in R: Two Way Match to Matrix

Question

If I have a data.frame

df <- data.frame(DEP=letters[1:5], ARR=letters[11:15], NO=1:5+5)

   DEP ARR  NO
1   a   k   6
2   b   l   7
3   c   m   8
4   d   n            


        

Answer 1

If I understood your question correctly, you could use a sparse matrix definition:

library(Matrix)
mat <- spMatrix(length(df$DEP), length(df$ARR), 
                seq(df$DEP), seq(df$ARR), as.numeric(as.character(df$NO)))
rownames(mat) <- df$DEP
colnames(mat) <- df$ARR
#> as.matrix(mat)
#  k l m n  o
#a 6 0 0 0  0
#b 0 7 0 0  0
#c 0 0 8 0  0
#d 0 0 0 9  0
#e 0 0 0 0 10

Answer 2

?xtabs:

xtabs(NO ~ ., data=df)
#   ARR
#DEP  k  l  m  n  o
#  a  6  0  0  0  0
#  b  0  7  0  0  0
#  c  0  0  8  0  0
#  d  0  0  0  9  0
#  e  0  0  0  0 10