">print</span><span class="p">(</span><span class="s2">"-- This parrot wouldn't"</span><span class="p">,</span> <span class="n">action</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s1">' '</span><span class="p">)</span>
<span class="o">...</span> <span class="k">print</span><span class="p">(</span><span class="s2">"if you put"</span><span class="p">,</span> <span class="n">voltage</span><span class="p">,</span> <span class="s2">"volts through it."</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s1">' '</span><span class="p">)</span>
<span class="o">...</span> <span class="k">print</span><span class="p">(</span><span class="s2">"E's"</span><span class="p">,</span> <span class="n">state</span><span class="p">,</span> <span class="s2">"!"</span><span class="p">)</span>
<span class="o">...</span>
<span class="o">>>></span> <span class="n">d</span> <span class="o">=</span> <span class="p">{</span><span class="s2">"voltage"</span><span class="p">:</span> <span class="s2">"four million"</span><span class="p">,</span> <span class="s2">"state"</span><span class="p">:</span> <span class="s2">"bleedin' demised"</span><span class="p">,</span> <span class="s2">"action"</span><span class="p">:</span> <span class="s2">"VOOM"</span><span class="p">}</span>
<span class="o">>>></span> <span class="n">parrot</span><span class="p">(</span><span class="o">**</span><span class="n">d</span><span class="p">)</span>
<span class="o">--</span> <span class="n">This</span> <span class="n">parrot</span> <span class="n">wouldn</span><span class="s1">'t VOOM if you put four million volts through it. E'</span><span class="n">s</span> <span class="n">bleedin</span><span class="s1">' demised !</span>
</pre></div>
<h3 id="lambda">Lambda表达式</h3>
<p>lambda关键字可创建短小的匿名函数，函数体只有一行，创建时就可使用。比如求和：lambda a, b: a+b。通常不建议使用,不过在pandas等数据分析库广泛使用。</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="k">def</span> <span class="nf">make_incrementor</span><span class="p">(</span><span class="n">n</span><span class="p">):</span>
<span class="o">...</span> <span class="k">return</span> <span class="k">lambda</span> <span class="n">x</span><span class="p">:</span> <span class="n">x</span> <span class="o">+</span> <span class="n">n</span>
<span class="o">...</span>
<span class="o">>>></span> <span class="n">f</span> <span class="o">=</span> <span class="n">make_incrementor</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
<span class="o">>>></span> <span class="n">f</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span>
<span class="mi">42</span>
<span class="o">>>></span> <span class="n">f</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
<span class="mi">43</span>
</pre></div>
<p>除了返回表达式，lambda还可以用作函数参数。</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">pairs</span> <span class="o">=</span> <span class="p">[(</span><span class="mi">1</span><span class="p">,</span> <span class="s1">'one'</span><span class="p">),</span> <span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="s1">'two'</span><span class="p">),</span> <span class="p">(</span><span class="mi">3</span><span class="p">,</span> <span class="s1">'three'</span><span class="p">),</span> <span class="p">(</span><span class="mi">4</span><span class="p">,</span> <span class="s1">'four'</span><span class="p">)]</span>
<span class="o">>>></span> <span class="n">pairs</span><span class="o">.</span><span class="n">sort</span><span class="p">(</span><span class="n">key</span><span class="o">=</span><span class="k">lambda</span> <span class="n">pair</span><span class="p">:</span> <span class="n">pair</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span>
<span class="o">>>></span> <span class="n">pairs</span>
<span class="p">[(</span><span class="mi">4</span><span class="p">,</span> <span class="s1">'four'</span><span class="p">),</span> <span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s1">'one'</span><span class="p">),</span> <span class="p">(</span><span class="mi">3</span><span class="p">,</span> <span class="s1">'three'</span><span class="p">),</span> <span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="s1">'two'</span><span class="p">)](</span><span class="mi">1</span><span class="p">)</span>
