有类似x的方法吗？ y：R中的z？

Question

With

df <- data.frame(v1=c(1:5), v2=c(9,32,6,17,11))

I need to add a new column v3 with value 1 or 0 based on whether values in v2 are larger than 10 or not so that:

df
  v1 v2 v3
1  1  9  0
2  2 32  1
3  3  6  0
4  4 17  1
5  5 11  1

Is there such thing like x ? y : z in R? If not, what's a good way to solve the above? Thanks!

Answer 1

ifelse(..) comes closest:

R> df <- data.frame(v1=c(1:5), v2=c(9,32,6,17,11))
R> df$v3 <- ifelse(df$v2 > 10, 1, 0)
R> df
  v1 v2 v3
1  1  9  0
2  2 32  1
3  3  6  0
4  4 17  1
5  5 11  1
R> 

Answer 2

I don't know whether ifelse is faster, but this is easier to read:

> d <- data.frame(v1=c(1:5), v2=c(9,32,6,17,11))
> d$v3 <- as.numeric(d$v2 > 10)
> d
  v1 v2 v3
1  1  9  0
2  2 32  1
3  3  6  0
4  4 17  1
5  5 11  1