re.MatchObject.groupdict() function in Python - Regex

Last Updated : 29 Aug, 2020

This method returns a dictionary with the groupname as keys and the matched string as the value for that key.

Syntax: re.MatchObject.groupdict()

Return: A dictionary with groupnames as the keys and matched string as the value for the key.

AttributeError: If a matching pattern is not found then it raise AttributeError.

Consider the below example:

Example 1:

A program to create and print a detailed dictionary which will consist of username, website, and the domain.

Python3

import re

"""We create a re.MatchObject and store it in 
   match_object variable
   the '()' parenthesis are used to define a 
   specific group"""

match_object = re.match(
    r'(?P<Username>\w+)@(?P<Website>\w+)\.(?P<Domain>\w+)', '[email protected]')

""" w in above pattern stands for alphabetical character
    + is used to match a consecutive set of characters 
    satisfying a given condition
    so w+ will match a consecutive set of alphabetical characters
    The ?P<Username> in '()'(the round brackets) is 
    used to capture subgroups of strings satisfying 
    the above condition and the groupname is 
    specified in the ''(angle brackets)in this 
    case its Username."""

# generating a dictionary from the given emailID
details = match_object.groupdict()

# printing the dictionary
print(details)

Output:

{'Username': 'jon', 'Website': 'geekforgeeks', 'Domain': 'org'}

It's time to understand the above program. We use a re.match() method to find a match in the given string('[email protected]') the 'w' indicates that we are searching for an alphabetical character and the '+' indicates that we are searching for continuous alphabetical characters in the given string. Note the use of '()' the parenthesis is used to define different subgroups, in the above example, we have three subgroups in the match pattern. The '?P' syntax is used to define the groupname for capturing the specific groups. The result we get is a re.MatchObject which is stored in match_object.

To know more about regex patterns visit this post. Python regex

Example 2: If a match object is not found then it raises AttributeError.

Python3

import re

"""We create a re.MatchObject and store it in 
   match_object variable
   the '()' parenthesis are used to define a 
   specific group"""

match_object = re.match(
    r'(?P<Username>\w+)@(?P<Website>\w+)\.(?P<Domain>\w+)', '1234567890')

""" w in above pattern stands for alphabetical character
    + is used to match a consecutive set of characters 
    satisfying a given condition
    so w+ will match a consecutive set of alphabetical characters
    The ?P<Username> in '()'(the round brackets) is 
    used to capture subgroups of strings satisfying 
    the above condition and the groupname is 
    specified in the ''(angle brackets)in this 
    case its Username."""

# Following line will raise AttributeError exception
print(match_object.groupdict())

Output:

Traceback (most recent call last):
  File "/home/fae2ec2e63d04a63d590c2e93802a002.py", line 21, in 
    print(match_object.groupdict())
AttributeError: 'NoneType' object has no attribute 'groupdict'