Add counter in loop python

This (creating an extra variable before the for-loop) is not pythonic .

The pythonic way to iterate over items while having an extra counter is using enumerate:

for index, item in enumerate(iterable):
    print(index, item)

So, for example for a list lst this would be:

lst = ["a", "b", "c"]

for index, item in enumerate(lst):
  print(index, item)

...and generate the output:

0 a
1 b
2 c

You are strongly recommended to always use Python's built-in functions for creating "pythonic solutions" whenever possible. There is also the documentation for enumerate.

If you need more information on enumerate, you can look up PEP 279 -- The enumerate() built-in function.

Count in a for loop in Python #

Use the enumerate() function to count in a for loop, e.g. for index, item in enumerate(my_list):. The function takes an iterable and returns an object containing tuples, where the first element is the index, and the second - the item.

Copied!
my_list = ['a', 'b', 'c']

# ✅ count in for loop

for index, item in enumerate(my_list):
    print(index, item)

# 👇️
# 0 a
# 1 b
# 2 c

# ---------------------------------------------

# ✅ count in for loop starting with N

for count, item in enumerate(my_list, start=1):
    print(count, item)

# 👇️
# 1 a
# 2 b
# 3 c

# ----------------------------------------------

# ✅ manually incrementing counter in for loop

counter = 0

for item in my_list:
    counter += 1
    print(counter)

print(counter)  # 👉️ 3

The enumerate function takes an iterable and returns an enumerate object containing tuples where the first element is the index, and the second - the item.

We can directly unpack the index (or count) and the item in our for loop.

Copied!
my_list = ['a', 'b', 'c']


for index, item in enumerate(my_list):
    print(index, item)

# 👇️
# 0 a
# 1 b
# 2 c

The enumerate function takes an optional start argument, which defaults to 0.

If you need to start the count from a different number, e.g. 1, specify the start argument in the call to enumerate().

Copied!
my_list = ['a', 'b', 'c']


for count, item in enumerate(my_list, start=1):
    print(count, item)

# 👇️
# 1 a
# 2 b
# 3 c

The count variable has an initial value of 1 and then gets incremented by 1 on each iteration.

Alternatively, you can manually count in the for loop.

To count in a for loop:

1. Initialize a count variable and set it a number.
2. Use a for loop to iterate over a sequence.
3. On each iteration, reassign the count variable to its current value plus N.

Copied!
my_list = ['a', 'b', 'c']


count = 0

for item in my_list:
    count += 1
    print(count)

print(count)  # 👉️ 3

We declared a count variable and initially set it to 0.

On each iteration, we use the += operator to reassign the variable to its current value plus N.

The following 2 lines of code achieve the same result:

• count += 1
• count = count + 1

Here is an example that uses the longer reassignment syntax.

Copied!
my_list = ['a', 'b', 'c']


count = 0

for item in my_list:
    count = count + 1
    print(count)

print(count)  # 👉️ 3

How do I set a loop counter in Python?

How do you add a count to a for loop?

How do you add a counter in Python?

How do you increment a counter in a for loop in Python?