Combining For Loop in Python

Question

suppose message = 1 and contact A in the file and I want to print

1 A
2 B
3 C
4 D

for message in peoplename:
    for contact in contacts_list:
        time.sleep(10)
        print (message, contact)

but it printing like this

1 A
1 B
1 C
1 D
2 A
2 B
2 C
2 D
3 A
3 B
3 C
3 D
4 A
4 B
4 C
4 D

please let me know how to fix it..

zvone · Accepted Answer · 2018-06-10T15:25:51.560

2

It looks like you want to match the first item in peoplename with the first item in contacts_list, second with the second etc. You do that using function zip:

for message, contact in zip(peoplename, contacts_list):
    time.sleep(10)
    print (message, contact)

edited Jun 10 '18 at 15:25

answered Jun 10 '18 at 15:24

zvone

18,045
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not working as well using Zip or iter tools – user3416720 Jun 10 '18 at 15:25
@user3416720 In that case, provide enough information for us to be able to reproduce. See https://stackoverflow.com/help/mcve – zvone Jun 10 '18 at 15:27

score 1 · Answer 2 · answered Jun 10 '18 at 15:26

1

Try the following using zip:

message = [1,2,3,4]
people = ['A','B','C','D']
for x,y in zip(message,people):
  print(x,y)
#Prints
1 A
2 B
3 C
4 D

You can run Live

answered Jun 10 '18 at 15:26

Md Johirul Islam

5,042
4
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score 1 · Answer 3 · answered Jun 10 '18 at 15:26

1

You could iterate over the lists' length instead.

length = len(peoplename)
if legnth != len(contacts_list):
    raise ValueError("Lists have different lengths")

for i in range(length):
    time.sleep(10)
    print (peoplename[i], contact_list[i])

answered Jun 10 '18 at 15:26

Mureinik

297,002
52
306
350

2

That does the same thing as `zip`, but uglier... – zvone Jun 10 '18 at 15:27
2

@ᴀʀᴍᴀɴ What? How could it be more readable to reimplement zip in every place where you need it, instead of using the built-in function which everyone who ever used python understands?! – zvone Jun 10 '18 at 15:30

Combining For Loop in Python

3 Answers3