ifelse is acting oddly by giving answer other than designed, in r

Asked Apr 28 '20 at 07:06

Active Apr 28 '20 at 07:06

Viewed 22 times

I am trying to make a random sequence with sample when condition is TRUE. But it gives a sigle element, instead of whole sequence.

A <- 2
B <- 3
Condition <- TRUE

# all 6 elements are printed randomly.
print(sample(A*B, A*B))

# all 6 elements are printed in order.
print(1:(A*B))

Q <- ifelse(TRUE, sample(A*B, A*B), 1:(A*B))

# only ONE element is printed.
print(Q)

interestingly the ifelse gives the unexpected result (as attached) . Please advise.

I am with MRO 3.5.3 on ubuntu 1804

asked Apr 28 '20 at 07:06

Grec001

1,111
6
20

1

https://stackoverflow.com/questions/27778559/why-does-ifelse-return-single-value-output – JDG Apr 28 '20 at 07:08
3

`ifelse` returns a vector the length of its first argument, so if you use `ifelse(TRUE, x, y)` it will also return the first element of x. – David Apr 28 '20 at 07:08
2

For scalar inputs use `if`/`else`. `ifelse` is for vectors. `if(TRUE) sample(A*B, A*B) else 1:(A*B)` – Ronak Shah Apr 28 '20 at 07:12
1

thanks JDG and David. It helps a lot. – Grec001 Apr 28 '20 at 07:12

ifelse is acting oddly by giving answer other than designed, in r

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