R help - Mar 2014 - Pattern Matching

Suppose I have a character vector as follows:
> aa
[1] "1 (472)" "2 (445)" "3 (431)" "3
(431)" "5 (415)" "6 (405)" "7 (1)”

I want to extract the values within parentheses and place them into a column
that is numeric. The values in aa vary in length and so using strsplit() won’t
work because the positions change. Is there are better pattern matching function
that I can use to grab values from within the parentheses?


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Try

as.numeric(sub(".*\\(","",
sub('\\)','',aa)))

You may also want to look at regexec/regmatches for a more general approach ...

On 02 Mar 2014, at 20:55, Doran, Harold <HDoran@air.org> wrote:
> "1 (472)" "2 (445)" "3 (431)" "3
(431)" "5 (415)" "6 (405)" "7 (1)”
Benno Pütz
Statistical Genetics
MPI of Psychiatry
Kraepelinstr. 2-10
80804 Munich, Germany
T: ++49-(0)89-306 22 222
F: ++49-(0)89-306 22 601




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Hi,
You could try:
as.numeric(gsub(".*[(]([0-9]+)[)]","\\1",aa))
#[1] 472 445 431 431 415 405?? 1
#or


library(gsubfn)
?strapply(aa,"[(]([0-9]+)[)]",as.numeric,simplify=TRUE)
#[1] 472 445 431 431 415 405?? 1

A.K.




On Sunday, March 2, 2014 2:57 PM, "Doran, Harold" <HDoran at
air.org> wrote:
Suppose I have a character vector as follows:
> aa
[1] "1 (472)" "2 (445)" "3 (431)" "3
(431)" "5 (415)" "6 (405)" "7 (1)?

I want to extract the values within parentheses and place them into a column
that is numeric. The values in aa vary in length and so using strsplit() won?t
work because the positions change. Is there are better pattern matching function
that I can use to grab values from within the parentheses?


??? [[alternative HTML version deleted]]

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