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Merged
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Jan 4, 2019
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DOC: update str.cat example #23723

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DOC: update str.cat example
h-vetinari Nov 15, 2018
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Merge remote-tracking branch 'upstream/master' into str_cat_docs
h-vetinari Nov 18, 2018
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Review (jreback & WillAyd)
h-vetinari Nov 18, 2018
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Review (WillAyd & jreback)
h-vetinari Nov 19, 2018
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Merge remote-tracking branch 'upstream/master' into str_cat_docs
h-vetinari Nov 20, 2018
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Merge and remove Index from example (review jreback)
h-vetinari Jan 2, 2019
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Merge remote-tracking branch 'upstream/master' into str_cat_docs
h-vetinari Jan 3, 2019
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Review (WillAyd)
h-vetinari Jan 3, 2019
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Merge remote-tracking branch 'upstream/master' into str_cat_docs
h-vetinari Jan 3, 2019
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Review (jreback)
h-vetinari Jan 3, 2019
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Merge remote-tracking branch 'upstream/master' into str_cat_docs
h-vetinari Jan 4, 2019
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12 changes: 6 additions & 6 deletions doc/source/text.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -303,23 +303,23 @@ The same alignment can be used when ``others`` is a ``DataFrame``:
Concatenating a Series and many objects into a Series
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

All one-dimensional list-likes can be combined in a list-like container (including iterators, ``dict``-views, etc.):
Several items (specifically: ``Series``, ``Index``, ``PandasArray`` and ``np.ndarray``) can be combined in a list-like container (including iterators, ``dict``-views, etc.).

.. ipython:: python

s
u
s.str.cat([u.array,
u.index.astype(str).array], na_rep='-')
s.str.cat([u, u.array, u.to_numpy()], join='left')

All elements must match in length to the calling ``Series`` (or ``Index``), except those having an index if ``join`` is not None:
All elements without an index (e.g. ``PandasArray`` and ``np.ndarray``) within the passed list-like must match in length to the calling ``Series`` (or ``Index``),
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Might have missed this but what's the reason for bringing up PandasArray? Not really something the end user would be using directly (at least in current form)

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PandasArray is very user-facing:

>>> s = pd.Series(['a', 'b' ,'c', 'd'])
>>> s.array
<PandasArray>
['a', 'b', 'c', 'd']
Length: 4, dtype: object

and the current example was recently changed to use .array instead of .values. I think this should be documented clearly.

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OK thanks. I have been somewhat on the sidelines for that conversation so I'll defer to @jreback specifically on this piece

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You don't need to mention PandasArray here, its not very interesting, nor relevant. Just say array-likes. and remove u.array, the u.to_numpy() is the corrent idiom here.

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@jreback
There is a big difference between u.array and u.to_numpy():

>>> s = pd.Series(['a', 'b', 'c', 'd'])
>>> s.array
<PandasArray>
['a', 'b', 'c', 'd']
Length: 4, dtype: object
>>> s.to_numpy()
array(['a', 'b', 'c', 'd'], dtype=object)

I'm guessing .array will eventually replace .values-usage (e.g. to get rid of the index for .str.cat), since it is by design better suited for pandas-internal dtypes, and so the distinction above is not just an irrelevant detail IMO.

I want to show here the explicitly allowed item types to pass into a list-like, which have to pass:

nxt = others.pop(0)
[...]
if not (isinstance(nxt, (Series, Index))
        or (isinstance(nxt, np.ndarray) and nxt.ndim == 1)):
    raise ValueError(...)  # currently just a DeprecationWarning

Long story short, I want to show a list-like containing an np.ndarray, a PandasArray (to reiterate, this example was already changed by @TomAugspurger to use .array instead of .values in #23623), and a Series. (Including Index would be nice-to-have, but too complicated absent #22225).

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@h-vetinari .to_numpy() replaces .values; .array is user-accessible, but generally is not visible to by the user. its not necessary here and is just noise.

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@h-vetinari h-vetinari Jan 3, 2019 •
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@jreback

.to_numpy() replaces .values;

As I did in the last few commits...

.array is user-accessible, but generally is not visible to by the user. its not necessary here and is just noise.

Will remove, but pinging @TomAugspurger since he added the current u.array in this example in #23623 (although likely "just" for replacing u.values?).

but ``Series`` and ``Index`` may have arbitrary length (as long as alignment is not disabled with ``join=None``):

.. ipython:: python

v
s.str.cat([u, v], join='outer', na_rep='-')
s.str.cat([v, u, u.to_numpy()], join='outer', na_rep='-')

If using ``join='right'`` on a list of ``others`` that contains different indexes,
If using ``join='right'`` on a list-like of ``others`` that contains different indexes,
the union of these indexes will be used as the basis for the final concatenation:

.. ipython:: python
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