[FORGED] custom function gives unexpected result - for me

The answer is very simple:  parentheses.  (Also think about "operator 
precedence".) If you assign rn <- 3, then 1:rn-1 is:

[1] 0 1 2

The "-" operator is applied *after*  the ":" operator.

You want 1:(rn-1) which gives

[1] 1 2

and the desired result.

cheers,

Rolf Turner

On 18/04/20 7:55 am, Monica Palaseanu-Lovejoy wrote:

Hi,

I wrote a relatively simple function. If i run the code inside the

function

line by line i am getting the result i was expecting, but if i run

the

function, i get a different result.

The function:

grr1 <- function(rn) {
r.up <- c()
for (i in 1:rn-1) {
if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1)
r.up <- c(r.up, ru)
}
return(r.up)
}

So, if rn is 3 for example i would expect to get 1 1 2

grr1(3)
[1] 1 0 1 1 2

If i run it line by line inside the function:
r.up <- c()

r.up

NULL

i=1
if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1)

ru

[1] 1

r.up <- c(r.up, ru)
r.up
[1] 1

i=2
if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1)
ru
[1] 1 2
r.up <- c(r.up, ru)

r.up

[1] 1 1 2

So - i am getting the result i am expecting. From where the 1 0

before what

i expect as a result comes from? I am sure i am doing some very basic
error, but it seems i cannot figure it out.

I run R x64  3.2.6. I know it is not the latest version, but it

should not

give me unexpected results because of that i would think.

sessionInfo()
R version 3.6.2 (2019-12-12)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] compiler_3.6.2

Thanks,
Monica