ENH Add MultiIndex.from_product convenience function #6055

mwaskom · 2014-01-24T03:00:50Z

Following up on this StackOverflow post.

This is a convenience function for when you have a set of iterables and you want to make a MultiIndex with each unique paring of the values in those iterables.

~~I'm testing it against itertools.product since it uses the internal cartesian_product function; please let me know if there are additional tests that would make sense.~~

Testing against MultiIndex.from_tuples instead.

jreback · 2014-01-24T11:51:43Z

pandas/tests/test_index.py

+        result = MultiIndex.from_iterables([first, second], names=names)
+
+        product = list(itertools.product(first, second))
+        self.assertEquals(list(result), product)


use assert_array_equals here
also test that this equals to a constructed instance using MultiIndex.from_tuples (but construct if by writing out the tuples)
eg make it so it doesn't depend on iter tools or other routines)
that was if some ordering changes u are covered

add a release notes entry in improvements section

an example in v0.13.1

same example in the multi-index construction section in main docs (eg where Multiindex.from_tuples is introduced)

jorisvandenbossche · 2014-01-24T12:27:16Z

I have a remark about this. First, it's really usefull functionality! (it's indeed a common usecase)

But the name sounds confusing to me. Because it seems not that important that it are iterables, but that it's from a cross combination of two iterables (you can also use iterables in from_arrays/from_tuples). For me it's not obvious that if you have iterables that you would logically take a product of it.
But I admit I don't directly have that clear or short alternatives (from_combination, from_product, from_iter_product, from_cartesias_product, ..)

jreback · 2014-01-24T12:32:55Z

from_product 👍

jreback · 2014-01-24T12:33:30Z

@mwaskom FYI, use this PR number in release notes / v0.13.1 (as the reference issue)

mwaskom · 2014-01-25T18:13:52Z

OK, should be good

jreback · 2014-01-25T18:33:21Z

doc/source/v0.13.1.txt

+  shades = ['light', 'dark']
+  colors = ['red', 'green', 'blue']
+
+  index = pandas.MultiIndex.from_product([shades, colors],


dont't put the index = (if you assign to a variable then ipython wont' show it), and don't need the pandas everything is imported here

jreback · 2014-01-25T18:34:35Z

small changes

pls rebase and squash into 1 commit, see here: https://github.com/pydata/pandas/wiki/Using-Git

mwaskom · 2014-01-25T18:44:47Z

OK, sorry, git question.

I rebased and squashed, i.e. git log now shows

commit 493eb08fd59c4776b2a072b37646fef3aa09d661
Author: mwaskom <[email protected]>
Date:   Thu Jan 23 18:57:22 2014 -0800

    ENH Add MultiIndex.from_product convenience function

    FIX typo in from_iterables docstring

    ENH Rename from_iterables to from_product

    TST rework from_product test to compare against from_tuples

    DOC Add notes on from_product to release notes and indexing docs

    DOC clean from_product examples in docs

commit b537df5f9d4a783f8edad20ce53968c74ad56985
Merge: 039c57d d6667b1
Author: jreback <[email protected]>
Date:   Sat Jan 25 10:03:52 2014 -0800

    Merge pull request #6097 from jreback/hdf_fix

    TST: don't compare inferred index freq on some tests as it may not be preser

But now I cannot push to this branch due to

[pandas]{multiindex_from_iterables}$ git push origin multiindex_from_iterables
Username for 'https://github.com': mwaskom
Password for 'https://[email protected]':
To https://github.com/mwaskom/pandas.git
 ! [rejected]        multiindex_from_iterables -> multiindex_from_iterables (non-fast-forward)
error: failed to push some refs to 'https://github.com/mwaskom/pandas.git'
To prevent you from losing history, non-fast-forward updates were rejected
Merge the remote changes (e.g. 'git pull') before pushing again.  See the
'Note about fast-forwards' section of 'git push --help' for details.

What's the right thing to do?

jreback · 2014-01-25T19:30:59Z

try this

git fetch upstream/master
git rebase -i upstream/master

remove all but your commit

then

git push origin thisbranchname -f

(the -f force pushes)

mwaskom · 2014-01-25T19:33:24Z

OK that's what I thought but wasn't sure.

jreback · 2014-01-25T19:55:38Z

@mwaskom excellent git-fu

any other comments

@jorisvandenbossche
@jtratner

jorisvandenbossche · 2014-01-25T21:38:02Z

doc/source/v0.13.1.txt

+  shades = ['light', 'dark']
+  colors = ['red', 'green', 'blue']
+
+  MultiIndex.from_product([shades, colors], names=['shade', 'color'])


These three code lines need an indentation. Also, I think they are meant as code that should be ran? Then the code-block -> ipython

FIX typo in from_iterables docstring ENH Rename from_iterables to from_product TST rework from_product test to compare against from_tuples DOC Add notes on from_product to release notes and indexing docs DOC clean from_product examples in docs DOC Further clarify from_product docs

mwaskom · 2014-01-25T23:00:27Z

I think that addresses everything.

jreback · 2014-01-25T23:17:34Z

@jorisvandenbossche ok by me...go ahead and merge if you are ok

jorisvandenbossche · 2014-01-25T23:21:49Z

Yes, certainly fine. Thanks a lot @mwaskom !

ENH Add MultiIndex.from_product convenience function

ghost · 2014-01-27T19:59:37Z

I just reached for this and it was there. 👍

jreback reviewed Jan 24, 2014
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jreback reviewed Jan 25, 2014
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jorisvandenbossche reviewed Jan 25, 2014
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jorisvandenbossche added a commit that referenced this pull request Jan 25, 2014

Merge pull request #6055 from mwaskom/multiindex_from_iterables

63ce94d

ENH Add MultiIndex.from_product convenience function

jorisvandenbossche merged commit 63ce94d into pandas-dev:master Jan 25, 2014

jreback mentioned this pull request Feb 8, 2014

MultiIndex init function #4824

Closed

mwaskom deleted the multiindex_from_iterables branch September 4, 2021 21:18

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ENH Add MultiIndex.from_product convenience function #6055

ENH Add MultiIndex.from_product convenience function #6055

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ENH Add MultiIndex.from_product convenience function #6055

ENH Add MultiIndex.from_product convenience function #6055

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