Create an pandas column if a string from a list matches from another column

Question

I have a pandas dataframe which is similar to the follow but a lot bigger and complicated.

import pandas as pd
d = {'weight': [70, 10, 65, 1], 'String1': ['Labrador is a dog',
'Abyssinian is a cat',
'German Shepard is a dog',
'pigeon is a bird']}
df = pd.DataFrame(data=d)
df

Output

	Weight	String
0	70	Labrador is a dog
1	10	Abyssinian is a cat
2	65	German Shepard is a dog
3	1	pigeon is a bird

I want to create a new column, 'animal' based on column 'string1'

search_list = ['dog','cat']

if in 'search_list', then populate the value from the search list, else populate 'other'

	Weight	String	animal
0	70	Labrador is a dog	dog
1	10	Abyssinian is a cat	cat
2	65	German Shepard is a dog	dog
3	1	pigeon is a bird	other

Please suggest how to do this. Thank you.

Andrew Eckart · Accepted Answer · 2021-08-21 01:55:15Z

2

Here is one way to do it which leverages the built-in next function and its default argument:

In [7]: df["animal"] = df["String1"].map(lambda s: next((animal for animal in search_list if animal in s), "other"))
   ...:

In [8]: df
Out[8]:
   weight                  String1 animal
0      70        Labrador is a dog    dog
1      10      Abyssinian is a cat    cat
2      65  German Shepard is a dog    dog
3       1         pigeon is a bird  other

Note that if String1 is something like "I have a dog and a cat", then this will return whichever animal appears first in the search_list.

answered Aug 21, 2021 at 1:55

Andrew Eckart

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Comments

Anurag Dabas · Accepted Answer · 2021-08-21 02:07:15Z

2

You can use str.extract()+fillna():

df['animal']=df['String1'].str.extract(pat='(dog|cat)',expand=False).fillna('other')

OR

If you have a list of long length then:

pat='('+'|'.join(search_list)+')'
df['animal']=df['String1'].str.extract(pat=pat,expand=False).fillna('other')

output of df:

    weight  String1                     animal
0   70      Labrador is a dog           dog
1   10      Abyssinian is a cat         cat
2   65      German Shepard is a dog     dog
3   1       pigeon is a bird            other

answered Aug 21, 2021 at 2:07

Anurag Dabas

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Comments

lionking-123 · Accepted Answer · 2021-08-21 02:13:35Z

0

df["animal"] = "other" # initial set
df.loc[df["String"].str.contains("dog", case=True), "animal"] = "dog"
df.loc[df["String"].str.contains("cat", case=True), "animal"] = "cat"

Hope to be helpful for you. Thanks.

answered Aug 21, 2021 at 2:13

lionking-123

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