Find TRUE values in logical vector

DESCRIPTION:

Returns indices of TRUE values in logical vector

USAGE:

which(x, arr.ind = FALSE) 

REQUIRED ARGUMENTS:

x
A logical vector.

OPTIONAL ARGUMENTS:

arr.ind
This affects the output when x is a matrix, array, or object with names. If FALSE then return the vector indices of the TRUE values in as.vector(x). If TRUE and x is a matrix or array then return the row, column, etc. indices of the TRUE. These will be returned in a matrix with one column for each dimension of the input array. If TRUE and x has names, then the appropriate subset of those names will be attached to the output vector.

VALUE:

Returns the positions of the TRUE values in x.

SEE ALSO:

EXAMPLES:

x <- c(10,20,30,NA,40) 
which(x>=30) 
# expect to get [1] 3  5 
x[which(x>=30)] 
# expect to get [1] 30 40 
which( cbind(c(T,F,F), c(F,F,T)), arr.ind=T)
# expect to get
#        row col
#   [1,]   1   1
#   [2,]   3   2