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MAT <- matrix(1:40, nrow = 8)
MAT
#> [,1] [,2] [,3] [,4] [,5]
#> [1,] 1 9 17 25 33
#> [2,] 2 10 18 26 34
#> [3,] 3 11 19 27 35
#> [4,] 4 12 20 28 36
#> [5,] 5 13 21 29 37
#> [6,] 6 14 22 30 38
#> [7,] 7 15 23 31 39
#> [8,] 8 16 24 32 40
auc <- seq(1, 5, 2)
#with loop
Vals <- vector("numeric", length = length(auc))
for(i in seq_along(auc)) {
Vals[i] <- MAT[2, auc[i]]
}
df <- as.data.frame(Vals)
df
#> Vals
#> 1 2
#> 2 18
#> 3 34
#without loop
Row2 = MAT[2, auc]
df2 <- as.data.frame(Row2)
df2
#> Row2
#> 1 2
#> 2 18
#> 3 34
Created on 2019-07-10 by the reprex package (v0.2.1)