Get loop count inside a Python FOR loop

296
votes

In a Python for loop that iterates over a list we can write:

for item in list:
    print item

and it neatly goes through all the elements in the list. Is there a way to know within the loop how many times I've been looping so far? For instance, I want to take a list and after I've processed ten elements I want to do something with them.

The alternatives I thought about would be something like:

count=0
for item in list:
    print item
    count +=1
    if count % 10 == 0:
        print 'did ten'

Or:

for count in range(0,len(list)):
    print list[count]
    if count % 10 == 0:
        print 'did ten'

Is there a better way (just like the for item in list) to get the number of iterations so far?

5
pythonfor-loop
You might also be interested in the answers to iterating over a list in chunks: stackoverflow.com/questions/434287/… – Dave Bacher
possible duplicate of Accessing the index in Python for loops – Ciro Santilli 新疆再教育营六四事件法轮功郝海东

5 Answers

663
votes

The pythonic way is to use enumerate:

for idx,item in enumerate(list):
102
votes

Agree with Nick. Here is more elaborated code.

#count=0
for idx, item in enumerate(list):
    print item
    #count +=1
    #if count % 10 == 0:
    if (idx+1) % 10 == 0:
        print 'did ten'

I have commented out the count variable in your code.

1
votes

I know rather old question but....came across looking other thing so I give my shot:

[each*2 for each in [1,2,3,4,5] if each % 10 == 0])
1
votes

Using zip function we can get both element and index.

countries = ['Pakistan','India','China','Russia','USA']

for index, element in zip(range(0,countries),countries):

         print('Index : ',index)
         print(' Element : ', element,'\n')

output : Index : 0 Element : Pakistan ...

See also :

Python.org

0
votes

Try using itertools.count([n])