Python loop through list

In this post, you will learn how to loop through a list using the Python programming language.

A list is a sequence of indexed and ordered values, like a dynamic size array. It is mutable, which means we can change the order of elements in a list. It contains a list of any type of data object with a comma separated and enclosed within a square bracket. The elements in a list are indexed, starting with 0 , 1, and so on. In the development process, we may come to the situation where we need to loop through the list. Generally, developers use simple for and while loops when iterating through various kinds of iterators, but Python provides a lot of helper functions that can make your code simpler and even faster. Here, we have mentioned most of them with simple examples.

Python loop through list using for loop without index

For loop is available in almost every programming language. The Python for loop is used to loop through an iterable object, like a list, tuple, set, etc. In the given Python program, we have used a for loop to iterate over a list without displaying the index value.

# Python code to iterate over a list
# using for loop
list_elems = ['bread', 'cookies', 'chocolate', 'tea', 'cake']

# Iterate over the list
for value in list_elems :
   print(value, end=' ')

bread cookies chocolate tea cake

Python loop through list using for loop with index

In the given Python program, we have used a for loop to iterate over a list and displaying their index value.

list_elems = ['bread', 'cookies', 'chocolate', 'tea', 'cake']

# Iterate over the list
for value in range(0,len(list_elems)): 
   print(value, end=' ')

0 1 2 3 4

Python loop through list using for loop with enumerate type

Python enumerate() function can be utilised to repeat the list in an enhanced way. This method adds a counter to the iterator and returns it (the enumerate object). It makes it simpler to monitor the substance of an iterable article. Subsequently, it reduces the overhead of keeping a check of the components during the iteration operation. Here, we have used a for loop with enumerate type to iterate over a list.

list_elems = ['chair', 'fan', 'bulb', 'table', 'cooler']

# Iterate over the list
for value,char in enumerate(list_elems):
   print(char, end=' ')

chair fan bulb table cooler

Python loop through list using for loop with sliced lists

In the given Python program, we have iterated over the list elements with sliced lists.

list_elems = ['bread', 'cookies', 'chocolate', 'tea', 'cake']

# Iterate over the list
for value in range(1,len(list_elems)):
   print(list_elems[value-1:value], end='')
print(list_elems[-1:])

['bread']['cookies']['chocolate']['tea']['cake']

Python loop through list using while loop

The while loop is used to repeat a section of code an unknown number of times until a specific condition is met. Here, we have used a while loop to iterate over the given list.

list_elems = ['bread', 'cookies', 'chocolate', 'tea', 'cake']

# Getting length of list
length = len(list_elems )
i = 0
  
# Iterating using while loop
while i < length:
    print(list_elems [i])
    i += 1

bread
cookies
chocolate
tea
cake

Python loop through list using for loop and range

The range() method of Python is helpful while dealing with loops, conditional statements. It returns a sequence of numbers, starting from 0 by default and incrementing by 1 (by default), and stops before a specified number. We can use Python's range() method in combination with a for loop to iterate over a list.

# Python code to iterate over a list
list_elems = ['bread', 'cookies', 'chocolate', 'tea', 'cake']

# getting length of list
length = len(list_elems )
  
# Iterating the index
# same as 'for i in range(len(list_elems))'
for i in range(length):
    print(list_elems[i])

bread
cookies
chocolate
tea
cake

Python loop through list using a lambda function

Lambda is an anonymous function that contains any number of arguments but only one expression. This function is defined without a name. Here, we have used the lambda function to loop over the list.

list_elems = [42, 74, 22, 65, 23, 52]

y = list(map(lambda x:x, list_elems))
 
print(y) 

[42, 74, 22, 65, 23, 52]

Python loop through list using Python numpy

NumPy is an open-source numerical Python library. It provides an efficient multi-dimensional iterator object called np.nditer to iterate over arrays. Here is an example-

import numpy as np
 
list_elems = ['bread', 'cookies', 'chocolate', 'tea', 'cake']
  
for x in np.nditer(list_elems): 
    print(x) 

(array('bread', dtype='<U5'), array('cookies', dtype='<U7'), array('chocolate', dtype='<U9'), array('tea', dtype='<U3'), array('cake', dtype='<U4'))

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