I would like to sum 5 to each element of an array (not through all dimensions) without using a loop for. As the result, I want to get an array with the exact same dimensions, but each element should have 5 added to it. I tried using the sum and the apply functions, but I either get the sum of each of the elements (one number), or this error message:
Error in apply(b[, , , 2], 5, FUN = sum, na.rm = T) :
'MARGIN' does not match dim(X)
I need to have na.rm = T, because there are a lot of NA in my dataset, so I want to get NA + 5 = 5
Here is an example where I'm trying to sum 5 to all dimensions but to [,,,1] :
b <- array(seq(1,48,1), dim = c(4,2,3,2))
b[4,2,3,2] <- NA
I tried:
sum(b[,,,2], 5, na.rm = T)
I was expecting to get as an answer:
(a <- array(c(seq(1,24,1),seq(25,47,1)+5, 5), dim = c(4,2,3,2)))
R by default supports adding to matricies and arrays. You can just use the + operator to add a value to each element of a vector/matrix/array. Since you only want to affect parts of that array, just use square brackets to subset the parts you want to affect:
b[,,,2] <- b[,,,2] + 5
table(b==a, useNA='always')
TRUE <NA>
47 1
You have NA values in your array. In R, by default, operations involving an NA return NA. So in this case, the NA values in b will remain NA after the addition.
If you want different behavior, for example if you want NA + 5 = 5, then you need to convert the NA values to 0 in the parts of the array you care about before doing the addition
To replace all NAs with 0:
b[is.na(b)] <- 0
To only do that in b[,,,2]:
b[,,,2][is.na(b[,,,2])] <- 0