[R] Warning: condition has length > 1

sosman
2005-10-09T05:30:42Z

nawaf b wrote:
> Hi -
>
> I was wondering if anyone came across a problem such as mine! I was trying
> to create a user-defined function, however, the results from calling the
> function are unexpected!
>
> When passing X parameter as a single value variable (x<-c(3)),
everything
> works fine. However, when passing a parameter as a vector with multiple
> values (as the case in my code), the 'if condition' is only
executed once!
>
> Here is my code:
>
>>x
>
> [1]  0.3  1.0  0.7 22.0
>
>>myfunction<-function(x)
>
> + {
> + if (x>=1) 0
> + else x^2
> + }
>
>>myfunction(x)
>
> [1]   0.09   1.00   0.49 484.00
> Warning message:
> the condition has length > 1 and only the first element will be used in:
if
> (x >= 1) 0 else x^2
>
>
> Is there a way to overcome this issue? Can you please explain what
> modifications to the code I need to accommodate to make it work.

I am going to go out on a limb here (I don't know much about R) but I'm
not sure it has anything to do with that fact that you have defined a
function.

It seems to me that "if (x > 1) {...}" expects a scalar and if x is
not
a scalar, it will use the first value.  To apply your function to each
element, check out the help for sapply (eg ?sapply).  I am guessing the
solution is something like sapply(x, myfunction) but don't quote me.

paul sorenson