Python For-Each Loop

In python programming language, thepython for-each loop is another variation of for loop structure. In this loop structure, you get values from a list, set and assign it to a variable during each iteration.

It is little hard to understand without an example. Consider the usual way to using for loop.

for i in range(1,11):
     print(i)

The above construct is useful and variable i can be used as an index to a set or list and solve a problem.

Consider the following example.

my_list = [23, 66, 68, 88, 19]
sum = 0
# now we will use i as an index for the list items
for i in range(0,5):
    sum = sum + my_list[i]
print(sum/5)

In the program above, the sum is 0. The variable i used as index to my_list and adds each item to sum during an iteration.

================ RESTART: C:\Python_projects\For-Each_Loop.py ================
52.8
>>> 

The final value is sum of all number which is divided by 5 to get the average.

For-Each Loop

The for-each loop can be written as follows.

my_list = [55,66,77,88,99]
for list_item in my_list:
    print(list_item)

The value of list is assigned to list_item during the iteration and it printed in the next line.

================ RESTART: C:/Python_projects/For-Each_Loop.py ================
55
66
77
88
99
>>> 

The for-each loop gives an opportunity to go through each item without skipping an member. The range of the loop depends on the set or the list.

A for-each loop can do everything that a traditional for loop can do. Consider the example, where we have modified the average finding program using for loop.

my_list = [55, 66, 77, 88, 99]
sum = 0
# take a sum of the numbers in the list
for list_item in my_list:
   sum = sum + list_item
print(sum/5)

The program does everything that a traditional loop would do and take an average. The range() function is replaced with the my_list.

============= RESTART: C:\Python_projects\For-each_average_2.py =============
77.0
>>> 

Note that the loop will run until it has finished adding each item to the sum.