DOC: Update the pandas.Series.str.count() docstring (Delhi) (#20154)

Author: Ridhwan Luthra

pandas/core/strings.py

@@ -212,15 +212,65 @@ def str_count(arr, pat, flags=0):
     """
     Count occurrences of pattern in each string of the Series/Index.
 
+    This function is used to count the number of times a particular regex
+    pattern is repeated in each of the string elements of the
+    :class:`~pandas.Series`.
+
     Parameters
     ----------
-    pat : string, valid regular expression
-    flags : int, default 0 (no flags)
-        re module flags, e.g. re.IGNORECASE
+    pat : str
+        Valid regular expression.
+    flags : int, default 0, meaning no flags
+        Flags for the `re` module. For a complete list, `see here
+        <https://docs.python.org/3/howto/regex.html#compilation-flags>`_.
+    **kwargs
+        For compatability with other string methods. Not used.
 
     Returns
     -------
-    counts : Series/Index of integer values
+    counts : Series or Index
+        Same type as the calling object containing the integer counts.
+
+    Notes
+    -----
+    Some characters need to be escaped when passing in `pat`.
+    eg. ``'$'`` has a special meaning in regex and must be escaped when
+    finding this literal character.
+
+    See Also
+    --------
+    re : Standard library module for regular expressions.
+    str.count : Standard library version, without regular expression support.
+
+    Examples
+    --------
+    >>> s = pd.Series(['A', 'B', 'Aaba', 'Baca', np.nan, 'CABA', 'cat'])
+    >>> s.str.count('a')
+    0    0.0
+    1    0.0
+    2    2.0
+    3    2.0
+    4    NaN
+    5    0.0
+    6    1.0
+    dtype: float64
+
+    Escape ``'$'`` to find the literal dollar sign.
+
+    >>> s = pd.Series(['$', 'B', 'Aab$', '$$ca', 'C$B$', 'cat'])
+    >>> s.str.count('\$')
+    0    1
+    1    0
+    2    1
+    3    2
+    4    2
+    5    0
+    dtype: int64
+
+    This is also available on Index
+
+    >>> pd.Index(['A', 'A', 'Aaba', 'cat']).str.count('a')
+    Int64Index([0, 0, 2, 1], dtype='int64')
     """
     regex = re.compile(pat, flags=flags)
     f = lambda x: len(regex.findall(x))