Counting occurrencies by row - r

Question

Imagine I have a data.frame (or matrix) with few different values such as this
test <- data.frame(replicate(10,sample(c(-1,0,1),20, replace=T, prob=c(0.2,0.2,0.6))))
test2 <- test
If I want to add extra columns with counts I could do:
test2$good <- apply(test,1, function(x) sum(x==1))
test2$bad <- apply(test,1, function(x) sum(x==-1))
test2$neutral <- apply(test,1, function(x) sum(x==0))
But If I had many possible values instead I would have to create many lines, it won't be elegant.
I've tried with table(), but the output is not easily usable
apply(test,1, function(x) table(x))
and there is a big problem, if any row doesn't contain any occurrency of some factor the result generated by table() doesn't have the same length and it can't be binded.
Is there way to force table() to take that value into account, telling it has zero occurrencies?
Then I've thought of using do.call or lapply and merge but it's too difficult for me.
I've also read about dplyr count but I have no clue on how to do it.
Could anyone provide a solution with dplyr or tidyr?
PD: What about a data.table solution?

Answer 1

We could melt the dataset to long format after converting to matrix, get the frequency using table and cbind with the original dataset.
library(reshape2)
cbind(test2, as.data.frame.matrix(table(melt(as.matrix(test2))[-2])))
Or use mtabulate on the transpose of 'test2' and cbind with the original dataset.
library(qdapTools)
cbind(test2, mtabulate(as.data.frame(t(test2))))
Or we can use gather/spread from tidyr after creating row id with add_rownames from dplyr
library(dplyr)
library(tidyr)
add_rownames(test2) %>%
gather(Var, Val, -rowname) %>%\
group_by(rn= as.numeric(rowname), Val) %>%
summarise(N=n()) %>%
spread(Val, N, fill=0) %>%
bind_cols(test2, .)

Answer 2

you can use rowSums():
test2 <- cbind(test2, sapply(c(-1, 0, 1), function(x) rowSums(test==x)))
similar to the code in the comment from etienne, but without the call to apply()

Answer 3

Here is the answer using base R.
test <- data.frame(replicate(10,sample(c(-1,0,1),20, replace=T, prob=c(0.2,0.2,0.6))))
testCopy <- test
# find all unique values, note that data frame is a list
uniqVal <- unique(unlist(test))
# the new column names start with Y
for (val in uniqVal) {
test[paste0("Y",val)] <- apply(testCopy, 1, function(x) sum(x == val))
}
head(test)
# X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 Y-1 Y1 Y0
# 1 -1 0 1 1 1 0 -1 -1 1 1 3 5 2
# 2 1 -1 0 1 1 -1 -1 0 0 1 3 4 3
# 3 -1 0 1 0 1 1 1 1 -1 1 2 6 2
# 4 1 1 1 1 0 1 1 0 1 0 0 7 3
# 5 0 -1 1 -1 -1 0 0 1 0 0 3 2 5
# 6 1 1 0 1 1 1 1 1 1 1 0 9 1