Python Regex String Replace

Question

I am looking for a way to use Regex to replace a string like this:

The quick #[brown]brown#[clear] fox jumped over the lazy dog.

with

The quick <a style="color:#3B170B">brown<a style="color:#FFFFFF"> fox jumped over the lazy dog.

However the color code is picked out of a like as such

color_list = dict(
                 brown = "#3B170B",
                 .....
                 clear = "#FFFFFF",
                 )

@Eric At this point not much, I have tried using re.sub() however I cannot to my knowledge use re.group() to pull out the partiular name of the color I want. — Blackninja543
– Blackninja543, Commented Dec 4, 2012 at 15:24
Do you have control over your input string? That would be a good situation in which to use string formatting if so. — RocketDonkey
– RocketDonkey, Commented Dec 4, 2012 at 15:25
@RocketDonkey No I don't have control over the input string. — Blackninja543
– Blackninja543, Commented Dec 4, 2012 at 15:26

Steven Rumbalski · Accepted Answer · 2012-12-04 15:51:04Z

2

re.sub is what you need. It takes either a replacement string or a function as its second argument. Here we provide a function because part of generating the replacement string needs is a dictionary lookup.

re.sub(r'#\[(.+?)\]', lambda m:'<a style="color:%s">' % colors[m.group(1)], s)

edited Dec 4, 2012 at 15:51

answered Dec 4, 2012 at 15:35

Steven Rumbalski

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4 Comments

Blackninja543 Over a year ago

I am finding the re.sub function does not seem to work even when I implement something such as re.sub(r'#\[brown\]', colors['brown'], s) which should return the string to The quick brown #3B170Bfox#[clear] jumped over the lazy dog.

Steven Rumbalski Over a year ago

I renamed color_list to colors. Are you forgetting to update that name?

Blackninja543 Over a year ago

No in fact I used a completely different name in my code and was thrown an error to fix it, after the fix there was no change in the string.

Steven Rumbalski Over a year ago

@Blackninja543: Are you assigning the result of re.sub back to your string?

dmoreno · Accepted Answer · 2012-12-04 15:28:05Z

0

Just one line of fine python should help:

reduce(lambda txt, i:txt.replace('#[%s]'%i[0],'<a style="color=%s;">'%i[1]),colors.items(),txt)

answered Dec 4, 2012 at 15:28

dmoreno

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1 Comment

Jakub M. Over a year ago

Looks like Haskell-derived perfectly unreadable one-liner : ) . Although I like the idea

Jakub M. · Accepted Answer · 2012-12-04 17:41:36Z

0

A crude pseudo-python solution would look like this:

for key, value in color_list.items()
  key_matcher = dict_key_to_re_pattern( key )
  formatted_value = '<a style...{0}...>'.format( value )
  re.sub( key_matcher, formatted_value, your_input_string )


def dict_key_to_re_pattern( key ):
   return r'#[{0}]'.format( key )

edited Dec 4, 2012 at 17:41

answered Dec 4, 2012 at 15:24

Jakub M.

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