</pre></div>
<h3 id="_8">文档字符串</h3>
<p>文档字符串的内容和格式建议如下。</p>
<p>第一简短介绍对象的目的。不能描述对象名和类型等其他地方能找到的信息，首字母要大写。<br>
如果文档字符串有多行，第二行为空行以分隔概述和其他描述。描述介绍调用约定、边界效应等。<br>
Python解释器不会从多行文档字符串中去除缩进，要用工具来处理。约定如下：第一行后的第一个非空行决定了整个文档的缩进。实例：</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="k">def</span> <span class="nf">my_function</span><span class="p">():</span>
<span class="o">...</span> <span class="s2">"""Do nothing, but document it.</span>
<span class="s2">...</span>
<span class="s2">... No, really, it doesn't do anything.</span>
<span class="s2">... """</span>
<span class="o">...</span> <span class="k">pass</span>
<span class="o">...</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="n">my_function</span><span class="o">.</span><span class="vm">__doc__</span><span class="p">)</span>
<span class="n">Do</span> <span class="n">nothing</span><span class="p">,</span> <span class="n">but</span> <span class="n">document</span> <span class="n">it</span><span class="o">.</span>
<span class="n">No</span><span class="p">,</span> <span class="n">really</span><span class="p">,</span> <span class="n">it</span> <span class="n">doesn</span><span class="s1">'t do anything.</span>
</pre></div>
<h2 id="_9">绘制人脸</h2>
<p><img alt="image" src="https://oscimg.oschina.net/oscnet/fe7c15f9fbd3c004a3e42d5b6b18d80a1b9.jpg"></p>
<p>代码：</p>
<div class="highlight"><pre><span></span><span class="c1"># -*- coding: utf-8 -*-</span>
<span class="c1"># Author: xurongzhong#126.com wechat:pythontesting qq:37391319</span>
<span class="c1"># 技术支持 钉钉群：21745728(可以加钉钉pythontesting邀请加入) </span>
<span class="c1"># qq群：144081101 591302926 567351477</span>
<span class="c1"># CreateDate: 2018-6-12 </span>
<span class="kn">from</span> <span class="nn">turtle</span> <span class="kn">import</span> <span class="o">*</span>
<span class="k">def</span> <span class="nf">circle_at</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">r</span><span class="p">):</span>
<span class="sd">"""Draw circle with center (x, y) radius r."""</span>
<span class="n">penup</span><span class="p">()</span>
<span class="n">goto</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span> <span class="o">-</span> <span class="n">r</span><span class="p">)</span>
<span class="n">pendown</span><span class="p">()</span>
<span class="n">setheading</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span>
<span class="n">circle</span><span class="p">(</span><span class="n">r</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">eye</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">radius</span><span class="p">):</span>
<span class="sd">"""Draw an eye centered at (x, y) of given radius."""</span>
<span class="n">circle_at</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">radius</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">face</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">width</span><span class="p">):</span>
<span class="sd">"""Draw face centered at (x, y) of given width."""</span>
<span class="n">circle_at</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">width</span><span class="o">/</span><span class="mi">2</span><span class="p">)</span>
<span class="n">eye</span><span class="p">(</span><span class="n">x</span> <span class="o">-</span> <span class="n">width</span><span class="o">/</span><span class="mi">6</span><span class="p">,</span> <span class="n">y</span> <span class="o">+</span> <span class="n">width</span><span class="o">/</span><span class="mi">5</span><span class="p">,</span> <span class="n">width</span><span class="o">/</span><span class="mi">12</span><span class="p">)</span>
<span class="n">eye</span><span class="p">(</span><span class="n">x</span> <span class="o">+</span> <span class="n">width</span><span class="o">/</span><span class="mi">6</span><span class="p">,</span> <span class="n">y</span> <span class="o">+</span> <span class="n">width</span><span class="o">/</span><span class="mi">5</span><span class="p">,</span> <span class="n">width</span><span class="o">/</span><span class="mi">12</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">main</span><span class="p">():</span>
