re problem

[Brian Quinlan]

> hi
> i am trying to create an re expression which will match y = mx + c,
> with m and c = a number upto 4 digits long. I first came up with
> 
> self.linear = re.compile("y = [\d+?]x [+|-] \d+", re.IGNORECASE)
> 
> this doesnt work though and i dont understand why.
> thanks

Well, first off you are using "[", which is for character sets, not
matching. Here is a start for you:

linear = re.compile("y \s* = \s* (\d*)x \s* ([+-]\s*\d+)", re.IGNORECASE
| re.VERBOSE)
>>> linear.match('y=2x+3').groups()
('2', '+3')
>>> linear.match('y=x-7').groups()
('', '-7')
>>> linear.match('y = 2322x - 7').groups()
('2322', '- 7') # notice internal space

I don't really understand what you are trying for:
1. can m be negative?
2. can there be a decimal point in m or c?

Cheers,
Brian