在 R 中编写 if / ifelse 函数

Question

I am attempting to write a function in order to create a variable (BBDR) based on the conditions of another variable (Site0) using the if function. I have the following code using the if function.

x1 <- (africanaDamRate$BB6-africanaDamRate$BB0)/29
x2 <- (africanaDamRate$BB6-africanaDamRate$BB0)/22
x3 <- (africanaDamRate$BB6-africanaDamRate$BB0)/34
x4 <- (africanaDamRate$BB6-africanaDamRate$BB0)/30


F1 <- function(y){
if(africanaDamRate$Site0==1){africanaDamRate$BBDR<-x1}
if(africanaDamRate$Site0==2){africanaDamRate$BBDR<-x2}
if(africanaDamRate$Site0==3){africanaDamRate$BBDR<-x3}
if(africanaDamRate$Site0==4){africanaDamRate$BBDR<-x4}
}


africanaDamRate$BBDR<-F1(y)

But when I attempt this code I receive "The condition has length greater than 1..."

I have also attempted using the ifelse function with the following code:

africanaDamRate$BBDR<-ifelse(c(africanaDamRate$Site0==1, x1, NA), c(africanaDamRate$Site0==2, x2, NA), c(africanaDamRate$Site0==3, x3, NA), c(africanaDamRate$Site0==4, x4, NA))

But get the "unused argument" error.

Does anyone have any ideas of how I can do this (without subsetting)? Thanks so much!

Ryan

Answer 1

Your ifelse statement is wrong. It could be written like this:

africanaDamRate$BBDR <- ifelse(africanaDamRate$Site0 == 1, x1, 
                               ifelse(africanaDamRate$Site0 == 2, x2, 
                                      ifelse(africanaDamRate$Site0 == 3, x3, 
                                             ifelse(africanaDamRate$Site0 == 4, x4, NA))))