remove numbers string python

Question

For my assignment, I have to create a function that returns a new string that is the same as the given string, but with digits removed.

Example: remove digits(’abc123’) would return the string ’abc’.

I have tried almost everything I can think off but it's not working properly :(

def test(str):
    for ch in str:
        num = ['0', '1', '2', '3', '4', '6', '7', '8', '9']
        if ch == num[0]:
            return str.replace(ch, '')
        elif ch == num[1]:
            return str.replace(ch, '')
        elif ch == num[2]:
            return str.replace(ch, '')
        elif ch == num[3]:
            return str.replace(ch, '')
        elif ch == num[4]:
            return str.replace(ch, '')
        elif ch == num[5]:
            return str.replace(ch, '')
        elif ch == num[6]:
            return str.replace(ch, '')
        elif ch == num[7]:
            return str.replace(ch, '')
        elif ch == num[8]:
            return str.replace(ch, '')

I enter test('abc123'), expecting the output to be 'abc'. But instead I get 'abc23' as my output.

In other attempts, same problem:

def test(str):
    for char in str:
        num = ['0', '1', '2', '3', '4', '6', '7', '8', '9']
        if char in list(num):
            return str.replace(char, '', len(str))

I get the same results.

Can anyone help me? It would be greatly appreciated.

It's because you are returning from your funciton when you first encounter a number. `return` stops execution and exits the function! — juanpa.arrivillaga, Oct 06 '16 at 22:25
Also, you can just check if `char in "0123456789"` which will simplify your code. — juanpa.arrivillaga, Oct 06 '16 at 22:26

score 9 · Answer 1 · answered Oct 06 '16 at 22:26

9

Use regex

import re
def test(str):
    string_no_numbers = re.sub("\d+", " ", str)
    print(string_no_numbers)
test('abc123') #prints abc

answered Oct 06 '16 at 22:26

Rafael

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score 2 · Answer 2 · answered Oct 06 '16 at 22:25

2

Use this

string = ''.join([c for c in string if c not in "1234567890"])

answered Oct 06 '16 at 22:25

Pax Vobiscum

2,551
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Prune · Answer 3 · 2016-10-06T22:29:46.160

1

Your second solution is close:

def drop_digits(in_str):
    digit_list = "1234567890"
    for char in digit_list:
        in_str = in_str.replace(char, "")

    return in_str

The original problem is that you return after replacing only the '1' chars.

You can also do this with a list comprehension:

return ''.join([char for char in in_str if not char.isdigit()])

edited Oct 06 '16 at 22:29

answered Oct 06 '16 at 22:25

Prune

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Might want to use a better variable name than the OP ;) – Padraic Cunningham Oct 06 '16 at 22:29
Good point. Changing ... – Prune Oct 06 '16 at 22:30
thanks dude, really apreciate it – MountainSlayer Oct 07 '16 at 00:40

jaypb · Answer 4 · 2016-10-06T23:28:18.033

0

You need to read up on some python basics. The "return" exits your function, so it will only ever modify one entry.

Here's a hint: replace str with an updated copy instead of returning it.

str = str.replace(ch, '')

edited Oct 06 '16 at 23:28

answered Oct 06 '16 at 22:25

jaypb

1,544
10
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As for python basics... we are dealing with a function not a method here. This ain't Java ;) – juanpa.arrivillaga Oct 06 '16 at 22:27
eh, test could be in a class without the "self" argument here, if we are gonna be pedantic ;) – jaypb Oct 06 '16 at 22:28
1

If we want to be *super* pedantic, test is not either because it has a indentation errors. – juanpa.arrivillaga Oct 06 '16 at 22:30
^ definitely gotta agree – jaypb Oct 06 '16 at 22:52

Nf4r · Answer 5 · 2016-10-06T22:29:28.663

-1

def test(string):
    return ''.join((letter for letter in string if not letter.isdigit()))

edited Oct 06 '16 at 22:29

answered Oct 06 '16 at 22:26

Nf4r

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This removes more than just digits. – Prune Oct 06 '16 at 22:28
2

probably want to check `if not letter.isdigit()` – juanpa.arrivillaga Oct 06 '16 at 22:29
I've used `not letter.isdigit()` but thought it will be kind of overkill and changed it to `.isalpha`, but re-changed it now. – Nf4r Oct 06 '16 at 22:30

remove numbers string python

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