I tried "GWASTools" R package, and I would be happy if you help me out of a problem.

When I tried 'gdsSubset' function, an error occurred with the following message;

 "gds nodegenotypemust have 'snp.order' or 'sample.order' as an attribute".

My question is how to put  'snp.order' or 'sample.order' attribute to a 'gds' substance. 

The following is the sample code I am using.

library(gdsfmt)

# construct gds file and put data

gfile<-createfn.gds("test.gds")

gen_node<-add.gdsn(gfile, "genotype", storage="bit2", valdim=c(20, 10)) #20 snps, 10 scans=samples

add.gdsn(gfile, "snp.id", val=c(1:20))

add.gdsn(gfile, "sample.id", val=c(1:10))

add.gdsn(gfile, "snp.chromosome", val=c(1:20))

add.gdsn(gfile, "snp.position", val=c(1:20)*100)

write.gdsn(gen_node, matrix(rep(c(0:3),50), nrow=20), start=c(1,1), count=(c(20,10)))

closefn.gds(gfile)

# read gds file and subset the file

library(GWASTools)

gds <- GdsGenotypeReader("test.gds", "snp,scan")

sub.file<- tempfile()

close(gds)

gdsSubset("test.gds", sub.file, sample.include=c(1:5))

# HERE! error occures! saying...

#Error in gdsSubset("test.gds", sub.file, sample.include = c(1:5)) :

 #gds nodegenotypemust have 'snp.order' or 'sample.order' as an attribute

You can use put.attr.gdsn to define the genotype node as "snp.order" (snp x sample) or "sample.order" (sample x snp).

library(gdsfmt)
gfile <- createfn.gds("test.gds")
gen_node <- add.gdsn(gfile, "genotype", storage="bit2", valdim=c(20, 10)) #20 snps, 10 scans=samples
put.attr.gdsn(gen_node, "snp.order")
add.gdsn(gfile, "snp.id", val=c(1:20))
add.gdsn(gfile, "sample.id", val=c(1:10))
add.gdsn(gfile, "snp.chromosome", val=c(1:20))
add.gdsn(gfile, "snp.position", val=c(1:20)*100)
write.gdsn(gen_node, matrix(rep(c(0:3),50), nrow=20), start=c(1,1), count=(c(20,10)))
closefn.gds(gfile)

library(GWASTools)
(gds <- GdsGenotypeReader("test.gds"))
close(gds)

sub.file <- tempfile()
gdsSubset("test.gds", sub.file, sample.include=c(1:5))
(gds <- GdsGenotypeReader(sub.file))
close(gds)
unlink(c(sub.file, "test.gds"))

Thanks!

It worked!