Solutions to quizzy

entropy.cc

@@ -1,18 +1,49 @@
 #include <cmath>
 #include <iostream>
 #include <fstream>
+#include <algorithm>
 
 template <typename NumericType, int Discretization>
 NumericType entropy(const std::string& fileDescriptor) {
-  throw std::runtime_error("Implement me!");
+
+    std::ifstream ReadRandomData(fileDescriptor.c_str());
+    int NumberEvents = Discretization;
+    NumericType Events[NumberEvents];
+    for(int i = 0; i < NumberEvents-1; i++)
+    {
+        ReadRandomData >> Events[i];
+    }
+    NumericType* min_ptr = std::min_element(Events,Events+NumberEvents);
+    NumericType* max_ptr = std::max_element(Events,Events+NumberEvents);
+
+    NumericType min_value = *min_ptr;
+    NumericType max_value = *max_ptr;
+
+    int NumberBins = max_value - min_value + 1;
+
+    NumericType* Histogram = new NumericType [NumberBins];
+    for ( int i = 0; i < NumberEvents; i++ ) 
+    {
+      int idx = (int) ((Events[i] - min_value) / (ceil((max_value - min_value) / NumberBins) ));
+      Histogram[ idx ] ++;
+    }
+    NumericType entropy_val = 0;
+    for (int i = 0; i < NumberEvents; i++) 
+    {
+      NumericType prob = Histogram[i] * 1 / (float)NumberEvents;
+      entropy_val += -prob * log2(prob);
+    }
+    delete[] Histogram;
+    return entropy_val;
+
 }
 
 int main() {
   /*
    *Print out the entropy of a probability distribution over 8 discrete events,
    with event occurrences given by a random source of information. 
    */
-  //std::cout << entropy<float, 8>("/dev/random") << std::endl;
+    std::cout << entropy<float, 8>("random.txt") << std::endl;
   /*
    *Note: this is a suggested function signature, feel free to implement
    whatever you see fit!

matching.cc

@@ -22,17 +22,64 @@ constexpr std::array<std::array<float, kPatchSize>, kPatchSize> patchCandidate2
                                                                                      {0.03114041,0.15132543,0.60837695,0.18235618,0.74499181},
                                                                                      {0.19450344,0.93216069,0.5751807 ,0.38489764,0.5703268},
                                                                                      {0.92990664,0.22307124,0.63934838,0.38695049,0.21440734}}};
+
+float CalculateMean(std::array<std::array<float, kPatchSize>, kPatchSize> Patch)
+{
+    float sum = 0;
+    for (int i = 0; i < kPatchSize; i++)
+    {
+        for( int j = 0; j < kPatchSize; j++)
+        {
+            sum += Patch[i][j];
+        }
+    }
+    return sum / (kPatchSize*kPatchSize);
+}
+
+float CalculateSTD(std::array<std::array<float, kPatchSize>, kPatchSize> Patch)
+{
+    float sum = 0;
+    float mean = CalculateMean(Patch);
+    for (int i = 0; i < kPatchSize; i++)
+    {
+        for( int j = 0; j < kPatchSize; j++)
+        {
+            sum += (Patch[i][j]-mean)*(Patch[i][j]-mean);
+        }
+    }
+    return sqrt(sum/(kPatchSize*kPatchSize));
+}
+
+float similarity(std::array<std::array<float, kPatchSize>, kPatchSize> Patch1, std::array<std::array<float, kPatchSize>, kPatchSize> Patch2)
+{
+    float sum = 0;
+    float mean1 = CalculateMean(Patch1);
+    float mean2 = CalculateMean(Patch2);
+    float std1  = CalculateSTD(Patch1);
+    float std2  = CalculateSTD(Patch2);
+
+    for (int i = 0; i < kPatchSize; i++)
+    {
+        for( int j = 0; j < kPatchSize; j++)
+        {
+            sum += (Patch1[i][j]-mean1)*(Patch2[i][j]-mean2);
+        }
+    }
+    return (sum/(kPatchSize*kPatchSize*std1*std2));
+}
+
 int main() {
   /*
    *Print out the similarity between the reference patch, and candidate 1
    */
-  //std::cout << similarity(referencePatch, patchCandidate1) << std::endl;
+    std::cout << similarity(referencePatch, patchCandidate1) << std::endl;
   /*
    *Print out the similarity between the reference patch and candidate 2 
    */
-  //std::cout << similarity(referencePatch, patchCandidate2) << std::endl;
+    std::cout << similarity(referencePatch, patchCandidate2) << std::endl;
   /*
    *Note: this is a suggested function signature, feel free to implement
    whatever you see fit!
    */
+
 }

modeling.cc

@@ -25,6 +25,25 @@ constexpr std::array<std::array<float, kDimensions>, kDataPoints> points = {{{3.
                                                                              {3.0128605724511037, 1.8897446209038709},
                                                                              {1.9357873494944466, 2.9778798335036534}}};
 
+void ModelFit(float coeff[])
+{
+    float x = 0, y = 0, xy = 0, x2 = 0;
+    float mean_x = 0, mean_y = 0;
+    for(int i = 0; i < kDataPoints; i++)
+    {
+        x += points[i][0];
+        y += points[i][1];
+        xy += points[i][0] * points[i][1];
+        x2 += points[i][0] * points[i][0];
+    }
+    mean_x = x/kDataPoints;
+    mean_y = y/kDataPoints;
+    float ss_xy = xy - (kDataPoints*mean_x*mean_y);
+    float ss_x2 = x2 - (kDataPoints*mean_x*mean_x);
+    coeff[0] = ss_xy/ss_x2;
+    coeff[1] = mean_y - coeff[0]*mean_x;
+}
+
 
 int main() {
   /*
@@ -37,4 +56,8 @@ int main() {
    *Note: this is a suggested function signature, feel free to implement
    whatever you see fit!
    */
+  float coefficients[2];
+  ModelFit(coefficients);
+  std::cout <<"coefficients for the model: y = C0 + C1*x"<<std::endl;
+  std::cout <<"coefficient C0:"<<coefficients[1]<<"\n"<<"coefficient C1:"<<coefficients[0]<<std::endl; 
 }

random.txt

@@ -0,0 +1,9 @@
+1
+2
+3
+4
+5
+6
+7
+8
+

strings.cc

@@ -2,6 +2,21 @@
 #include <fstream>
 #include <vector>
 #include <assert.h>
+#include <string>
+
+using namespace std;
+int NumberOfPalindrome(std::string DictionaryPath)
+{
+    std::string test;
+    int count = 0;
+    ifstream ReadDict(DictionaryPath);
+    while(ReadDict >> test)
+    {
+       count += std::equal(test.begin(), test.begin() + test.size() / 2, test.rbegin()); 
+    }
+    return count;
+    ReadDict.close();
+}
 
 int main() {
   /*
@@ -20,4 +35,7 @@ int main() {
    *Note: this is a suggested function signature, feel free to implement
    whatever you see fit!
    */
+  std::string path = "words.txt";
+  int PalindromeCount = NumberOfPalindrome(path);
+  cout << "The number of palindromes in the dictionary are :"<<PalindromeCount<<endl;
 }

words.txt

@@ -0,0 +1,7 @@
+malayalam
+noon
+relax
+very
+cop
+pop
+