if(requireNamespace("ggplot2")){
library(ggplot2)
ggplot(o2cons, aes(x=Group, y=O2)) + geom_point(alpha=0.5) + facet_grid(Staphylococci~Time) +
stat_summary(fun.y = mean, fun.ymin = min, fun.ymax = max, colour = "red")
}
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