Plot point pattern (list)
# S3 method for ppplist
plot(x, ..., frame = 1, main = "ppp", combined = TRUE)
input
arguments passed on to the function
the element number of the list object (by default, 1)
title
logical. `combined` specifies whether to combine all the point processes to one plot. This argument applies only to the case when users specify one column with multiple time periods. By default = TRUE