filtering large vcf. GQ and DP

hi everyone, i’m new in bioinformatics, i have a big VCF file, i get dp from there using
dp = extract.gt (vcf, element=”DP”, as.numeric = TRUE)
dpp = apply (dp, 2, sum)
and I build a plot
barplot (sort (dpp), las = 3, main = “DP”, col = 1:12), I need to take averages from this graph and do a GQ analysis on them, how can I do that?