Pandas Series: str.findall() function

Series-str.findall() function

The str.findall() function is used to Find all occurrences of pattern or regular expression in the Series/Index.

Equivalent to applying re.findall() to all the elements in the Series/Index.

Syntax:

Series.str.findall(self, pat, flags=0, **kwargs)

Parameters:

Returns: Series/Index of lists of strings
All non-overlapping matches of pattern or regular expression in each string of this Series/Index.

Example - The search for the pattern ‘Deer’ returns one match:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(['Tiger', 'Deer', 'Zoo'])
s.str.findall('Deer')

Output:

0        []
1    [Deer]
2        []
dtype: object

Example - On the other hand, the search for the pattern ‘DEER’ doesn’t return any match:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(['Tiger', 'Deer', 'Zoo'])
s.str.findall('DEER')

Output:

0    []
1    []
2    []
dtype: object

Example - Flags can be added to the pattern or regular expression. For instance, to find the pattern ‘DEER’ ignoring the case:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(['Tiger', 'Deer', 'Zoo'])
import re
s.str.findall('DEER', flags=re.IGNORECASE)

Output:

0        []
1    [Deer]
2        []
dtype: object

Example - When the pattern matches more than one string in the Series, all matches are returned:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(['Tiger', 'Deer', 'Zoo'])
s.str.findall('er')

Output:

0    [er]
1    [er]
2      []
dtype: object

Example - Regular expressions are supported too. For instance, the search for all the strings ending with the word ‘er’ is shown next:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(['Tiger', 'Deer', 'Zoo'])
s.str.findall('er$')

Output:

0    [er]
1    [er]
2      []
dtype: object

Example - If the pattern is found more than once in the same string, then a list of multiple strings is returned:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(['Tiger', 'Deer', 'Zoo'])
s.str.findall('o')

Output:

0        []
1        []
2    [o, o]
dtype: object

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