<span class="n">face</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>
<span class="n">face</span><span class="p">(</span><span class="o">-</span><span class="mi">140</span><span class="p">,</span> <span class="mi">160</span><span class="p">,</span> <span class="mi">200</span><span class="p">)</span>
<span class="n">exitonclick</span><span class="p">()</span>
<span class="n">main</span><span class="p">()</span>
</pre></div>
<h2 id="_10">递归</h2>
<p>factorial.py</p>
<div class="highlight"><pre><span></span><span class="ch">#!/usr/bin/env python3</span>
<span class="c1"># -*- coding: utf-8 -*-</span>
<span class="c1"># Author: xurongzhong#126.com wechat:pythontesting qq:37391319</span>
<span class="c1"># qq群：144081101 591302926 567351477</span>
<span class="c1"># CreateDate: 2018-6-25</span>
<span class="c1"># factorial.py</span>
<span class="k">def</span> <span class="nf">factorial</span><span class="p">(</span><span class="n">n</span><span class="p">):</span>
<span class="sd">"""Return n! = 1*2*3*...*n."""</span>
<span class="k">if</span> <span class="n">n</span> <span class="o"><=</span> <span class="mi">1</span><span class="p">:</span>
<span class="k">return</span> <span class="mi">1</span>
<span class="k">return</span> <span class="n">n</span> <span class="o">*</span> <span class="n">factorial</span><span class="p">(</span><span class="n">n</span> <span class="o">-</span> <span class="mi">1</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">main</span><span class="p">():</span>
<span class="k">for</span> <span class="n">n</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">20</span><span class="p">):</span>
<span class="k">print</span><span class="p">(</span><span class="n">n</span><span class="p">,</span> <span class="n">factorial</span><span class="p">(</span><span class="n">n</span><span class="p">))</span>
<span class="k">print</span><span class="p">(</span><span class="n">factorial</span><span class="p">(</span><span class="mi">2000</span><span class="p">))</span>
<span class="n">main</span><span class="p">()</span>
</pre></div>
<p>执行结果</p>
<div class="highlight"><pre><span></span><span class="err">$</span> <span class="n">python3</span> <span class="n">factorial</span><span class="o">.</span><span class="n">py</span>
<span class="mi">0</span> <span class="mi">1</span>
<span class="mi">1</span> <span class="mi">1</span>
<span class="mi">2</span> <span class="mi">2</span>
<span class="mi">3</span> <span class="mi">6</span>
<span class="mi">4</span> <span class="mi">24</span>
<span class="mi">5</span> <span class="mi">120</span>
<span class="mi">6</span> <span class="mi">720</span>
<span class="mi">7</span> <span class="mi">5040</span>
<span class="mi">8</span> <span class="mi">40320</span>
<span class="mi">9</span> <span class="mi">362880</span>
<span class="mi">10</span> <span class="mi">3628800</span>
<span class="mi">11</span> <span class="mi">39916800</span>
<span class="mi">12</span> <span class="mi">479001600</span>
<span class="mi">13</span> <span class="mi">6227020800</span>
<span class="mi">14</span> <span class="mi">87178291200</span>
<span class="mi">15</span> <span class="mi">1307674368000</span>
<span class="mi">16</span> <span class="mi">20922789888000</span>
<span class="mi">17</span> <span class="mi">355687428096000</span>
<span class="mi">18</span> <span class="mi">6402373705728000</span>
<span class="mi">19</span> <span class="mi">121645100408832000</span>
<span class="n">Traceback</span> <span class="p">(</span><span class="n">most</span> <span class="n">recent</span> <span class="n">call</span> <span class="n">last</span><span class="p">):</span>
<span class="n">File</span> <span class="s2">"factorial.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">19</span><span class="p">,</span> <span class="ow">in</span> <span class="o"><</span><span class="n">module</span><span class="o">></span>
