add sample option in order to deal with big number of files

[lecorguille]

origin: workflow4metabolomics/camera.archive#9

@yguitton - 13 Jun 2016

In Annotate Diffreport the argument sample=NA by default but sometimes the number of files is to high and groupCorr failed due to memory issues
it is possible to select some files only by settings sample=c(1,5,11...)

can we add that option as text filed in hidden option?
Thanks

@lecorguille - 22 Jul 2016

Do you imagine a threshold to determine a limit number of samples before process on a random selection among the samples sample=c(1,5,11...)?

@yguitton - 13 Jan 2017

hard to known in advance. I would suggest the use of a try( ...) then on error use sampling option.