How to get kth smallest value for each row (excluding NA) of data.frame

Alex Braksator 0
Viewed 29

Given a data.frame like the one below, how do I find the kth largest value for each row from a range of columns:

Input:

ID i1 i2 i3
1 NA NA NA
1 0 NA NA
1 1 0 NA
1 1 1 NA
1 0 1 NA
1 0 1 2

Desired Output:

ID i1 i2 i3 k=1 k=2 k=3
1 NA NA NA NA NA NA
1 0 NA NA 0 NA NA
1 1 0 NA 0 1 NA
1 1 1 NA 1 1 NA
1 0 1 NA 0 1 NA
1 2 1 0 0 1 2

I would like a solution that works with three columns like above (i1,i2,i3) but can also work for a dataframe with say 6 columns named (i1,i2,i3,i4,i5,i6) and more potentially. Assume these columns are always adjacent to each other and named like how I have them

dplyr r
1 Answers

If it is to sort by row and create new columns

m1 <- t(apply(df1[-1], 1, function(x) sort(x, na.last = TRUE)))
df1[paste0("k=", seq_len(ncol(m1)))] <- m1

-output

> df1
  ID i1 i2 i3 k=1 k=2 k=3
1  1 NA NA NA  NA  NA  NA
2  1  0 NA NA   0  NA  NA
3  1  1  0 NA   0   1  NA
4  1  1  1 NA   1   1  NA
5  1  0  1 NA   0   1  NA
6  1  0  1  2   0   1   2

data

df1 <- structure(list(ID = c(1L, 1L, 1L, 1L, 1L, 1L), i1 = c(NA, 0L, 
1L, 1L, 0L, 0L), i2 = c(NA, NA, 0L, 1L, 1L, 1L), i3 = c(NA, NA, 
NA, NA, NA, 2L)), class = "data.frame", row.names = c(NA, -6L
))
akrun0
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