R ifelse with 2 dataframes

Question

consider 2 dataframes: p1 <- data.frame(x1 = c(5,8), y1=c(3,8)); p2 <- data.frame(x1 = c(2,10), y1=c(5,3))

I want to compare each value of p1 respectively to the value of p2 (same position), I tried:
ifelse( p1 < p2, p2 - p1, ifelse(p1 > p2, p1 + p2, 1))

I want have result: data.frame(x1 = c(7,2), y1=c(2,11))

but it seems ifelse work only on vectors and it returns a list.

do you have an idea?

score 3 · Accepted Answer · answered Aug 13 '20 at 10:23

3

If you convert p1 and p2 to matrices, your original ifelse() works:

p1 <- as.matrix(p1)
p2 <- as.matrix(p2)
p3 <- as.data.frame(ifelse( p1 < p2, p2 - p1, ifelse(p1 > p2, p1 + p2, 1)))
p3
  x1 y1
1  7  2
2  2 11

answered Aug 13 '20 at 10:23

Ben Norris

score 1 · Answer 2 · answered Aug 13 '20 at 10:16

1

You can try the code below

(p2-p1)*(p1<p2)+(p2+p1)*(p1>p2) + 1*(p1==p2)

or

p2 + p1*((p1>p2)-(p1<p2)) + 1*(p1==p2)

both of which will give

  x1 y1
1  7  2
2  2 11

answered Aug 13 '20 at 10:16

ThomasIsCoding

score 1 · Answer 3 · answered Aug 13 '20 at 10:22

Your attempt does not work because you are using ifelse on dataframe. You can convert your dataframe to matrix and it would work.

p1 <- as.matrix(p1)
p2 <- as.matrix(p2)
ifelse(p1 < p2, p2 - p1, ifelse(p1 > p2, p1 + p2, 1))

#     x1 y1
#[1,]  7  2
#[2,]  2 11

You can convert the above result to dataframe if needed.

3 Answers3