python remove leading negative sign in string

Question

I want to test if a string has a negative leading character, and then delete that character if True.

I've tried:

value_a = "-50.1342"
temp_a = value_a.split(".") #needed for other purposes
if temp_a[0].startswith('-'):
  del temp_a[0]

print temp_a

The result is an empty []. What could be the reason...?

You're deleting the list, that's why it's empty. Try replacing '- 'with '' — Ashutosh, Feb 20 '18 at 20:01
You're deleting the whole first element of the list. I think you meant to do `del temp_a[0][0]`, but that will result in an error because strings are immutable. Change that line to `temp_a[0] = temp_a[0][1:]` instead. [More on python's slice notation](https://stackoverflow.com/questions/509211/understanding-pythons-slice-notation). — pault, Feb 20 '18 at 20:02
JordanCamilletti sry that's a mistake it shouldn't be. @pault thanks this worked! — Yafim Simanovsky, Feb 20 '18 at 20:12
Don't be sry, correct it if it is not relevant to your question! There is an [edit] button just for that. — Jongware, Feb 20 '18 at 21:20

Rafael Barros · Answer 1 · 2018-02-20T21:13:27.110

2

You have a list containing 1 element, the string "-50".

What you want to do is mutate that string, like this:

temp_a[0] = temp_a[0].replace("-", '')

edited Feb 20 '18 at 21:13

answered Feb 20 '18 at 20:04

Rafael Barros

2,738
1
21
28

2

This value would need to be reassigned. Strings are immutable. – whackamadoodle3000 Feb 20 '18 at 20:39
@ᴡʜᴀᴄᴋᴀᴍᴀᴅᴏᴏᴅʟᴇ3000 oops – Rafael Barros Feb 20 '18 at 21:14

RithvikK · Answer 2 · 2018-02-20T21:25:13.717

The output is zero because when you do del temp_a[0] You are not deleting the negative you are deleting the -50. So once you print it It makes it zero. This is shown in the repl.it - https://repl.it/@RithvikKasarla/VapidExternalRuntimes

To make it delete the negative try something like this.

value_a = "-50.1342"
temp_a = value_a.split(".") #needed for other purposes
if temp_a[0].startswith('-'):
  temp_a[0] = str(int(temp_a[0])*-1)
print temp_a

Doing this makes the output ["50","1342"]

score 1 · Answer 3 · answered Feb 20 '18 at 20:12

1

From your description, it sounds like this might be what you want.

value_a = "-50.1342"
temp_a = value_a.split(".") #needed for other purposes

if temp_a[0][0] == '-':
    temp_a[0] = temp_a[0][1:]

print temp_a

This gives me

['50', '1342']

answered Feb 20 '18 at 20:12

ColonelFazackerley

909
6
17

score 0 · Answer 4 · answered Feb 20 '18 at 20:04

0

Try this:

value_a = "-50.1342"
value_a=value_a.replace("-",'')

Which will remove it given that value_a is a number.

answered Feb 20 '18 at 20:04

whackamadoodle3000

6,684
4
27
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python remove leading negative sign in string

4 Answers4