# Python program to convert a list to a set based on a common element

PythonServer Side ProgrammingProgramming

When it is required to convert a list to a set based on a specific common element, a method can be defined that iterates through the set using ‘enumerate’ and places a specific condition on the elements. The ‘union’ method and the ‘map’ methods are used.

## Example

Below is a demonstration of the same

def common_elem_set(my_set):
for index, val in enumerate(my_set):
for j, k in enumerate(my_set[index + 1:], index + 1):

if val & k:
my_set[index] = val.union(my_set.pop(j))
return common_elem_set(my_set)
return my_set

my_list = [[18, 14, 12, 19], [9, 6, 2, 1], [54, 32, 21, 17], [18, 11, 13, 12]]

print("The list is :")
print(my_list)

my_set = list(map(set, my_list))

my_result = common_elem_set(my_set)

print("The result is :")
print(my_result)

## Output

The list is :
[[18, 14, 12, 19], [9, 6, 2, 1], [54, 32, 21, 17], [18, 11, 13, 12]]
The result is :
[{11, 12, 13, 14, 18, 19}, {9, 2, 6, 1}, {32, 17, 21, 54}]

## Explanation

• A method named ‘common_elem_set’ is defined which takes a list as parameter.

• The list is iterated over using enumerate.

• A condition is set using ‘&’ and if it is fulfilled, the output is returned.

• Outside the method, a list of list is defined.

• It is displayed on the console.

• It is converted to a set using the ‘map’ method, and then converted to a list again.

• This is assigned to a variable.

• Now the method is called by passing this variable.

• The output is displayed on the console.

Published on 15-Sep-2021 11:35:21