List values to have same width

Question

I have a Python list on int types:

list1 = [1, 2, 3, 4, 10, 100]

I need to get another list of the above list values but with equal width like:

list2 = ['001', '002', '003', '004', '010', '100']

I can do this by looping through list1 values, converting them to strings, finding their lengths and appending 0's in-front of the values but this is a bit long process, is there any better way to do this?

If you know the width up front, then yes... otherwise, no... what you're doing is basically what you need to be doing... — Jon Clements, Aug 07 '19 at 14:03
Possible duplicate of [Display number with leading zeros](https://stackoverflow.com/questions/134934/display-number-with-leading-zeros) — Error - Syntactical Remorse, Aug 07 '19 at 14:07

score 2 · Accepted Answer · answered Aug 07 '19 at 14:02

2

Use str.zfill

Ex:

list1 = [1, 2, 3, 4, 10, 100]
l = len(str(max(list1)))  #Get max width
result = [str(i).zfill(l) for i in list1]
print(result)

Output:

['001', '002', '003', '004', '010', '100']

answered Aug 07 '19 at 14:02

Rakesh

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score 0 · Answer 2 · answered Aug 07 '19 at 14:01

You can use string formatting:

['{:03.0f}'.format(i) for i in list1]
# ['001', '002', '003', '004', '010', '100']

Or if you don't know the max width in adavance, you can use str.rjust:

w = len(max(map(str, list1), key=len))
list2 = [str(i).rjust(w, '0') for i in list1]

List values to have same width

2 Answers2