What does this function mean?

Question

[Za]

Hi,

In URD R package for finding variable genes this function has been used

var.by.stage <- lapply(seq(3,12,3), function(n) {
  findVariableGenes(axial, cells.fit=cellsInCluster(axial, "stage", stages[(n-2):n]), set.object.var.genes=F, diffCV.cutoff=0.3, mean.min=.005, mean.max=100, main.use=paste0("Stages ", stages[n-2], " to ", stages[n]), do.plot=TRUE)
})

I know the tutorial data has 12 developmental stages, but in seq(3,12,3) I can not figure out what is 3? If I have 8 developmental stages, and I want to find variable genes between all of cells, how this function should be changed?

Thank you

https://github.com/farrellja/URD/blob/master/Analyses/QuickStart/URD-QuickStart-AxialMesoderm.Rmd

[WouterDeCoster]

In R, try: ?seq and read the documentation

[ATpoint]

Hint: keyword is by

[GenoMax]

I can not figure out what is 3?

@ATpoint has told you that above. 3, 6, 9, 12

seq    by number: increment of the sequence.