Write and read 3D arrays in R

Question

I have a 3D array in R constructed as (although the names don’t seem to show up):

v.arr <- array(1:18, c(2,3,3), dimnames = c("A", "B", "X",
                          "Y","Z","P","Q","R"))

and it shows up like this when printed to the screen:

, , 1

     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    2    4    6

, , 2

     [,1] [,2] [,3]
[1,]    7    9   11
[2,]    8   10   12

, , 3

     [,1] [,2] [,3]
[1,]   13   15   17
[2,]   14   16   18

I write it out to a file using:

write.table(v.arr, file = “Test Data”)

I then read it back in with:

test.data <- read.table(“Test Data”)

and I get this:

  X1 X2 X3 X4 X5 X6 X7 X8 X9
1  1  3  5  7  9 11 13 15 17
2  2  4  6  8 10 12 14 16 18

Obviously, I need to do something to either structure the file before writing or restructure it on the read-back to get back the 3D array. I can always restructure the data that I get from reading. Is that the best approach? Thanks in advance.

Answer 1

Your issue is that you are using write.table to do this, so it is (I believe) coercing your array to a table. If you are looking to save it and don't mind that it would be in an R-specific format, you can easily use the save and load functions.

save(v.arr,file = "~/Desktop/v.arr.RData")
rm(list=ls())

load("~/Desktop/v.arr.RData")
v.arr