Reverse grep
Find which pattern matches x.
rgrep(pattern, x, ignore.case = FALSE, perl = FALSE, value = FALSE, fixed = FALSE, useBytes = FALSE, invert = FALSE)
1. np <- length(pattern)
2. g. <- rep(NA, np)
3. for(i in seq(length=np)){
g.[i] <- (length(grep(pattern[i], x))>0)
}
4. return(which(g.))
an integer vector of indices
of elements of pattern with a match
in x.
Spencer Graves
## ## 1. return index ## dd <- data.frame(a = gl(3,4), b = gl(4,1,12)) # balanced 2-way mm <- model.matrix(~ a + b, dd) b. <- rgrep(names(dd), colnames(mm)[5]) # check all.equal(b., 2) ## ## 2. return value ## bv <- rgrep(names(dd), colnames(mm)[5], value=TRUE) # check all.equal(bv, 'b')
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