[R] really dumb question | loop counters in

[Evan Cooch]

Duncan Murdoch wrote:
> On 21/09/2007 6:54 PM, Evan Cooch wrote:
>> Thanks, but  there is nothing in section 9.2.2 that mentions 
>> seq(x,y,z) or anything close in a for loop.  All it says is (basically):
>>
>>
>> There is also a for loop construction which has the form
>>  > for (name in expr_1) expr_2
>> where name is the loop variable. expr 1 is a vector expression, 
>> (often a sequence like 1:20), and
>> expr 2 is often a grouped expression with its sub-expressions written 
>> in terms of the dummy
>> name. expr 2 is repeatedly evaluated as name ranges through the 
>> values in the vector result of
>> expr 1.
>>
>> Moreover, I would have assumed it would be in the language definition 
>> file (not that I could find - I did check),
>
> You seem to be assuming the language is different than it is.  To do 
> the loop you want, you construct the vector of values you want to loop 
> over, and loop over it.  There's no specific syntax for that, because 
> there's no need for it.  There's just a for loop that loops over a 
> general vector.  You can put anything you want in that vector.
>
>
Point being, the documentation makes the implicit assumption that the 
new user will immediately recognize that the argument is a vector, and 
how to specify the sequence over the vector. This is a good example of 
what I call obtuse documentation (having written ~1100 pages of 
documentation for various opensource programs, I'm sort of sensitive to 
this).

Regardless, thanks for your help.