sapply - Count previous occurences of a string across multiple columns in R -

i have 4 column matrix chronological index, , 3 columns of names (strings). here toy data:

x = rbind(c(1,"sam","harry","joe"), c(2,"joe","sam","jack"),c(3,"jack","joe","jill"),c(4,"harry","jill","joe")) 

i want create 3 additional vectors count (for each row) previous (but not subsequent) occurrences of name. here desired result toy data:

y = rbind(c(0,0,0),c(1,1,0),c(1,2,0),c(1,1,3)) 

i @ loss of how approach problem, , have searched stack overflow relevant examples. dplyr provides answers finding total counts, (as far can tell) not on row row basis.

i attempted write function deal problem in single-column space, no luck, i.e.

thing = sapply(x,function(i)length(grep(i,x[x[1:i]]))) 

any tips appreciated.

this typical ave + seq_along type of problem, need convert data vectors first:

t(`dim<-`(ave(rep(1, prod(dim(x[, -1]))),                c(t(x[, -1])), fun = seq_along)  - 1,            rev(dim(x[, -1])))) #      [,1] [,2] [,3] # [1,]    0    0    0 # [2,]    1    1    0 # [3,]    1    2    0 # [4,]    1    1    3 

---

perhaps more readable:

## x without first column vector x_vec <- c(t(x[, -1]))  ## values looking obtain... y_vals <- ave(rep(1, length(x_vec)), x_vec, fun = seq_along) - 1  ## ... in format want obtain them matrix(y_vals, ncol = ncol(x) - 1, byrow = true) #      [,1] [,2] [,3] # [1,]    0    0    0 # [2,]    1    1    0 # [3,]    1    2    0 # [4,]    1    1    3