force.chr.pos: Force a valid genomic range, given the inputted coordinates
In humarray: Simplify Analysis and Annotation of Human Microarray Datasets

Enter a pair of genomic locations representing a range for a given chromosome and this function will ensure that no position is less than 1 or greater than the relevant chromosome lengths. Anything below will be coerced to 1, and anything above to the chromosome length.

1	force.chr.pos(Pos, Chr, snp.info = NULL, build = NULL, dir = NULL)

`Pos`	must be numeric, length 2, e.g, c(20321,30123)
`Chr`	chromosome label
`snp.info`	optional object to take boundaries from, the maxima and minima for each chromosome within this object will take the place of the chromsome lengths / 1.
`build`	ucsc build, only need to enter if this differs from getOption("ucsc")
`dir`	directory to use for download of chromosome lengths (only if you wish to keep the chromosome length file)

pss <- ps <- c(345035,345035); ch <- 1
force.chr.pos(ps,ch)
pss[1] <- 0
force.chr.pos(pss,ch) # won't allow zero
pss[1] <- -1
force.chr.pos(pss,ch) # won't allow negative
pss[1] <- 645035012
force.chr.pos(pss,ch) # won't allow pos > chromosome length