[R] Replace values on seq
Walter Alini
walteralini at gmail.com
Tue Oct 23 22:17:32 CEST 2007
Hey guys, sorry for the inconvenience (this might be a hundred times
answered question), but I have been searching a while and gave up
about the following:
I have the following, table and data:
table <- seq(255, 0, by=-1)
data <- c(1,8,...) <--- doesn't matter what's in here
Which would be the most efficient way to replace each data value, v_i,
by table[v_i + 1] ?
And, maybe more important, why is that more efficient?
I used this, but I think is not the best option:
for (i in 1:length(data)){
data[i] <- table[data[i]+1]
}
Then used mapply, that seems to work better:
f<-function(x){
255-x
}
mapply(f, data)
Thanks guys in advance,
Walter
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