dd_plot_all: dd_plot_all
In mpadge/distdecay: Calculate Distance Decay Functions

Plot distance decay functions for all cities

1	dd_plot_all(from = TRUE, mi = FALSE, smoother = FALSE)

`from`	Plot covariance or MI values for trips from each station. If `FALSE`, plot equivalent values for trips to each station.
`mi`	If `TRUE`, plot decay functions for mutual information, otherwise plot covariances.
`smoother`	if `TRUE`, overlay a loess-smoothed line. (This will generally take much longer to plot.)