Add documentation and examples for group parameter in Table.hist (#641)

* docstring:added description of the group parameter to Table.hist

* tutorial: added example of using group parameter in hist

* Add 'group' example to hist section in datascience-reference

Author: KarevHero

datascience/tables.py

@@ -5285,7 +5285,8 @@ def hist(self, *columns, overlay=True, bins=None, bin_column=None, unit=None, co
                 grouped by the values in this column, and a separate histogram is
                 generated for each group.  The histograms are overlaid or plotted
                 separately depending on the overlay argument.  If None, no such
-                grouping is done.
+                grouping is done. Note: `group` cannot be used together with `bin_column` or when plotting
+                multiple columns. An error will be raised in these cases.
 
             side_by_side (bool): Whether histogram bins should be plotted side by
                 side (instead of directly overlaid).  Makes sense only when

docs/reference-nb/datascience-reference.ipynb

@@ -207,9 +207,7 @@
   {
    "cell_type": "code",
    "execution_count": 32,
-   "metadata": {
-    "scrolled": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -2194,7 +2192,9 @@
   {
    "cell_type": "code",
    "execution_count": 80,
-   "metadata": {},
+   "metadata": {
+    "scrolled": true
+   },
    "outputs": [
     {
      "data": {
@@ -2211,6 +2211,34 @@
     "actors.hist(\"Gross\")"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Using `group` with `Table.hist`\n",
+    "\n",
+    "You can also group the histogram by a categorical column using `group=`:\n",
+    "\n",
+    "The number of columns must be one, and you can't use `bin_column` with `group`."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "students = Table().with_columns(\n",
+    "    'Score', np.concatenate([\n",
+    "        np.random.normal(75, 10, 500),  # Group X: higher average score\n",
+    "        np.random.normal(65, 10, 500)   # Group Y: lower average score\n",
+    "    ]),\n",
+    "    'Group', ['X'] * 500 + ['Y'] * 500  # Assign 500 Xs and 500 Ys\n",
+    ")\n",
+    "\n",
+    "students.hist('Score', group='Group')  # Plot histogram grouped by 'Group'\n"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -4234,9 +4262,7 @@
   {
    "cell_type": "code",
    "execution_count": 100,
-   "metadata": {
-    "scrolled": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -4516,9 +4542,7 @@
   {
    "cell_type": "code",
    "execution_count": 112,
-   "metadata": {
-    "scrolled": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -6469,7 +6493,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
    "name": "python3"
   },
@@ -6483,9 +6507,9 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.1"
+   "version": "3.13.3"
   }
  },
  "nbformat": 4,
- "nbformat_minor": 2
-}
+ "nbformat_minor": 4
+}

docs/tutorial.rst

@@ -258,6 +258,19 @@ Draw histograms with :meth:`~datascience.tables.Table.hist`:
     @savefig hist_overlay.png width=4in
     normal_data.hist(bins = range(-5, 10), overlay = True)
 
+Draw grouped histograms with the ``group`` argument:
+
+.. ipython:: python
+
+    grouped = Table().with_columns(
+        'value', np.random.normal(size=100),
+        'group', np.random.choice(['A', 'B'], size=100)
+    )
+
+    @savefig hist_group.png width=4in
+    grouped.hist('value', group='group')
+Note: group cannot be used together with bin_column, and does not support multiple histogram columns.
+
 If we treat the ``normal_data`` table as a set of x-y points, we can
 :meth:`~datascience.tables.Table.plot` and
 :meth:`~datascience.tables.Table.scatter`: