[GitHub] [arrow] danepitkin commented on a diff in pull request #37656: Add examples for MapArray.from_arrays

["danepitkin (via GitHub)" <gi...@apache.org>]

danepitkin commented on code in PR #37656:
URL: https://github.com/apache/arrow/pull/37656#discussion_r1321784680


##########
python/pyarrow/array.pxi:
##########
@@ -2363,6 +2363,77 @@ cdef class MapArray(ListArray):
         Returns
         -------
         map_array : MapArray
+
+        Examples
+        --------
+        First construct a rectangular model of the data. The total of 5 respondents
+        answered the question "How much did you like the movie x?". The value -1
+        means that the values is missing.

Review Comment:
   ```suggestion
           First, let's understand the structure of our dataset when viewed in a rectangular data model. 
           The total of 5 respondents answered the question "How much did you like the movie x?".
           The value -1 in the integer array means that the value is missing. The boolean array
           represents the null bitmask corresponding to the missing values in the integer array.
   ```



##########
python/pyarrow/array.pxi:
##########
@@ -2363,6 +2363,77 @@ cdef class MapArray(ListArray):
         Returns
         -------
         map_array : MapArray
+
+        Examples
+        --------
+        First construct a rectangular model of the data. The total of 5 respondents
+        answered the question "How much did you like the movie x?". The value -1
+        means that the values is missing.
+
+        >>> movies_rectangular = np.ma.masked_array([
+        >>>     [10, -1, -1],
+        >>>     [8, 4, 5],
+        >>>     [-1, 10, 3],
+        >>>     [-1, -1, -1],
+        >>>     [-1, -1, -1]
+        >>> ],
+        >>> [
+        >>>     [False, True, True],
+        >>>     [False, False, False],
+        >>>     [True, False, False],
+        >>>     [True, True, True],
+        >>>     [True, True, True],
+        >>> ])
+
+        To represent the same data with the MapArray and from_arrays, the data is
+        formed like this:
+
+        >>> offsets = [
+        >>>     0, #  -- row 1 start
+        >>>     1, #  -- row 2 start
+        >>>     4, #  -- row 3 start
+        >>>     6, #  -- row 4 start
+        >>>     6, #  -- row 5 start
+        >>>     6, #  -- row 5 end
+        >>> ]
+        >>> movies = [
+        >>>     "Dark Knight", #  ---------------------------------- row 1
+        >>>     "Dark Knight", "Meet the Parents", "Superman", #  -- row 2
+        >>>     "Meet the Parents", "Superman", #  ----------------- row 3
+        >>> ]
+        >>> likings = [
+        >>>     10, #  -------- row 1
+        >>>     8, 4, 9, #  --- row 2
+        >>>     10, 5 #  ------ row 3

Review Comment:
   ```suggestion
           >>>     8, 4, 5, #  --- row 2
           >>>     10, 3 #  ------ row 3
   ```



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