How to create lower dimensional matrix from higher dimensional array in R?

Question

Suppose I have an array such that:

temp<-array(0, dim=c(100,10,4))

I can merge matrices 1 & 2 from the array into a single matrix using cbind:

temp.merge<-cbind(temp[,,1],temp[,,2])

Is there a way to merge all n matrices (in this case 4) into a single one without having to write out the position of each one as above?

Answer 1

If you have the array set up right in memory, you can just reset the dimensions and it will work.

dim(temp) <- c(100, 40)

Answer 2

If @Neal's answer works, definately use it.

This also works:

# generates 100 X 40 array
do.call("cbind",lapply(1:4,function(x){return(temp[,,x])}))

You would think that:

do.call("cbind",list(temp[,,1:4]))    ## generates 4000 X 1 array

would work, but it does not...

Answer 3

Also:

as.matrix(as.data.frame(temp))

Example:

> temp <- array(1:8, dim=c(2,2,2))
> temp
#, , 1
# 
#     [,1] [,2]
#[1,]    1    3
#[2,]    2    4
#
#, , 2
# 
#     [,1] [,2]
#[1,]    5    7
#[2,]    6    8


as.matrix(as.data.frame(temp))

#     V1 V2 V3 V4
#[1,]  1  3  5  7
#[2,]  2  4  6  8