Calculate GC content of the whole sequences.
Examples
# estimate GC content of yeast genes
cf_all <- count_codons(yeast_cds)
gc <- get_gc(cf_all)
head(gc)
#> YPL071C YLL050C YMR172W YOR185C YLL032C YBR225W
#> 0.3566879 0.3981481 0.4101852 0.4027149 0.3454399 0.3880873
hist(gc)