[MINC-users] calculating r-squared values

[Jared Rowley]

Hi Jason,

Thanks for the response.

I did the following and got an error do you have any suggestions:

rm(list=ls(all=TRUE))
> library(RMINC)
> gf1 <- read.csv("dti_gd.csv")
> fff <- function(x) { return(summary(lm(FA ~ score, gf1))$r.squared) }
> mincApply(gf1$FA, quote(fff(x)))
Number of volumes: 91
Volume sizes: 193 229 193
In slice
 0 Error in storage.mode(y) <- "double" :
  invalid to change the storage mode of a factor
In addition: Warning message:
In model.response(mf, "numeric") :
  using type="numeric" with a factor response will be ignored

FA is a column of minc files and score is a column of integers I want to
correlate with FA.

Thanks very much,

Jared


On Wed, Jun 6, 2012 at 1:35 PM, Jason Lerch <jason at phenogenomics.ca> wrote:

> This should work, though is going to be slow:
>
> fff <- function(x) { return(summary(lm(x ~ genotype, gf))$r.squared) }
>
> mincApply(filenames, quote(fff(x)))
>
> Note: replace the formula in that function with the appropriate formula
> for your purposes, and filenames should be a vector of your filenames.
> Could be worth specifying a mask, as this will run for a few hours.
>
> And I haven't actually tested it, so it might not run at all!
>
> Jason
>
> On 2012-06-05, at 4:18 PM, Jared Rowley wrote:
>
> > Hi Minc Users,
> >
> > I was wondering if anyone knows a way calculate R-squared values on a
> voxel
> > level from a linear regression.
> >
> > I assume there is a way with either glim_image or RMINC however reading
> > though the documentation I could not find a solution.
> >
> > Thanks very much,
> >
> > Jared
> > _______________________________________________
> > MINC-users at bic.mni.mcgill.ca
> > http://www.bic.mni.mcgill.ca/mailman/listinfo/minc-users
>
> _______________________________________________
> MINC-users at bic.mni.mcgill.ca
> http://www.bic.mni.mcgill.ca/mailman/listinfo/minc-users
>



-- 
Jared Rowley
Translational Neuroimaging Laboratory
McGill Centre for Studies in Aging
Douglas Hospital Research Center
McGill University
6825 LaSalle Blvd.
Montreal, QC Canada
H4H 1R3