Convert all variables into ordered factors - r

Question

I am using the semTools package to carry out EFA using categorical data. The efaUnrotate() function requires variables as ordered factors.
I am trying to convert all of my already factor variables into an ordered one using a simple code, which does not seem to work unfortunately. I wonder if anyone had an explanation for this?
My data:
test <- structure(list(fp_weightloss = structure(c(1L, 1L, 1L, 1L, 1L,
1L), .Label = c("0", "1"), class = "factor"), fp_gripstrength = structure(c(1L,
2L, 1L, 1L, 1L, 1L), .Label = c("0", "1"), class = "factor"),
fp_walktime = structure(c(2L, 1L, 2L, 2L, 1L, 1L), .Label = c("0",
"1"), class = "factor"), fp_metmins = structure(c(2L, 1L,
1L, 1L, 2L, 1L), .Label = c("0", "1"), class = "factor")), class = c("tbl_df",
"tbl", "data.frame"), row.names = c(NA, -6L))
My code:
test_ord <- as.data.frame(sapply(test, as.ordered))
sapply(test_ord, class)
Results in no change:
fp_weightloss fp_gripstrength fp_walktime fp_metmins
"factor" "factor" "factor" "factor"
When I would expect:
class(as.ordered(test$fp_weightloss))
[1] "ordered" "factor"

Answer 1

The problem is sapply: best avoid it entirely, since its implicit conversions often invisibly mess with data, and they do here. Use lapply instead:
test_ord <- as.data.frame(lapply(test, as.ordered))
In general I prefer using vapply since it handles non-list return values, but getting vapply to work with S3 classes doesn’t seem possible.