The filter() function constructs an iterator from elements of an iterable for which a function returns true. It is used to filter out items from a list (or any other iterable) based on a condition.
The syntax is similar to map:
filter(func1, iterable)
Examples:
num_list = [i for i in range(1, 13)] # [1, ..., 12]
print(list(filter(lambda x: x%2==0, num_list)))
# output: [2, 4, 6, 8, 10, 12 ]
You can filter with multiple conditions:
num_list = [i for i in range(1,10)] #[1,2,...,9]
even_and_greater_than_five = list(filter(lambda x: x> 5 and x%2==0, num_list))
print(even_and_greater_than_five) # output: [6, 8]
You can perform filter operation on dictionaries:
dict_list = [{'age': 23}, {'age': 15}, {'age': 57}]
print(list(filter(lambda d: d['age'] > 25, dict_list))) # output: [{'age': 57}]