[R] string problems ( grep and regepxr)

MMarques Power mmarques at inescporto.pt
Wed Mar 24 12:51:34 CET 2004


Recently working with strings and data
I have found a small problem.

Windows XP
R 1.8.1

Reading data from a "txt file" with readLine.
finding a specific line with "grep" command, all OK.
but here comes the problem...
After finding the correct line(s) i need to find a substring
inside each string.
In this case "tabs" I think it represented by "\t" in the grep command
trying to use grep in each string it only returns 1 ...
Afterwards I tried regexpr command it returns the correct position of the
substring that I am looking for but it only reports the first one.
does regexpr only returns the first one ?


Partial example:

d5 = "load0004   node0014        0.05    0.014583333"
     "load0005   node0017        0.05    0.014583333"
     "load0006   node0019        0.05    0.014583333"

     
>grep("\t",d5[1])
[1] 1
>regexpr("\t",d5[1]
[1] 9
attr(,"match.length")
[1] 1

any idea how to make regexpr return the several substrings ?
or the grep and
Am I missing anything obvious ?

THanks in advance
Marco Marques




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