How to filter a pandas column by list of strings?

Question

The standard code for filtering through pandas would be something like:

output = df['Column'].str.contains('string')
strings = ['string 1', 'string 2', 'string 3']

Instead of 'string' though, I want to filter such that it goes through a collection of strings in list, "strings". So I tried something such as

output = df['Column'].str.contains('*strings')

This is the closest solution I could find, but did not work How to filter pandas DataFrame with a list of strings

Edit: I should note that I'm aware of the | or operator. However, I'm wondering how to tackle all cases in the instance list strings is changing and I'm looping through varying lists of changing lengths as the end goal.

do you want it to contain any or all of the strings in strings? — wpercy
– wpercy, Commented Apr 1, 2019 at 16:47
Any please, but would be nice to know for "all" anyways if you don't mind providing both — hiimarksman
– hiimarksman, Commented Apr 1, 2019 at 16:49
Try regstr = '|'.join(strings) and df['Column'].str.contains(regstr) — Scott Boston
– Scott Boston, Commented Apr 1, 2019 at 16:58

Victor Hugo Borges · Accepted Answer · 2019-04-01 16:59:50Z

8

You can create a regex string and search using this string.

Like this: df['Column'].str.contains('|'.join(strings),regex=True)

answered Apr 1, 2019 at 16:59

Victor Hugo Borges

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2 Comments

hiimarksman Over a year ago

This seemed to work. Thanks! I also just found df['Column'].isin(strings). The results seems to be identical, but is there any fundamental difference with the code you provided?

Victor Hugo Borges Over a year ago

The isin will look for exact matches inside the list. The contains will search for a text in which constains the string you passed in the list, using regex to find it. For example: pd.Series(['string 1 foo']).isin(strings) would return False. pd.Series(['string 1 foo']).str.contains('|'.join(strings),regex=True) would return True

Mutaz-MSFT · Accepted Answer · 2019-09-21 07:02:23Z

6

you probably should look into using isin() function (pandas.Series.isin) .

check the code below:

    df = pd.DataFrame({'Column':['string 1', 'string 1', 'string 2', 'string 2', 'string 3', 'string 4', 'string 5']})
    strings = ['string 1', 'string 2', 'string 3']
    output = df.Column.isin(strings)

    df[output]

output:

        Column
    0   string 1
    1   string 1
    2   string 2
    3   string 2
    4   string 3

answered Sep 21, 2019 at 7:02

Mutaz-MSFT

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2 Comments

bobo32 Over a year ago

AttributeError: 'DataFrame' object has no attribute 'Column'

Mutaz-MSFT Over a year ago

'Column' is the name of a column in the dataframe. do a print(df) to see its structure and data. @bobo32

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