On Jul 2, 2012, at 4:15 AM, Sarah Auburn wrote:
Hello,
I would like to substitute a substring of characters defined by a
specific start and end sequence.
i.e. in the example matrix below, I would like to substitute ".:X:"
with "", where X varies in sequence...
m<-matrix(c(".:0:0,0", ".:2:0,2", ".:194:193,1", ".:56:0,56", ".:
58:50,8", ".:13:0,13", ".:114:114,0", ".:75:75,0"), nrow=2)
sub("\\..+\\:", "", m)
[,1] [,2] [,3] [,4]
[1,] "0,0" "193,1" "50,8" "114,0"
[2,] "0,2" "0,56" "0,13" "75,0"
You should also look at Holtman's since he is better at this than I am
but I didn't really understand how his version worked. Mine is really
in three parts. The first entry '\\.' matches the leading dot and it
could have been '^\\.' to avoid any confusion with decimal points. The
second entry is '.+' which is anything until the third entry '\\:'
which ends up matching the last ':' since these are greedy expressions.
You could also have done it with "\\.\\:.+\\:"
(Now that I look at his again "^\\.:[^:]*:" , I find that I can learn
something from it, as often happens when I read his contributions. To
my surprise the ':' character does not need to be escaped but can be
and the interior of his expression '[^:]' is a negative character-
class. It matches anything other than ':' and the '*' following it
lets that anything be of any length. And then he didn't need to escape
the trailing ':'.)
--
David.
output required:
[,1] [,2] [,3] [,4]
[1,] "0,0" "193,1" "50,8" "114,0"
[2,] "0,2" "0,56" "0,13" "75,0"
Thank you for any help
Sarah
[[alternative HTML version deleted]]
--
David Winsemius, MD
West Hartford, CT
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