mapByGroup: Draw a Map using Different Colored Symbols for Groups
In JVAdams/EchoNet2Fish: Estimate Fish Abundance from Acoustic Echoes and Net Catch

Draw a map using different colored symbols for different groups.

mapByGroup(
  bygroup,
  sug = sort(unique(bygroup)),
  addMean = TRUE,
  lon,
  lat,
  rlon = range(lon, na.rm = TRUE),
  rlat = range(lat, na.rm = TRUE),
  cushion = 0.1,
  colorz = NULL,
  pch = 1,
  cex = 1.5,
  mapcol = "gray",
  mar = c(0, 0, 2, 0)
)

`bygroup`	Vector, identifying the group membership of the locations to be mapped.
`sug`	Vector, identifying the unique groups to which locations may belong, default sort(unique(`bygroup`)).
`addMean`	Logical scalar indicating if group names should be added to plot at the mean location of each bygroup, default TRUE.
`lon`	A numeric vector of longitudes in decimal degrees.
`lat`	A numeric vector of latitudes in decimal degrees. Same length as `lon`.
`rlon`	A numeric vector of length 2, range of longitudes to map, in decimal degrees, default is the range of `lon`.
`rlat`	A numeric vector of length 2, range of latitudes to map, in decimal degrees, default is the range of `lat`.
`cushion`	A numeric scalar indicating the amount of cushion to add to the `rlon` and `rlat` ranges in decimal degrees, default 0.1.
`colorz`	A vector of colors to use, either of length 1 or the same length as `lon`. If NULL, the default, a range of colors will be assigned automatically.
`pch`	A vector of plotting characters or symbols, either of length 1 or the same length as `lon`, default 1. See `points`.
`cex`	A numeric vector giving the amount by which plotting characters and symbols should be scaled relative to the default, either of length 1 or the same length as `lon`, default 1.5.
`mapcol`	A scalar, the color used to draw the map lines (e.g., lake boundary), default "gray".
`mar`	A numeric vector of length 4, the number of lines of margin c(bottom, left, top, right) around the plotted map plot, default c(0, 0, 0, 0).

## Not run: 
 mygroup <- c(1, 1, 1, 2, 2, 2, 3, 3, 3)
 mylon <- -c(81.1, 81.2, 80.5, 83, 82.2, 82.7, 82.7, 82, 82.2)
 mylat <- c(45.7, 45.4, 45, 45.5, 45.4, 45, 44.4, 44.4, 43.9)
 mapByGroup(bygroup=mygroup, lon=mylon, lat=mylat, cushion=0.7)

## End(Not run)