# Group List of Dictionary Data by Particular Key in Python

• Last Updated : 19 Aug, 2022

Group List of Dictionary Data by Particular Key in Python can be done using itertools.groupby() method.

## Itertools.groupby()

This method calculates the keys for each element present in iterable. It returns key and iterable of grouped items.

Syntax: itertools.groupby(iterable, key_func)

Parameters:

• iterable: Iterable can be of any kind (list, tuple, dictionary).
• key_func: A function that calculates keys for each element present in iterable.

Return type: It returns consecutive keys and groups from the iterable. If the key function is not specified or is None, key defaults to an identity function and returns the element unchanged.

Let’s see the examples: Example 1: Suppose we have list of dictionary of employee and company.

```INFO = [
{'employee': 'XYZ_1', 'company': 'ABC_1'},
{'employee': 'XYZ_2', 'company': 'ABC_2'},
{'employee': 'XYZ_3', 'company': 'ABC_3'},
{'employee': 'XYZ_4', 'company': 'ABC_3'},
{'employee': 'XYZ_5', 'company': 'ABC_2'},
{'employee': 'XYZ_6', 'company': 'ABC_3'},
{'employee': 'XYZ_7', 'company': 'ABC_1'},
{'employee': 'XYZ_8', 'company': 'ABC_2'},
{'employee': 'XYZ_9', 'company': 'ABC_1'}
]```

Now we need to display all the data group by the ‘company’ key name.

Code:

## Python3

 `# import a groupby() method` `# from itertools module` `from` `itertools ``import` `groupby`   `# dictionary` `INFO ``=` `[` `    ``{``'employee'``: ``'XYZ_1'``, ``'company'``: ``'ABC_1'``},` `    ``{``'employee'``: ``'XYZ_2'``, ``'company'``: ``'ABC_2'``},` `    ``{``'employee'``: ``'XYZ_3'``, ``'company'``: ``'ABC_3'``},` `    ``{``'employee'``: ``'XYZ_4'``, ``'company'``: ``'ABC_3'``},` `    ``{``'employee'``: ``'XYZ_5'``, ``'company'``: ``'ABC_2'``},` `    ``{``'employee'``: ``'XYZ_6'``, ``'company'``: ``'ABC_3'``},` `    ``{``'employee'``: ``'XYZ_7'``, ``'company'``: ``'ABC_1'``},` `    ``{``'employee'``: ``'XYZ_8'``, ``'company'``: ``'ABC_2'``},` `    ``{``'employee'``: ``'XYZ_9'``, ``'company'``: ``'ABC_1'``}` `]`     `# define a function for key` `def` `key_func(k):` `    ``return` `k[``'company'``]`   `# sort INFO data by 'company' key.` `INFO ``=` `sorted``(INFO, key``=``key_func)`   `for` `key, value ``in` `groupby(INFO, key_func):` `    ``print``(key)` `    ``print``(``list``(value))`

Output:

ABC_1 [{’employee’: ‘XYZ_1’, ‘company’: ‘ABC_1′}, {’employee’: ‘XYZ_7’, ‘company’: ‘ABC_1′}, {’employee’: ‘XYZ_9’, ‘company’: ‘ABC_1′}] ABC_2 [{’employee’: ‘XYZ_2’, ‘company’: ‘ABC_2′}, {’employee’: ‘XYZ_5’, ‘company’: ‘ABC_2′}, {’employee’: ‘XYZ_8’, ‘company’: ‘ABC_2′}] ABC_3 [{’employee’: ‘XYZ_3’, ‘company’: ‘ABC_3′}, {’employee’: ‘XYZ_4’, ‘company’: ‘ABC_3′}, {’employee’: ‘XYZ_6’, ‘company’: ‘ABC_3’}]

Example 2: Suppose we have list of dictionary of student grades and marks.

```students = [
]```

Now we need to display all the data group by the ‘grade’ key.

Code:

## Python3

 `# import required methods` `from` `itertools ``import` `groupby` `from` `operator ``import` `itemgetter`   `# dictionary` `students ``=` `[` `    ``{``'mark'``: ``'65'``, ``'grade'``: ``'C'``},` `    ``{``'mark'``: ``'86'``, ``'grade'``: ``'A'``},` `    ``{``'mark'``: ``'73'``, ``'grade'``: ``'B'``},` `    ``{``'mark'``: ``'49'``, ``'grade'``: ``'D'``},` `    ``{``'mark'``: ``'91'``, ``'grade'``: ``'A'``},` `    ``{``'mark'``: ``'79'``, ``'grade'``: ``'B'``}` `]`   `# Sort students data by grade key.` `students ``=` `sorted``(students, ` `                  ``key ``=` `itemgetter(``'grade'``))`   `# Display data grouped by grade` `for` `key, value ``in` `groupby(students,` `                          ``key ``=` `itemgetter(``'grade'``)):` `    ``print``(key)` `    ``for` `k ``in` `value:` `        ``print``(k)`

Output:

```A