Indicator matrix for non-exclusive factors

Question

Say I have a list containing vectors of factors:

colors <- c("red", "green", "blue")
f <- factor(colors, levels=colors)
rgb <- sapply(sample(1:3, 5, replace=TRUE), function(n) sample(f, n))

Which might look like this:

> invisible(sapply(rgb, function(x) print(x, max.levels=0)))
[1] blue  green
[1] red
[1] blue  red   green
[1] red   blue  green
[1] blue

How can I construct a matrix of indicator values that represent the same information:

     [,1] [,2] [,3]
[1,]    0    1    1
[2,]    1    0    0
[3,]    1    1    1
[4,]    1    1    1
[5,]    0    0    1

While my question may be similar to the one linked, I believe @akrun's solves my problem significantly more simply than any of the answers in the other question. — user12341234, Jan 16 '17 at 06:46

score 2 · Accepted Answer · answered Jan 16 '17 at 06:04

2

We can use table

t(sapply(rgb, table))

answered Jan 16 '17 at 06:04

akrun

1 Answers1