CODEWITHSUNDEEP
r
sedsiv
sedsiv

Reputation: 547

R weird {if-else} behaviour

I have the following if-else block and want to store its result in a variable.

x <- round(runif(100, -50, 50))
maxD <- 30
check1 <- T

y <- {
  if(x > 0 && !check1) pmax(pmin(x, maxD), 0) else if(x < 0 && check1) x else 0
}

Given that check1 == T, I'd expect y to be between -50 and 0, but the code doesn't seem to cut the values > 0. Why?

Also if I change check1 = F, then the output is a single value. But when I restart R and rerun the code (with check1 = F) I get a vector. When I change the value of check1 again and then again, I suddenly get a single value. It is also often different after I restart R. This seems kinda arbitrary. What's happening here?

Upvotes: 0

Views: 60

Answers (1)

TimTeaFan
TimTeaFan

Reputation: 18541

The problem is that x is a vector, but && does't work with vectors. It will only evaluate the first element.

c(TRUE, FALSE) && TRUE
[1] TRUE

Given further that you generate x randomily with runif you will get a different result every time you run this code.

Upvotes: 3

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