CODEWITHSUNDEEP
arraysrsamplesub-array
compbiostats
compbiostats

Reputation: 993

Averaging over character arrays in R

I have two character subarrays as follows:

, , 1

    [,1] [,2] [,3] [,4] [,5]
[1,] "5"  "3"  "1"  "1"  "5" 
[2,] "4"  "1"  "1"  "1"  "3" 
[3,] "5"  "5"  "4"  "5"  "1" 
[4,] "5"  "5"  "1"  "3"  "5" 
[5,] "3"  "4"  "1"  "4"  "5" 
[6,] "2"  "5"  "4"  "5"  "2" 
[7,] "2"  "5"  "5"  "4"  "2" 
[8,] "5"  "5"  "2"  "2"  "2" 
[9,] "2"  "5"  "4"  "5"  "4" 
[10,] "2"  "2"  "5"  "2"  "1" 

, , 2

    [,1] [,2] [,3] [,4] [,5]
[1,] "2"  "2"  "2"  "4"  "5" 
[2,] "3"  "1"  "2"  "1"  "4" 
[3,] "5"  "2"  "3"  "4"  "4" 
[4,] "3"  "3"  "4"  "5"  "3" 
[5,] "2"  "1"  "5"  "1"  "3" 
[6,] "5"  "5"  "2"  "5"  "4" 
[7,] "1"  "5"  "1"  "3"  "4" 
[8,] "1"  "5"  "3"  "3"  "5" 
[9,] "4"  "5"  "1"  "1"  "2" 
[10,] "5"  "1"  "2"  "3"  "5"

Now I have written an R routine to randomly sample a row from ONE of these arrays (either ,,1 or ,,2).

But what I would instead like to do is sample randomly from BOTH subarrays and take the column-wise mean. Can I accomplish this without converting from character to numeric values first?

So, if row 1 is sampled in both ,,1 and ,,2, the columnwise mean (rounded appropriately) would be (not done in R)

  "(5+2)/2", "(3+2)/2", "(1+2)/2", "(1+4)/2", "(5+5)/2"
= "4", "3", "2", "3", "5"

My (partial) routine for the random sampling of a row from ONE array is below. I want to modify it for TWO arrays.

for(k in specs){
    for(j in 1:perms){
        for(i in 1:K){
            ind.index <- sample(specs, size = k, replace = FALSE) 
            hap.plot <- pop[sample(1:nrow(pop), size = 1, replace = TRUE), ind.index, sample(i, size = 1, replace = TRUE)]
            HAC.mat[j, k, i] <- length(unique(hap.plot))
    }
  }
}

Any assistance is greatly appreciate.

Please let me know if more clarification is required.

Upvotes: 0

Views: 58

Answers (2)

akrun
akrun

Reputation: 887421

We can use apply

i1 <- sample(seq_len(dim(ar1)[1]), 2)
apply(ar1[i1,,], c(1, 2), FUN = function(x) mean(as.numeric(x)))

Or use rowMeans by looping through the third dimension

rowMeans(apply(ar1[i1,,], 3, FUN = function(x) as.numeric(x)))

data

set.seed(24)
ar1 <- array(as.character(sample(1:5, 10*5*2, replace = TRUE)), dim = c(10, 5, 2))

Upvotes: 1

kangaroo_cliff
kangaroo_cliff

Reputation: 6222

Test data

mat <- array(as.character(1:40), c(15, 5, 2))

Randomly sample from each separately and get the mean.

n_row <- dim(mat)[1]
s_rows <- sample(1:n_row, 2, replace = TRUE)

unlist(lapply(mat[s_rows[1],, 1], as.numeric))/2 + 
  unlist(lapply(mat[s_rows[2],, 2], as.numeric))/2

Upvotes: 1

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