Pandas Multiindex - Select from List

Question

I have the following DataFrame with Index Date and ID

                  V1   V2
Date       ID
01.01.2010  1      x    y
01.01.2010  2      x    y
02.01.2010  1      x    y
        ......

I was able to select a date range with

df.loc[ slice(start, end) ]

But I need to filter data based on a list of ID's. For example

allowed = [1, 5]
df.loc[ allowed ]

How this is possible?

Nickil Maveli · Accepted Answer · 2017-03-25 07:27:12Z

2

Use index.isin to check for membership across Index axis. In the case of a multi-index, supply the position of the level or level name explicitly for which the check has to be performed.

df.loc[df.index.isin(allowed, level='ID')]    # level name is specified

(Or)

df.loc[df.index.isin(allowed, level=1)]       # level position is specified

edited Mar 25, 2017 at 7:27

answered Mar 25, 2017 at 7:14

Nickil Maveli

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MaxU - stand with Ukraine · Accepted Answer · 2017-03-25 08:44:16Z

1

You can also use .query() method:

In [62]: df
Out[62]:
              V1 V2
Date       ID
2010-01-01 1   x  y
           2   x  y
2010-02-01 1   x  y

In [63]: allowed = [1, 5]

In [64]: df.query("ID in @allowed")
Out[64]:
              V1 V2
Date       ID
2010-01-01 1   x  y
2010-02-01 1   x  y

answered Mar 25, 2017 at 8:44

MaxU - stand with Ukraine

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