Check if something is in each row (row length>1) - r

Question

Basically I have a matrix and row with a in it I want to append a "1" to a list, otherwise append a "0"
The code is as follows:
is.there.A <- function(a,b,c,d,e) {
library(combinat)
x <- c(a,b,c,d,e)
matrix <- matrix(combn(x,3), ncol=3, byrow=T)
row <- nrow(matrix)
list <- list()
for (i in seq(row)) {
if (matrix[i,] %in% "A") {c(list, "1")}
else {c(list, "0")}
print(list)
}
}
But it doesn't work and this shows up.
Warning messages:
1: In if (matrix[i, ] %in% "A") { :
the condition has length > 1 and only the first element will be used
The question is how to overcome this to achieve the objective

Answer 1

You can avoid your explicit loop by using apply
is.there.A <- function(a,b,s,d,e) {
library(combinat)
x <- c(a,b,s,d,e)
.matrix <- matrix(combn(x,3), ncol=3, byrow=T)
any_A <- apply(.matrix, 1, `%in%`, x = 'A')
as.list(as.numeric(any_A))
}
Never grow an object within a for loop, pre-allocate then fill.
Avoid naming objects with function names (eg c or matrix orlist)

Answer 2

You meant to test for "A" %in% matrix[i,], not the other way around. However, note that
row <- nrow(matrix)
list <- list()
for (i in seq(row)) {
if ("A" %in% matrix[i,]) {c(list, "1")}
else {c(list, "0")}
}
can be rewritten
rowSums(matrix == "A") > 0
It returns a vector of logicals (TRUE/FALSE) which is the most appropriate output for your function. However, if you really need a list of '1' or '0', you can wrap it as follows:
as.list(ifelse(rowSums(matrix == "A") > 0, "1", "0"))
Also note that it is a bad idea to name an object matrix since it is also the name of a function in R.