# Python | Minimum K records of Nth index in tuple list

Sometimes, while working with data, we can have a problem in which we need to get the minimum of elements filtered by the Nth element of record. This has a very important utility in web development domain. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using `filter() + lambda + set()` + list comprehension
The combination of above functions can be used to perform this particular function. In this, we first filter the min K elements from Nth index and then apply this values to the list and return the result.

 `# Python3 code to demonstrate working of ` `# Minimum K records of Nth index in tuple list ` `# Using filter() + lambda + set() + list comprehension ` ` `  `# initialize list  ` `test_list ``=` `[(``'gfg'``, ``4``, ``'good'``), (``'gfg'``, ``2``, ``'better'``),  ` `              ``(``'gfg'``, ``1``, ``'best'``), (``'gfg'``, ``3``, ``'geeks'``)] ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initialize N  ` `N ``=` `1` ` `  `# initialize K  ` `K ``=` `2` ` `  `# Minimum K records of Nth index in tuple list ` `# Using filter() + lambda + set() + list comprehension ` `temp ``=` `set``(``list``({sub[N] ``for` `sub ``in` `test_list})[ :K]) ` `res ``=` `list``(``filter``(``lambda` `sub: sub[N] ``in` `temp, test_list)) ` ` `  `# printing result ` `print``(``"Min K elements of Nth index are : "` `+` `str``(res)) `

Output :

The original list is : [(‘gfg’, 4, ‘good’), (‘gfg’, 2, ‘better’), (‘gfg’, 1, ‘best’), (‘gfg’, 3, ‘geeks’)]
Min K elements of Nth index are : [(‘gfg’, 2, ‘better’), (‘gfg’, 1, ‘best’)]

Method #2 : Using` groupby() + sorted()` + loop
This task can also be performed using above functionalities. In this, we first group the min K elements together and then limit by K while constructing the result list.

 `# Python3 code to demonstrate working of ` `# Minimum K records of Nth index in tuple list ` `# Using groupby() + sorted() + loop ` `import` `itertools ` ` `  `# initialize list  ` `test_list ``=` `[(``'gfg'``, ``4``, ``'good'``), (``'gfg'``, ``2``, ``'better'``), ` `              ``(``'gfg'``, ``1``, ``'best'``), (``'gfg'``, ``3``, ``'geeks'``)] ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initialize N  ` `N ``=` `1` ` `  `# initialize K  ` `K ``=` `2` ` `  `# Minimum K records of Nth index in tuple list ` `# Using groupby() + sorted() + loop ` `res ``=` `[] ` `temp ``=` `itertools.groupby(``sorted``(test_list, key ``=` `lambda` `sub : sub[N]),  ` `                                            ``key ``=` `lambda` `sub : sub[N]) ` ` `  `for` `i ``in` `range``(K): ` `    ``res.extend(``list``(``next``(temp)[N])) ` ` `  `# printing result ` `print``(``"Min K elements of Nth index are : "` `+` `str``(res)) `

Output :

The original list is : [(‘gfg’, 4, ‘good’), (‘gfg’, 2, ‘better’), (‘gfg’, 1, ‘best’), (‘gfg’, 3, ‘geeks’)]
Min K elements of Nth index are : [(‘gfg’, 2, ‘better’), (‘gfg’, 1, ‘best’)]

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