Convert continuous dataframe into binary dataframe in R - r

Question

I have the following data frame:
i39<-c(5,3,5,4,4,3)
i38<-c(5,3,5,3,4,1)
i37<-c(5,3,5,3,4,3)
i36<-c(5,4,5,5,4,2)
ndat1<-as.data.frame(cbind(i39,i38,i37,i36))
> ndat1
i39 i38 i37 i36
1 5 5 5 5
2 3 3 3 4
3 5 5 5 5
4 4 3 3 5
5 4 4 4 4
6 3 1 3 2
My goal is to convert any value that is a 4 or a 5 into a 1, and anything else into a 0 to yield the following:
> ndat1
i39 i38 i37 i36
1 1 1 1 1
2 0 0 0 1
3 1 1 1 1
4 1 0 0 1
5 1 1 1 1
6 0 0 0 0

Answer 1

With your data set I would just do
ndat1[] <- +(ndat1 >= 4)
# i39 i38 i37 i36
# 1 1 1 1 1
# 2 0 0 0 1
# 3 1 1 1 1
# 4 1 0 0 1
# 5 1 1 1 1
# 6 0 0 0 0
Though a more general solution will be
ndat1[] <- +(ndat1 == 4 | ndat1 == 5)
# i39 i38 i37 i36
# 1 1 1 1 1
# 2 0 0 0 1
# 3 1 1 1 1
# 4 1 0 0 1
# 5 1 1 1 1
# 6 0 0 0 0
Some data.table alternative
library(data.table)
setDT(ndat1)[, names(ndat1) := lapply(.SD, function(x) +(x %in% 4:5))]
And I'll to the dplyr guys have fun with mutate_each

Answer 2

I used the following to solve this issue:
recode<-function(ndat1){
ifelse((as.data.frame(ndat1)==4|as.data.frame(ndat1)==5),1,0)
}
sum_dc1<-as.data.frame(sapply(as.data.frame(ndat1),recode),drop=FALSE)
> sum_dc1
i39 i38 i37 i36
1 1 1 1 1
2 0 0 0 1
3 1 1 1 1
4 1 0 0 1
5 1 1 1 1
6 0 0 0 0
I was just wondering if anyone else had any thoughts, but overall I am satisfied with this way of solving the issue. Thank you.