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DOC: Improving docstring of take method #16948

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DOC: Address reviewer comments
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gfyoung committed Aug 21, 2017
commit 0a077750951467c273368f113b26c7411e131b80
60 changes: 40 additions & 20 deletions pandas/core/generic.py
Original file line number Diff line number Diff line change
Expand Up @@ -2063,57 +2063,77 @@ def __delitem__(self, key):

def take(self, indices, axis=0, convert=True, is_copy=True, **kwargs):
"""
Return an object formed from the elements in the given indices along an
axis
Return the elements in the given *positional* indices along an axis.

This means that we are not indexing according to actual values in
the index attribute of the object. We are indexing according to the
actual position of the element in the object.

Parameters
----------
indices : list / array of ints
indices : array-like
An array of ints indicating which positions to take.
axis : int, default 0
convert : translate neg to pos indices (default)
is_copy : mark the returned frame as a copy
The axis on which to select elements. "0" means that we are
selecting rows, "1" means that we are selecting columns, etc.
convert : bool, default True
Whether to convert negative indices to positive ones, just as with
indexing into Python lists. For example, if `-1` was passed in,
this index would be converted ``n - 1``.
is_copy : bool, default True
Whether to return a copy of the original object or not.

Examples
--------
>>> import numpy as np
>>> import pandas as pd
>>> df = pd.DataFrame([('falcon', 'bird', 389.0),
('parrot', 'bird', 24.0),
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give this an index (like [0, 3, 2, 1]) or something to emphasize that these are positional operations

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Done.

('lion', 'mammal', 80.5),
('monkey', 'mammal', np.nan)],
columns=('name', 'class', 'max_speed'))
columns=('name', 'class', 'max_speed'),
index=[0, 2, 3, 1])
>>> df
name class max_speed
0 falcon bird 389.0
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add a comment that these are positional selections (where you think it is needed)

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Done.

1 parrot bird 24.0
2 lion mammal 80.5
3 monkey mammal NaN
2 parrot bird 24.0
3 lion mammal 80.5
1 monkey mammal NaN

Take elements at positions 0 and 3 along the axis 0 (default).

Take elements at indices 0 and 3 along the axis 0 (default)
Note how the actual indices selected (0 and 1) do not correspond to
our selected indices 0 and 3. That's because we are selecting the 0th
and 3rd rows, not rows whose indices equal 0 and 3.

>>> df.take([0, 3])
0 falcon bird 389.0
3 monkey mammal NaN
1 monkey mammal NaN

Take elements at indices 1 and 2 along the axis 1
Take elements at indices 1 and 2 along the axis 1 (column selection).

>>> df.take([1, 2], axis=1)
class max_speed
0 bird 389.0
1 bird 24.0
2 mammal 80.5
3 mammal NaN
2 bird 24.0
3 mammal 80.5
1 mammal NaN

Also, we may take elements using negative integers for pos indices
We may take elements using negative integers for positive indices,
starting from the end of the object, just like with Python lists.

>>> df.take([-1, -2])
name class max_speed
3 monkey mammal NaN
2 lion mammal 80.5
1 monkey mammal NaN
3 lion mammal 80.5

Returns
-------
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add a See Also, showing ndarray.take

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Done.

taken : type of caller
An array-like containing the elements taken from the object.

See Also
--------
numpy.ndarray.take
numpy.take
"""
nv.validate_take(tuple(), kwargs)
self._consolidate_inplace()
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