A Panmat object contains a pan-matrix, which is the fundamental data structure
for pan-genome analyses. It is a small (S3) extension to a matrix. It has one row for each
genome in the study, and one column for each gene cluster. The number in cell [i,j] is the
number of sequences in genome i that belongs to cluster j. A Panmat object is
typically created by the function panMatrix.
The plot.Panmat function will display the content of the Panmat object as a bar
chart showing the number of clusters found in 1,2,...,G genomes, where G is the total number of genomes
in the study (rows in Panmat).
The summary.Panmat function will display a text giving the same information as
plot.Panmat.