Pandas converting String object to lower case and checking for string

Question

I have the below code

import pandas as pd
private = pd.read_excel("file.xlsx","Pri")
public = pd.read_excel("file.xlsx","Pub")
private["ISH"] = private.HolidayName.str.lower().contains("holiday|recess")
public["ISH"] = public.HolidayName.str.lower().contains("holiday|recess")

I get the following error:

AttributeError: 'Series' object has no attribute 'contains'

Is there anyway to convert the 'HolidayName' column to lower case and then check the regular expression ("Holiday|Recess")using .contains in one step?

If you convert the terms to lowercase, they'll never contain uppercase letters like H or R.. — DSM
– DSM, Commented Apr 7, 2014 at 10:08
Thank you for pointing that out. It was an oversight when I was typing out my example. Have fixed it. — user1452759
– user1452759, Commented Apr 7, 2014 at 10:09

unutbu · Accepted Answer · 2014-04-07 10:07:54Z

99

private["ISH"] = private.HolidayName.str.contains("(?i)holiday|recess")

The (?i) in the regex pattern tells the re module to ignore case.

The reason why you were getting an error is because the Series object does not have the contains method; instead the Series.str attribute has the contains method. So you could avoid the error with:

private["ISH"] = private.HolidayName.str.lower().str.contains("holiday|recess")

answered Apr 7, 2014 at 10:07

unutbu

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4 Comments

william_grisaitis Over a year ago

nice! is this in the docs somewhere? is this a pandas-specific thing, or something else? guessing something else.

unutbu Over a year ago

@grisaitis: The vectorized string methods are documented here. The use of (?i) to do case-insensitive pattern matching is part of the Python re module's regular expression syntax. (Search for the string (?iLmsux)).

BobHy Over a year ago

Sad that the best answer to this problem involves deep knowlege of RE. N00bs (such as myself) are looking to chain the str operations.

ggupta Over a year ago

just to add, if you want an exact match, then df[(private['HolidayName'].str.lower() == "holiday")] should work

Bonqus · Accepted Answer · 2019-04-14 16:09:20Z

24

I'm a bit late to the party, but you could use the keyarg case : bool, default True, If True, case sensitive.

private["ISH"] = private.HolidayName.str.contains("holiday|recess", case=False)
public["ISH"] = public.HolidayName.str.contains("holiday|recess", case=False)

answered Apr 14, 2019 at 16:09

Bonqus

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1 Comment

Derek Eden Over a year ago

FYI - checked all 3 methods (chaining str, using regex, using case=False).....turns out regex is the fastest, case=False method is about 1.25 times longer, chaining str is about 1.06 times longer

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