Placing labels in the plot

Question

[akang]

Hi all! I made an admixture plot and now i want to place the population names along the x-axis of the plot. I want to place the labels in he centre of the number of samples that belong to a particular population. If I have 5 populations with sample size 10, 20,20,35,100 then label should be at 10/2 for population 1, 20/2 for population 2 and so on. I tried the following but it doesnt work. Ill appreciate any further help!

pop<-c("pop1", "pop2", "pop3", "pop4", "pop5")
n<-c(10, 20,20,35,100)
at <- n/2
barplot(t(as.matrix(tbl)),col=rainbow(5),width=1,space=1)
mtext(1,at=at,text=pop,cex=1, las=2)
for{....
}

[natasha.sernova]

See this post, it may help

ADMIXTURE and R, color meaning on barplot in studing population ancestry, K value

See also this link:

https://github.com/mkanai/cancritls/blob/master/admixture/admixture.plot.r

The guide looks useful too:

https://cran.r-project.org/web/packages/admixturegraph/vignettes/admixturegraph.html

Or these examples:

http://www.statmethods.net/advgraphs/axes.html

[akang]

Thank's Natasha! In my case all what i am looking for is to place my labels with respect to my populations and their sample size..

[WouterDeCoster]

Could you show us what you have and what you would like to have? An example?

[akang]

I have a plot like this(without the labels on X-axis)..http://journals.plos.org/plosgenetics/article/figure/image?size=medium&id=info:doi/10.1371/journal.pgen.1004254.g006 To a barplot like this i want to add population labels(Like how you see in the plot). For plotting without population labels i did this but i dont know how to put population labels. Each row corresponds to each sample in the population. There are ~500 total samples belonging to 5 different populations. Each population has different number of samples. Example Input file is like below

test.5.Q
0.364957    0.00001 1.00E-05    0.00001 1.00E-05
0.485423    0.017426    1.00E-05    0.00001 1.00E-05
0.399289    0.00001 1.00E-05    0.002894    1.00E-05
0.579652    0.00001 1.00E-05    0.00001 1.00E-05
0.578574    0.00001 1.00E-05    0.00001 1.00E-05
0.597478    0.00001 1.00E-05    0.00001 1.00E-05
> tbl=read.table("test.5.Q")
> barplot(t(as.matrix(tbl)), col=rainbow(3),xlab="Individual #", ylab="Ancestry", border=NA)