Re: [R] for loop help

From: Hans-Jörg Bibiko <bibiko_at_eva.mpg.de>
Date: Fri, 11 Apr 2008 07:57:13 +0200

On 11.04.2008, at 05:38, <Bill.Venables_at_csiro.au> <Bill.Venables_at_csiro.au> wrote:

>> ?`break`
>> ?`next`
>>
>
>
>> for(i in 1:13) {
>>
> if(i < 13) next
> print("Hello!\n")
> }
> [1] "Hello!\n"
>
>>
>>
>
> I am trying to find a solution in R for the following C++ code that
> allows
> one to skip ahead in the loop:
>
> for (x = 0; x <= 13; x++){
> x=12;
> cout << "Hello World";
> }
>
> Note that "Hello World" was printed only twice using this C++ loop. I
> tried to do the same in R:
>
> for(i in 1:13){
> i=12
> print("Hello World")
> }
> It doesn't work as I expected, i.e., this R loop prints "Hello
> World" 13
> times.
>

Maybe to understand this try:
for(i in 1:13){i <- rnorm(1);print(i)}

You cannot change the seq in a for loop as you can in C, Perl, etc. The variables i in for() and the i within the statement are not the same. Thus you only can query i (see Bill's hint).

see also ?Control; last paragraph in 'Details'

--Hans



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