Reshape three column data frame to matrix (“long” to “wide” format) [duplicate]

Answer 1

For sake of completeness, there's a tapply() solution around.

with(d, tapply(z, list(x, y), sum))
#   a b c
# x 1 2 3
# y 3 3 2

Data

d <- structure(list(x = structure(c(1L, 1L, 1L, 2L, 2L, 2L), .Label = c("x", 
"y"), class = "factor"), y = structure(c(1L, 2L, 3L, 1L, 2L, 
3L), .Label = c("a", "b", "c"), class = "factor"), z = c(1, 2, 
3, 3, 3, 2)), class = "data.frame", row.names = c(NA, -6L))