Merge remote-tracking branch 'upstream/master' into DOC-DocTests-core-groupby

Author: MomIsBestFriend

ci/code_checks.sh

@@ -310,7 +310,11 @@ if [[ -z "$CHECK" || "$CHECK" == "doctests" ]]; then
     pytest -q --doctest-modules pandas/core/indexes/
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 
-    MSG='Doctests reshaping functions' ; echo $MSG
+    MSG='Doctests ops' ; echo $MSG
+    pytest -q --doctest-modules pandas/core/ops/
+    RET=$(($RET + $?)) ; echo $MSG "DONE"
+
+    MSG='Doctests reshape' ; echo $MSG
     pytest -q --doctest-modules pandas/core/reshape/
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 

pandas/core/generic.py

@@ -8062,15 +8062,21 @@ def first(self: FrameOrSeries, offset) -> FrameOrSeries:
 
     def last(self: FrameOrSeries, offset) -> FrameOrSeries:
         """
-        Method to subset final periods of time series data based on a date offset.
+        Select final periods of time series data based on a date offset.
+
+        When having a DataFrame with dates as index, this function can
+        select the last few rows based on a date offset.
 
         Parameters
         ----------
         offset : str, DateOffset, dateutil.relativedelta
+            The offset length of the data that will be selected. For instance,
+            '3D' will display all the rows having their index within the last 3 days.
 
         Returns
         -------
-        subset : same type as caller
+        Series or DataFrame
+            A subset of the caller.
 
         Raises
         ------

pandas/core/ops/missing.py

@@ -72,7 +72,7 @@ def fill_zeros(result, x, y):
 
 def mask_zero_div_zero(x, y, result):
     """
-    Set results of 0 / 0 or 0 // 0 to np.nan, regardless of the dtypes
+    Set results of  0 // 0 to np.nan, regardless of the dtypes
     of the numerator or the denominator.
 
     Parameters
@@ -83,13 +83,16 @@ def mask_zero_div_zero(x, y, result):
 
     Returns
     -------
-    filled_result : ndarray
+    ndarray
+        The filled result.
 
     Examples
     --------
     >>> x = np.array([1, 0, -1], dtype=np.int64)
+    >>> x
+    array([ 1,  0, -1])
     >>> y = 0       # int 0; numpy behavior is different with float
-    >>> result = x / y
+    >>> result = x // y
     >>> result      # raw numpy result does not fill division by zero
     array([0, 0, 0])
     >>> mask_zero_div_zero(x, y, result)