<span class="n">main</span><span class="p">()</span>
<span class="n">File</span> <span class="s2">"factorial.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">17</span><span class="p">,</span> <span class="ow">in</span> <span class="n">main</span>
<span class="k">print</span><span class="p">(</span><span class="n">factorial</span><span class="p">(</span><span class="mi">2000</span><span class="p">))</span>
<span class="n">File</span> <span class="s2">"factorial.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">12</span><span class="p">,</span> <span class="ow">in</span> <span class="n">factorial</span>
<span class="k">return</span> <span class="n">n</span> <span class="o">*</span> <span class="n">factorial</span><span class="p">(</span><span class="n">n</span> <span class="o">-</span> <span class="mi">1</span><span class="p">)</span>
<span class="n">File</span> <span class="s2">"factorial.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">12</span><span class="p">,</span> <span class="ow">in</span> <span class="n">factorial</span>
<span class="k">return</span> <span class="n">n</span> <span class="o">*</span> <span class="n">factorial</span><span class="p">(</span><span class="n">n</span> <span class="o">-</span> <span class="mi">1</span><span class="p">)</span>
<span class="n">File</span> <span class="s2">"factorial.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">12</span><span class="p">,</span> <span class="ow">in</span> <span class="n">factorial</span>
<span class="k">return</span> <span class="n">n</span> <span class="o">*</span> <span class="n">factorial</span><span class="p">(</span><span class="n">n</span> <span class="o">-</span> <span class="mi">1</span><span class="p">)</span>
<span class="p">[</span><span class="n">Previous</span> <span class="n">line</span> <span class="n">repeated</span> <span class="mi">993</span> <span class="n">more</span> <span class="n">times</span><span class="p">]</span>
<span class="n">File</span> <span class="s2">"factorial.py"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">10</span><span class="p">,</span> <span class="ow">in</span> <span class="n">factorial</span>
<span class="k">if</span> <span class="n">n</span> <span class="o"><=</span> <span class="mi">1</span><span class="p">:</span>
</pre></div>
<h2 id="_11">习题</h2>
<p>1，画出如下图形：</p>
<p><img alt="image" src="https://oscimg.oschina.net/oscnet/8242753de93f753c0154b3df274fafcde78.jpg"></p>
<h2 id="_12">参考资料</h2>
<ul>
<li>python测试等IT技术支持qq群： 144081101(后期会录制视频存在该群群文件) 591302926 567351477 钉钉免费群：21745728</li>
<li>道家技术-手相手诊看相中医等钉钉群21734177 qq群：391441566 184175668 338228106 看手相、面相、舌相、抽签、体质识别。服务费50元每人次起。请联系钉钉或者微信pythontesting</li>
<li><a href="https://china-testing.github.io/python3_crash2.html">本文最新版本地址</a></li>
<li><a href="https://github.com/china-testing/python-api-tesing">本文涉及的python测试开发库</a> 谢谢点赞！</li>
<li><a href="https://github.com/china-testing/python-api-tesing/blob/master/books.md">本文相关海量书籍下载</a></li>
<li><a href="https://china-testing.github.io/testing_training.html">接口自动化性能测试线上培训大纲</a></li>
</ul>
</div><!-- /.entry-content -->
</article>
</section>
<section id="extras" class="body">
<div class="blogroll">
<h2>links</h2>
<ul>
<li><a href="https://china-testing.github.io/testing_training.html">自动化性能接口测试线上及深圳培训与项目实战 qq群：144081101 591302926</a></li>
<li><a href="http://blog.sciencenet.cn/blog-2604609-1112306.html">pandas数据分析scrapy爬虫 521070358 Py人工智能pandas-opencv 6089740</a></li>
<li><a href="http://blog.sciencenet.cn/blog-2604609-1112306.html">中医解梦看相八字算命qq群 391441566 csdn书籍下载-python爬虫 437355848</a></li>
</ul>
</div><!-- /.blogroll -->
</section><!-- /#extras -->
<footer id="contentinfo" class="body">
<address id="about" class="vcard body">
Proudly powered by <a href="http://getpelican.com/">Pelican</a>, which takes great advantage of <a href="http://python.org">Python</a>.
</address><!-- /#about -->
<p>The theme is by <a href="http://coding.smashingmagazine.com/2009/08/04/designing-a-html-5-layout-from-scratch/">Smashing Magazine</a>, thanks!</p>
</footer><!-- /#contentinfo -->
</body>
</html>