pass by reference

Hi Jim, R,

What you just showed me simply prints out the 2nd column. If you inspect
your original data, it still just has 1 column. So its still passing by
value.

Thanks,
Sachin

On Tue, Aug 14, 2012 at 11:19 AM, jim holtman <jholtman at gmail.com> wrote:

You have to return the value of 'data' from the function.  Functions
do not have "side effects".

data<-data.frame(col1=c(1,2,3,4,5))

getcol2<-function(data){

+     data$col2[data$col1<=2]="L"
+     data  # return value
+ }

getcol2(data)

 col1 col2
1    1    L
2    2    L
3    3 <NA>
4    4 <NA>
5    5 <NA>

On Mon, Aug 13, 2012 at 9:08 PM, Sachinthaka Abeywardana
<sachin.abeywardana at gmail.com> wrote:

Hi all,

I want to do the following:

data<-data.frame(col1=c(1,2,3,4,5))

getcol2<-function(data){
   data$col2[data$col1<=2]="L"
}

getcol2(data)

Unfortunately in the above col2 does not appear in the final data. So how
would you pass this by reference such that you would get it back?

Thanks,
Sachin

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