 test<-by(vol,x, vol.exp)
Error in tapply(1L:45L, list(DBH = 80:200), function (x)  :
  arguments must have same length

*Ben *


On Sat, Jul 30, 2011 at 10:16 AM, Benjamin Caldwell <btcaldwell@berkeley.edu
> wrote:

> Or maybe that function should look more like
>
> vol.exp<-function(x) {
> V<-((coefficient1*(x)^exponent1)+(coefficient2*(x)^exponent2)+constant)
> V
> }
>
> ?
> *Ben *
>
>
>
> On Sat, Jul 30, 2011 at 10:06 AM, Benjamin Caldwell <
> btcaldwell@berkeley.edu> wrote:
>
>> Hello,
>>
>> I'm just trying to wrap my head around the syntax for creating loops,
>> functions in R. I have an array of values from a .csv. Looks something like
>>
>> header<-c(species,coefficient1, exponent1, coefficient2, exponent2,
>> constant)
>>
>> with a species name for the first column, and values for coefficient1,
>> exponent1, coefficient2, exponent2, constant for each species.
>>
>> The values are parameters for an equation
>>
>> V<-((coefficient1*(x)^exponent1)+(coefficient2*(x)^exponent2)+constant)
>>
>> x<1:100
>>
>> I'd like to run the equation using the parameters for each species and the
>> vector x to simulate what V would be for the range of values x, and then
>> plot a graph of for each species.
>>
>> Would the way to do this be some sort of apply nested within a for loop?
>> Code so far looks like
>>
>> vol<-read.csv("frame.csv")
>>
>> vol.exp<-function(coefficient1, exponent1, coefficient2, exponent2,
>> constant,x) {
>> V<-((coefficient1*(x)^exponent1)+(coefficient2*(x)^exponent2)+constant)
>> V
>> }
>> x<1:100
>>
>> Thanks
>>
>> *Ben *
>>
>>
>

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