[R] For Loop Help

Duncan Murdoch murdoch.duncan at gmail.com
Sun Jan 5 22:24:52 CET 2014

On 14-01-05 3:47 PM, Mathew Nagendran wrote:
> I'm relatively new to R. I'm trying to for loop but I keep getting an error message. Can anyone hint at what I am doing wrong please?

Nothing to do with the for loop.  You have a call to your t function in 
which you don't specify a value for the a argument.

BTW, t() is a standard R function to transpose a matrix; it's not a good 
idea to use that as your own function name, because you'll end up 
confused later.  It's better to use longer, more meaningful names.  And 
if you'd done this for the arguments to your function it might have been 
more obvious what the error message was talking about.

Duncan Murdoch

>> m.control=c(1.45,9.40,9.96,4.2,1.86,0.2)
>> m.sham=c(3.39,23.94,23.62,10.08,2.99,1.09)
>> t=function(m, a){(1-exp(-a*m))} #t function defined
>> d=function(ts, tc){(ts-tc)/ts} #d function defined
>> pick.a=seq(0.01,2,by=0.01) #set of a values defined
>> output=cbind(pick.a,d=rep(NA,length(pick.a))) #define array containing a values in column 1 and d values (outputs) in column 2
>> for(count in 1:length(pick.a)){
> + ts=sum(t(m.sham),pick.a[count])
> + tc=sum(t(m.control),pick.a[count])
> + output[count,2]=(ts-tc)/ts
> + }
> Error in -a : 'a' is missing
> 	[[alternative HTML version deleted]]
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