create a sample matrix from the main matrix

Question

I want to create a sample matrix from the main one with the sam number of columns but less rows (50) I tried to use a series of loops but it didn't work:

n=nrow(data)
camp <- sample(1:n,size=50,replace=TRUE)


n<-length(camp)
c<-ncol(data)
for(i in 1:n){
      t<-camp[i]
    for(k in 1:c){
    campione[i,k]<-data[t,k]}
}

score 0 · Accepted Answer · answered Mar 31 '17 at 09:27

0

You don't need to use loop. You just have to take random lines from your main matrix:

mat = matrix(runif(2000),ncol=20)

sample_matrix = mat[sample(1:nrow(mat),50),]

answered Mar 31 '17 at 09:27

xraynaud

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create a sample matrix from the main matrix

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