Matched looping in python

Question

This is probably a very easy thing to solve in Python, but I would appreciate anyone's help. I have two lists where I want to loop through but only for matched items:

lista = ['a', 'b', 'c']
listb = ['a1', 'b1', 'c1']


for a in lista:
    for b in listb:
        print 'my first item is:', a, 'and my second item is:', b

This will print

my first item is: a and my second item is: a1
my first item is: a and my second item is: b1
my first item is: a and my second item is: c1
my first item is: b and my second item is: a1
my first item is: b and my second item is: b1
my first item is: b and my second item is: c1
my first item is: c and my second item is: a1
my first item is: c and my second item is: b1
my first item is: c and my second item is: c1

How can I make it print only:

my first item is: a and my second item is: a1
my first item is: b and my second item is: b1
my first item is: c and my second item is: c1

score 0 · Answer 1 · answered Jun 28 '18 at 06:21

0

This solution assumes both lists are of equivalent size.

for i in range(0, len(lista)):
    print lista[i], listb[i]

answered Jun 28 '18 at 06:21

James

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I should add there are more "Pythonic solutions" to your question but this will help with your understanding. – James Jun 28 '18 at 06:22

score 0 · Answer 2 · answered Jun 28 '18 at 06:21

0

You're looking for zip. It will return an iterator of tuples of each pair of elements.

>>> for z in zip(lista, listb):
...   print('my items are: {}, {}'.format(*z))
...
my items are: a, a1
my items are: b, b1
my items are: c, c1

answered Jun 28 '18 at 06:21

dimo414

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18
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score 0 · Answer 3 · answered Jun 28 '18 at 06:22

0

Try using zip. What zip does is it maps items in your lists. For for e.g. items at index 0 after zip will be (a,a1) and so on.

lista = ['a', 'b', 'c']
listb = ['a1', 'b1', 'c1']
for a in zip(lista,listb):
    print ('my items are:', a)

answered Jun 28 '18 at 06:22

Raghav Patnecha

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what if i need to put the two items in two separate places. for example: print 'my first item is:', a, 'and my second item is:', b – RJL Jun 28 '18 at 06:29
Just add another variable in the for loop and print it – Raghav Patnecha Jun 28 '18 at 08:38

score 0 · Accepted Answer · answered Jun 28 '18 at 06:23

you can use zip to loop over two list simultaneously

lista = ['a', 'b', 'c']
listb = ['a1', 'b1', 'c1']


for a,b in zip(lista,listb):
    print 'my items are:', a, b

output :

my items are: a a1
my items are: b b1
my items are: c c1

according to index matching will be done!

Matched looping in python

4 Answers4