How to use values from previous row and column
I am trying to create a new variable that is a function of the previous rows and columns. I found the lag () function in dplyr, but it cannot accomplish exactly what I would like.
library(dplyr)
x = data.frame(replicate(2, sample(1:3,10,rep=TRUE)))
X1 X2
1 1 3
2 2 3
3 2 2
4 1 3
5 2 3
6 2 1
7 3 2
8 1 1
9 1 3
10 2 2
x = mutate(x, new_col = # if x2==1, then the value of x1 in the previous row,
# if x2!=1, then 0))
My best attempt:
foo = function(x){
if (x==1){
return(lag(X1))
}else{
return(0)
}
x = mutate(x, new_col=foo(X1))
+3
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2 answers