Python print one by one list and add count

Question

I'm trying to print a list of objects 1 by one and at the same time print count next to them.

Add something to the code so

for i in items:
    print(i)

returns:

wool
honey

etc.

William Ferreira · Accepted Answer · 2015-12-01T02:03:39.923

The function you are looking for is enumerate

for idx, val in enumerate(items, 1):
    print(idx + '. ' + val)

As suggested by Harvey, enumerate returns a tuple, but str.join only accepts str iterables. If you were iterating over an indexable object whose keys and values were all strings (e.g. a str to str dict), then the code

for idx_val_pair in enumerate(items, 1):
    print('. '.join(idx_val_pair))

would also work.

EDIT: If you're just starting out with Python (which I suppose is the case) then don't worry about the stuff down here, but if you want to keep performance consistence among PyPy and CPython (among others) string concatenation is better done with the join method. The "correct" version of the code above would be

for idx, val in enumerate(items, 1):
    print('. '.join([str(idx), str(val)])

You could add a third example which uses the tuple of index and value directly: `for idx_val in enumerate(items, start=1): print('. '.join(idx_val))` — Harvey, Dec 01 '15 at 01:57

erip · Answer 2 · 2015-12-01T01:57:10.450

2

enumerate gives you the index of the current item returned.

You can use it like this:

# enumerate items, but start counting at 1
for i, j in enumerate(items, 1):
  print("{0}. {1}".format(i, j))

Here's an example usage:

>>> items = ["wool", "honey", "string"]
>>> for i, j in enumerate(items, 1):
...   print("{0}. {1}".format(i, j))
... 
1. wool
2. honey
3. string

edited Dec 01 '15 at 01:57

answered Dec 01 '15 at 01:50

erip

13,935
9
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1

Use the start parameter of enumerate: `enumerate(items, start=1)` – Harvey Dec 01 '15 at 01:54
@Harvey Very cool. I didn't know that existed! – erip Dec 01 '15 at 01:57
1

Also, if you never actually use `i` and `j` separately, you could do `for ij in...` `....format(*ij))` – Harvey Dec 01 '15 at 01:59
Not as readable, but still noted. – erip Dec 01 '15 at 02:10

score 1 · Answer 3 · answered Dec 01 '15 at 09:43

1

for count, label in enumerate(ls, 1):
    print '%d. %s' % (count, label)

Will produce desired output.

answered Dec 01 '15 at 09:43

Dharmraj

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score 0 · Answer 4 · answered Dec 01 '15 at 01:36

0

How about:

for j in range(len(items)):
    print("%d. %s" % (j+1, items[j]))

answered Dec 01 '15 at 01:36

aghitza

176
3

1

This is not pythonic. – erip Dec 01 '15 at 01:47

vento · Answer 5 · 2015-12-01T05:43:52.173

This is done in python 2.7 and above answers gives already a good solution. As a python beginner I would start with something as simple solution as this. Printing can always be in prettier format, but just to give an idea.

    ls = ['wool','honey','extra']
    count = 0
        for l in ls:
        count+=1
        print str(count)+ '. ' + l

OR like suggested enumerate seems to be the best option

    for count, names in enumerate(ls, start=1): #start =   can be removed
        print str(count)+ '. ' + names

Python print one by one list and add count

5 Answers5