[R] How to write string dynamicly?

[Feng Qiu]

Hi Gabor:
          Thank you!  But it didn't work. Since lda() takes the variable 
name as the input parameter. So what I was trying to do is "make the name 
dynamically". I used sprintf() to generate a variable name, such as "V16". 
But it seems that the function doesn't recognize the generated name. For 
example, lda(V16,data=mydata) works, But,
lda(sprintf("V%d",k),data=mydata) does not work, where k=16.  So I guess the 
name generated by sprintf is not the parameter wanted. But I have no idea 
about it.

Best,

Feng


----- Original Message ----- 
From: "Gabor Grothendieck" <ggrothendieck at gmail.com>
To: "Feng Qiu" <fqiu at gatech.edu>
Cc: <r-help at stat.math.ethz.ch>
Sent: Wednesday, December 27, 2006 1:56 PM
Subject: Re: [R] How to write string dynamicly?


> Try:
>
> lda(iris[-5], iris[,5])
>
> On 12/26/06, Feng Qiu <fqiu at gatech.edu> wrote:
>> Hi everyone:
>>         I'm trying to compose a string dynamicly for the parameter input 
>> of
>> some function. For example:
>> In package MASS, function lda() require to input the name of predictor
>> variable. Let's say the 16th column is the predictor variable. Then we 
>> call
>> the function like this: lda(V16~., data=mydata). I don't want to 
>> hard-code
>> the call, instead, I would like to use a dynamic expression for this
>> parameter so that I can use my program on different set of data.
>>        I guess there,- are some function that can do this, but I didn't 
>> find
>> it in "Introduction to R" so far, could someone please tell me this kind 
>> of
>> function? Thank you!
>>
>> Best,
>>
>> Feng
>>
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>>
>