python iterate backwards code example

Example 1: python for loop backwards

for i in range(len(item)-1, -1, -1):
        print(item[i])

Example 2: reverse for loop python

# 1.
for i in reversed(range(3)): # output: 	0
    print(i)				 #			1
    						 # 			2
# works with arrays as well , reversed(arr)

# 2.
# another alternative is
arr = [1,2,3]
# note: arr[start : end : step]
for i in arr[::-1]:			 # output:	0
  print(i)					 # 			1
  							 #			2

# 3.
# last alternative i don't recommened!
# note: range(start, end, step)
for i in range(len(arr) - 1, -1 , -1): 	# output: 	0
  print(i)								# 			1
  										# 			2
# read more on range() to understand even better how it works has the same rules as the arrays

Example 3: python for loop reverse

my_list = [1, 2, 3]
my_list.reverse()           # my_list is modified
print(my_list)              # '[3, 2, 1]'
my_revert = my_list[::-1]   # my_list stays [3, 2, 1]
print(my_revert)            # '[1, 2, 3]'
# Item by item reverse with range(<start>, <end>, <step>)
for i in range(len(my_list), 0, -1):		# my_list is [3, 2, 1]
    print(my_list[i-1])		# '1' '2' '3'
for i in reversed(range(len(my_list))):
    print(my_list[i])       # '1' '2' '3'

Example 4: python iterate backwards through list

>>> a = ["foo", "bar", "baz"]
>>> for i in reversed(a):
...     print(i)
... 

or

>>> for i, e in reversed(list(enumerate(a))):
...     print(i, e)

Example 5: how to count backwards in for loop python

# for i in range(start, end, step)
for i in range(5, 0, -1):
    print(i)
5
4
3
2
1

Example 6: iterate backwards through a list python

a = ["foo","bar","baz"]
for i in range(len(a)-1,-1,-1):
  print(a[i])