How to search for multiple conditions in python regex?

Question

I'm writing a helper script for DnD needs, part of the script should accept either integers or dice notation. The latter is in the format of

1d20+4

where I can replace 1, 20 with and natural number, and +4 with any integer. The input can look like

hit +3 damage 1d8+1 hp 3d6+2

And I split it into two list using re. The problem is that when I try to detect both dies and numbers. I know that that to detect a number I need to use

re.listall('[\+\-][0-9]*',input_line)

and to detect a die I need to search for

re.listall('[0-9]*d[0-9]*',input_line)

And I'm quite certain that to search for a die with a bonus I need

re.listall('[0-9]*d[0-9]*[\+\-][0-9]*',input_line)

However, I can't figure how to search for a combination of the two. I though about placing them in parenthesis, i.e.

re.listall('([\+\-][0-9]*)([0-9]*d[0-9]*)',input_line)

However, I get an error sre_constants.error: unbalanced parenthesis

which leaves me confused. How can I overcome this?

Julien Spronck · Accepted Answer · 2015-04-06 21:19:20Z

1

I think that what you need is this regular expression:

re.findall('((\d+d\d+)?[\+-]\d+)', input_line)

As a side note, you can use \d instead of [0-9]. So, the second part is the same as in your code. The first part '(\d+d\d+)?' is optional (because of ?) and matches number followed by the letter d followed by a number.

In your example (hit +3 damage 1d8+1 hp 3d6+2), this will match +3, 1d8+1 and 3d6+2

edited Apr 6, 2015 at 21:19

answered Apr 6, 2015 at 21:14

Julien Spronck

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2 Comments

Yotam Over a year ago

Thank you, how can I give the option of two digit number? e.g. hit +12

Julien Spronck Over a year ago

The regex I gave you should already be doing it ... \d+ means 1 or more of [0-9] digits. so it should be matching an optional sequence of [1 or more digits]d[1or more digits], then it matches a + or - sign and then [1 or more digits]

Kasravnd · Accepted Answer · 2015-04-06 21:40:46Z

1

You can use to following regex with re.findall(),Note that as certainly you have a number in your pattern you can put \d{1,} within combinations of word characters and +- :

>>> s ='hit +3 damage 1d8+1 hp 3d6+2'
>>> re.findall(r'([\S+-]*\d{1,}[\S+-]*)+',s)
['+3', '1d8+1', '3d6+2']

Regular expression visualization

Debuggex Demo

answered Apr 6, 2015 at 21:40

Kasravnd

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1 Comment

Yotam Over a year ago

Thanks. How can I handle multi digit numbers? e.g. hit +12

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