for loop and if else in R

df_test2<-data.frame(test1=c("in","out"),
                     test2=c(1:2))

> df_test2
  test1 test2
1    in     1
2   out     2

for (i in df_test2$test1){
  for (j in df_test2$test2){
    if(i="in"){
      print(j+1)
    }else{
      print(j-1)
    }
  }

I ran the above code and nothing returned while I was expecting see the outcome being 2 and 1. Mind telling if I am using the wrong loop technique? Many thanks.

>Solution :

I would do it without a for loop

> with(df_test2, ifelse(test1 == "in", test2+1, test2-1))
[1] 2 1

Note that = is an assignment operator equivalent to <- and you want to do a logical comparison, so you should use == instead.

If you want for whatever reasong a for loop, then you can write it using just one index for selecting rows:

for (i in seq_len(nrow(df_test2))){
  if(df_test2[i, 1] == "in"){
    print(df_test2[i, 2] + 1)
  } else {
    print(df_test2[i, 2] - 1)
  }
}