Select rows by partial string match in index

Question

Having a series like this:

ds = Series({'wikipedia':10,'wikimedia':22,'wikitravel':33,'google':40})

google        40
wikimedia     22
wikipedia     10
wikitravel    33
dtype: int64

I would like to select the rows where 'wiki' is a part of the index label (a partial string label).

For the moment I tried

ds[ds.index.map(lambda x: 'wiki' in x)]

wikimedia     22
wikipedia     10
wikitravel    33
Name: site, dtype: int64

and it does the job, but somehow the index cries for 'contains' just like what the columns have...

Any better way to do that?

Answer 1

A somewhat cheeky way could be to use loc:

In [11]: ds.loc['wiki': 'wikj']
Out[11]:
wikimedia     22
wikipedia     10
wikitravel    33
dtype: int64

This is essentially equivalent to ds[ds.index.map(lambda s: s.startswith('wiki'))].

To do contains, as @DSM suggests, it's probably nicer to write as:

ds[['wiki' in s for s in ds.index]]

Answer 2

An alternative (to Andy Hayden's answer) using filter, see here:

>>> ds.filter(like='wiki', axis=0)
wikimedia     22
wikipedia     10
wikitravel    33
dtype: int64

Answer 3

From the original question:

"...index cries for 'contains' just like what the columns have".

I'm not sure when this was added (this is an old question), but you can now use contains on index.str assuming your index is a string type:

>>> import pandas as pd
>>>
>>> ds = pd.Series({'wikipedia':10,'wikimedia':22,'wikitravel':33,'google':40})
>>> ds[ds.index.str.contains("wiki")]

wikipedia     10
wikimedia     22
wikitravel    33
dtype: int64