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Python – Extract Monodigit elements
• Last Updated : 11 Oct, 2020

Given List of numbers, extract all numbers with only similar digit.

Input : test_list = [463, 888, 123, ‘aaa’, 112, 111, ‘gfg’, 939, 4, ‘ccc’]
Output : [888, ‘aaa’, 111, 4, ‘ccc’]
Explanation : All elements having single unique digit or character.

Input : test_list = [463, “GFG”, 8838, 43, 991]
Output : []
Explanation : No element found to be having only single digit.

Method #1 : Using list comprehension + all()

In this, we iterate all the elements using list comprehension, all() is used to check equality of all digits with first digit.

## Python3

 `# Python3 code to demonstrate working of``# Extract Monodigit elements``# Using list comprehension + all()`` ` `# initializing list``test_list ``=` `[``463``, ``888``, ``123``, ``"aaa"``, ``112``, ``111``, ``"gfg"``, ``939``, ``4``, ``"ccc"``]`` ` `# printing original lists``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# all() checks for all similar digits``res ``=` `[sub ``for` `sub ``in` `test_list ``if` `all``(``    ``str``(ele) ``=``=` `str``(sub)[``0``] ``for` `ele ``in` `str``(sub))]`` ` `# printing result``print``(``"Extracted Numbers : "` `+` `str``(res))`

Output:

The original list is : [463, 888, 123, ‘aaa’, 112, 111, ‘gfg’, 939, 4, ‘ccc’]
Extracted Numbers : [888, ‘aaa’, 111, 4, ‘ccc’]

Method #2 : Using filter() + lambda + all()

In this, we perform task of filtering using lambda function, filter(), and all() is again used to check equality of all digits.

## Python3

 `# Python3 code to demonstrate working of``# Extract Monodigit elements``# Using filter() + lambda + all()`` ` `# initializing list``test_list ``=` `[``463``, ``888``, ``123``, ``"aaa"``, ``112``, ``111``, ``"gfg"``, ``939``, ``4``, ``"ccc"``]`` ` `# printing original lists``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# all() checks for all similar digits``# filter() used for filtering``res ``=` `list``(``filter``(``lambda` `sub: ``all``(``str``(ele) ``=``=` `str``(``    ``sub)[``0``] ``for` `ele ``in` `str``(sub)), test_list))`` ` `# printing result``print``(``"Extracted Numbers : "` `+` `str``(res))`

Output:

The original list is : [463, 888, 123, ‘aaa’, 112, 111, ‘gfg’, 939, 4, ‘ccc’]
Extracted Numbers : [888, ‘aaa’, 111, 4, ‘ccc’]

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