masking z values (extract or subset on a 3-d array)
This is driving me nuts. I have a 3-D array that holds x,y,z coordinates from multiple experiments. I need to clean the
data before
making it sp objects. I want to set all z-values < 0 to 0. In a 2-D matrix this is trivial e.g., x[,x[1,]<0] <- 0. But I'm
stumped on how
to do this on a 3-D array without a loop. Given an array: foo <- array(rnorm(24), dim=c(4,3,2)) dimnames(foo) <-
list(NULL,c('x','y','z'),c('Experiment1','Experiment2'))
foo[,'z',] How can I set foo[,'z',]<0 to 0?
a <- array(rnorm(64), c(4,4,4)) inds <- which(a < 0, arr.ind=TRUE) a[inds] <- 0
Thanks, but I'm looking to set only the values from one dimension to zero.
As above, I just want to set the 'z' values to 0 if they are less than one.
This works:
foo <- array(rnorm(24), dim=c(4,3,2))
dimnames(foo) <-list(NULL,c('x','y','z'),c('Experiment1','Experiment2'))
foo[,'z',]
#How can I set foo[,'z',]<0 to 0
for(i in 1:2){
foo[foo[,'z',i]<0,'z',i] = 0
}
foo
But it seems like one should be able to do this with apply or just '['. I'm
at a loss.
-A