for loop inside def in python doesn't iterate

Question

passing argeparse as us-east-1,us-east-2,us-east-3

# Setup commandline arguments
parser = argparse.ArgumentParser(description='using Terraform')
parser.add_argument(
    '-r',
    '--region',
    type=str,
    required=True,
    help='Region in which the ec2 need to be created')

and then trying to for loop for in each region

for region_1 in ([region]):
  print(region_1)

for print(region_1) its prininting all the regions but i want it iteration in loop and print one region at a time. please let me know whatcan be done

How come you are enclosing `region` with brackets. No matter what `region` is, that structure of a for loop will only iterate once. Try `for region_1 in region:`? — SyntaxVoid, May 14 '19 at 18:36
How are you calling your program? Is `region` a list, or a string with commas in it? — gen_Eric, May 14 '19 at 18:38

score 2 · Accepted Answer · answered May 14 '19 at 18:40

This answer solves your question if you want to define better how the arguments should be passed.

For example, you should pass it like --region 'us-east-1' 'us-east-2' 'us-east-3'. And define your argument option using nargs like:

parser.add_argument(
    '-r',
    '--region', 
    nargs='+',
    type=str,
    required=True,
    help='Region in which the ec2 need to be created' 
)

In your case if you want to have a string separated by comma just do:

for r in region.split(","):
  print(r)

score 2 · Answer 2 · answered May 14 '19 at 19:00

You could do it by using nargs for the -r/--regions in argparse like,

$ cat arg.py 
import argparse

parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument(
    '-r',
    '--regions', 
    dest='regions',
    nargs='+',
    required=True,
    help='foo bar'
)

args = parser.parse_args()

for region in args.regions:
    print(region)

$ python arg.py -r us_east us_west us_east1
us_east
us_west
us_east1

score 0 · Answer 3 · answered May 14 '19 at 18:36

0

You're iterating over a list that contains one element: region. [region] is a list containing region just like [1] is a list containing a 1.

Don't wrap that variable in another list before iterating it:

for region_1 in region:

answered May 14 '19 at 18:36

Carcigenicate

43,494
9
68
117

for loop inside def in python doesn't iterate

3 Answers3