Is there a way to describe a repeating pattern in substitution?

Question

I have multiple numbers in lines of 16, for example

  $02 c, $3f c, $fe c, $01 c, $ff c, $06 c, $00 c, $f8 c, $06 c, $1f c, $fe c, $00 c, $7f c, $8c c, $00 c, $fc c,

with pattern [$][0-9][0-9]\s@, and I need to substitute those lines by grouping the numbers in set of four and adding group after each group, like

 $02 $3f $fe $01 group $ff $06 ...

Is there a short way to do this, or I have to copy and paste same pattern four times in the :s command ?

Edit: the pattern should be: \$\x\x c,, thanks DJMcMayhem

Answer 1

Your regex doesn't seem right. [$][0-9][0-9]\s@, won't match the hex digits (such as 3f), and it seems like there's a c after each number, not an @. Don't you mean they match this pattern?

[$][0-9a-f][0-9a-f]\sc, 

or even simpler

\$\x\x c, 

But anyway, on to your main question. Yes, you can repeat a pattern without having to type it out multiple times. For example:

\(foo\)\{3}

will match "foo" repeated 3 times. I'd recommend reading through quantifiers on vimregex.com.

In your specific example, I'd recommend two regexes. One to remove the "c"s:

:s/ c,//g

Followed by a regex to add the "group" text:

:s/\v(\$\x\x ){4}/&group /g