Table of Contents
In this tutorial, we will learn about the Python list() constructor with the help of examples.
The list()
constructor returns a list in Python.
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'>
1. list() Syntax
The syntax of list()
is:
list([iterable])
2. 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
3. list() Return Value
The list()
constructor returns a list.
- If no parameters are passed, it returns an empty list
- If iterable is passed as a parameter, it creates a list consisting of iterable’s items.
4. 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']
5. 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.
6. 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]
Recommended Reading: Python List
Related posts:
Python Namespace and Scope
Python delattr()
Python setattr()
Python Exception Handling Using try, except and finally statement
Python String rfind()
Python Anonymous / Lambda Function
Python Dictionary values()
Python Program to Find the Sum of Natural Numbers
Python Program to Convert Celsius To Fahrenheit
Python pow()
Python Program to Convert Kilometers to Miles
Python Program to Get a Substring of a String
Python List Comprehension
Python Program to Sort a Dictionary by Value
Python Program to Find Factorial of Number Using Recursion
Python Program to Iterate Over Dictionaries Using for Loop
Python List copy()
Python Program to Merge Two Dictionaries
Python sorted()
Python __import__()
Python Deeper Insights into Machine Learning - Sebastian Raschka & David Julian & John Hearty
Python List pop()
Python Program to Find Armstrong Number in an Interval
Python Program to Print all Prime Numbers in an Interval
Python Program to Get the Last Element of the List
Python String replace()
Python Program to Get Line Count of a File
Python Program to Transpose a Matrix
Python Data Structures and Algorithms - Benjamin Baka
Python String isdecimal()
Python Program to Convert Bytes to a String
Python input()