I am new to OmicCircos. In the first example of OmicCircos vignette, there is a code:

circos(R=240, cir=db, W=40, mapping=seg.v , col.v=19, type="ml", B=FALSE, col=colors, lwd=2, scale=TRUE).

I want to know how this code can show information of multiple samples? The parameter col.v only select the 19th column which corresponds to one sample information. 

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