PlotPopPyramid is mainly intended for companion animals population pyramids, although it can display other types of opposed bar charts with suitable modification of the arguments.The bars to the left of 0 on the x axis correspond to the minimum value of as.numeric (dat[, sex.col]). If str.col is not NULL, bars will be stacked, with the minimum value of as.numeric(dat[, str.col]) as their base.
On the top of the plot, it is displayed the total number of observations of each level of dat[, sex.col]. The levels of sex.col are used as labels.
The legend labels are equal to the levels of dat[, str.col].
Font size of saved plots is usually different to the font size seen in graphic browsers. Before changing font sizes, see the final result in saved (or preview) plots.
Other details of the plot can be modifyed using appropriate functions from ggplot2 package (see examples).