# [R] QQ plot

Ana Marija @okov|c@@n@m@r|j@ @end|ng |rom gm@||@com
Tue Aug 13 21:47:31 CEST 2019

```Hello,

I was plotting QQ plot (in attach) via:

qqunif = function(p, BH=T, MAIN = " ", SUB=" ")
{
nn = length(p)
xx =  -log10((1:nn)/(nn+1))
plot( xx,  -sort(log10(p)),
main = MAIN, sub= SUB, cex.sub=1.3,
xlab=expression(Expected~~-log(italic(p))),
ylab=expression(Observed~~-log(italic(p))),
cex.lab=1.0,mgp=c(2,1,0))
abline(0,1,col='red')
if(BH) ## BH = include Benjamini Hochberg FDR
{

abline(-log10(0.05),1, col='black',lty=1)
text(0.5,1.9 , "FDR=0.05", col = "gray60",srt=45, cex=1)
abline(-log10(0.10),1, col='black',lty=1)
text(0.5, 1.6, "FDR=0.10", col = "gray60",srt=45, cex=1)
abline(-log10(0.25),1, col='black',lty=1)
text(0.5, 1.2, "FDR=0.25", col = "gray60",srt=45, cex=1)
#legend('topleft', c("FDR = 0.05","FDR = 0.10","FDR = 0.25"),
#col=c('black','black','black'),lty=c(1,1,1), cex=0.8)
if (BF)
{
abline(h=-log10(0.05/nn), col='black') ## bonferroni
}
}
}

dd=db[db\$P<1e-3,]
qqunif(dd\$P)

what do I need to change in my code so that FDR lines look like on the
2nd attachment?

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