The list() constructor converts an iterable (dictionary, tuple, string etc.) to a list and returns it.
Example
text = 'Python' # convert string to list text_list = list(text) print(text_list) # check type of text_list print(type(text_list)) # Output: ['P', 'y', 't', 'h', 'o', 'n'] # <class 'list'> list() Syntax
The syntax of list() is:
list([iterable])
list() Parameters
The list() constructor takes a single argument:
- iterable (optional) - an object that could be a sequence (string, tuples) or collection (set, dictionary) or any iterator object
list() Return Value
The list() constructor returns a list.
- If no parameters are passed, it returns an empty list
- If an iterable is passed, it creates a list with the iterable's items.
Example 1: Create lists from string, tuple, and list
# empty list print(list()) # vowel string vowel_string = 'aeiou' print(list(vowel_string)) # vowel tuple vowel_tuple = ('a', 'e', 'i', 'o', 'u') print(list(vowel_tuple)) # vowel list vowel_list = ['a', 'e', 'i', 'o', 'u'] print(list(vowel_list)) Output
[] ['a', 'e', 'i', 'o', 'u'] ['a', 'e', 'i', 'o', 'u'] ['a', 'e', 'i', 'o', 'u']
Example 2: Create lists from set and dictionary
# vowel set vowel_set = {'a', 'e', 'i', 'o', 'u'} print(list(vowel_set)) # vowel dictionary vowel_dictionary = {'a': 1, 'e': 2, 'i': 3, 'o':4, 'u':5} print(list(vowel_dictionary)) Output
['a', 'o', 'u', 'e', 'i'] ['o', 'e', 'a', 'u', 'i']
Note: In the case of dictionaries, the keys of the dictionary will be the items of the list. Also, the order of the elements will be random.
Example 3: Create a list from an iterator object
# objects of this class are iterators class PowTwo: def __init__(self, max): self.max = max def __iter__(self): self.num = 0 return self def __next__(self): if(self.num >= self.max): raise StopIteration result = 2 ** self.num self.num += 1 return result pow_two = PowTwo(5) pow_two_iter = iter(pow_two) print(list(pow_two_iter)) Output
[1, 2, 4, 8, 16]
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