在ggplot2中的分组散点图中为每个组添加任意标签

I have a list of matrices I wish to plot. Each element in the list ultimately represents a facet to be plotted. Each matrix element has dimensions Row * Col, where all values in a row are grouped and plotted as a scatterplot (i.e. X-axis is categorical for the row names, Y-axis is the value, Col. values per row).I have a list of matrices I wish to plot. Each