Python | Pandas Series.str.extractall()

Series.str can be used to access the values of the series as strings and apply several methods to it. Pandas Series.str.extractall() function is used to extract capture groups in the regex pat as columns in a DataFrame. For each subject string in the Series, extract groups from all matches of regular expression pat. When each subject string in the Series has exactly one match, extractall(pat).xs(0, level=’match’) is the same as extract(pat).

Syntax: Series.str.extractall(pat, flags=0)

Parameter :
pat : Regular expression pattern with capturing groups.
flags : A re module flag, for example re.IGNORECASE.

Returns : DataFrame

Example #1: Use Series.str.extractall() function to extract all groups from the string in the underlying data of the given series object.

# importing pandas as pd
import pandas as pd

# importing re for regular expressions
import re

# Creating the Series
sr = pd.Series(['New_York', 'Lisbon', 'Tokyo', 'Paris', 'Munich'])

# Creating the index
idx = ['City 1', 'City 2', 'City 3', 'City 4', 'City 5']

# set the index
sr.index = idx

# Print the series
print(sr)

Output :

Now we will use Series.str.extractall() function to extract all groups from the strings in the given series object.

# extract all groups having a vowel followed by
# any character
result = sr.str.extractall(pat = '([aeiou].)')

# print the result
print(result)

Output :

As we can see in the output, the Series.str.extractall() function has returned a dataframe containing a column of all the extracted group.

Example #2 : Use Series.str.extractall() function to extract all groups from the string in the underlying data of the given series object.

# importing pandas as pd
import pandas as pd

# importing re for regular expressions
import re

# Creating the Series
sr = pd.Series(['Mike', 'Alessa', 'Nick', 'Kim', 'Britney'])

# Creating the index
idx = ['Name 1', 'Name 2', 'Name 3', 'Name 4', 'Name 5']

# set the index
sr.index = idx

# Print the series
print(sr)

Output :

Now we will use Series.str.extractall() function to extract all groups from the strings in the given series object.

# extract all groups having any capital letter
# followed by 'i' and any other character
result = sr.str.extractall(pat = '([A-Z]i.)')

# print the result
print(result)

Output :

As we can see in the output, the Series.str.extractall() function has returned a dataframe containing a column of all the extracted group.