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maps

###R package for geographical maps

This is version 3 of the maps package. The main change with respectto v2 is a more recent world map. The old map legacy map is stillavailable from the package mapdata.

##CHANGES

• The ‘world’ data base has been replaced by a much more recent database, imported from the Natural Earth data project (the 1:50m world map,version 2.0, the latest version available in 2015) This may have severalimplications for code that calls map().
  • As of version 3.1, the ‘world’ database no longer contains lakes andlake islands. These are now in a separate database called ‘lakes’.
  • Country names have changed. This is inevitable, since e.g. post-1990Europe is dramatically different. As a consequence, any call to map()that involves the argument “region=…”, may be affected. For instance,map(‘world’,‘USSR’) is now obsolete, while map(‘world’,‘Russia’) worksfine.
  • The new data base contains less small islands, but the choice may bea bit different.
  • Some remote islands that are officially part of other countries maycause an unexpected change in the scale of a map. This is not a newphenomenon (map(‘world’,‘france’) had this in the old set), but some newcases may occur now. As explained below, this will now occurlessoften.
  • The naming of all polygons is as close as possible to the old worldmap. However, some inconsistencies have been remedied, e.g. on whetheran island is called by its own name or as part of the country it belongsto. The choice is now mainly dependent on whether the entity has aseperate ISO code. The naming scheme unfortunately does not permit torepresent all the intricacies. The data set iso3166 (see further) isadded to provide more details.
  • Because of this segmentation by ISO code (and, often parallel, byadmin-0 level), some countries now have much less islands. For instance,map(region=“France”) now only shows metropolitan France and one or tworemote islands. To add all overseas territories and departments, you canuse region=sov.expand(“France”), which creates a list of all countriesunder French sovereignty.
  • The new ‘world’ database has a higher resolution than before andlooks much smoother. In fact, for some applications it may now sufficerather than needing to import worldHires.
• Most functions now use perl-style regular expressions internally,rather than the default style. This gives more flexibility.

##ADDITIONS

• v3.1 includes support for ‘SpatialPolygons’ and ‘SpatialLines’classes. Such objects can now either be passed to map() directly orfirst be converted to a map-type list with the new functions‘SpatialPolygons2map()’ and ‘SpatialLines2map’. These functions do notcopy all the information present in the original data: only polygonnames and co-ordinates are preserved (additional information like holes,plotting order etc. is ignored).

• A new databse ‘lakes’ has been added. The standard ‘world’ map nolonger contains any lakes.

• A data frame iso3166 has been added which, for every country onthe new world map, lists the official name, the ISO3166 2- and 3-lettercodes, and also the sovereignty. Type ‘?iso3166’ for details.

• A set of simple functions use this iso3166 table for creating alist of countries to map. So you can use the 2- or 3-letter ISO code(e.g. as country labels on a map), but also create a list based on thesovereignty. Type ‘?iso.expand’ for details.

• v3.2 adds new options to map() for wrapping and exact boundaryclipping.

• v3.4.3 adds initial support for ‘sf’ class maps.

##FIXES - As of v3.2, maps::map() also works if the maps package isnot attached. You can even do maps::map(“madata::worldHires”). - As ofv3.1, map(…, fill=TRUE) no longer applies thinning. This removes smallartefacts, but plotting worldHires becomes rather slow, should you everwant to plot a full world map at such a high resolution. - map.text(…,exact=TRUE) now behaves as documented. Previously, the “exact=TRUE” wasnot passed to the map drawing if add=FALSE. To get the old(non-documented) behaviour (plot map with exact=FALSE, write text forexact=TRUE) you should now use 2 commands: * > map(…, exact=FALSE) *> map.text(…, exact=TRUE, add=TRUE) - match.map now works correctlyfor regions containing “:”. This was potentially broken due tolocale-dependent behaviour of order(). - ‘world2’ now has cleanboundaries when ‘fill=TRUE’.

##FALL BACK TO LEGACY WORLD DATABASE The old map data set has beenmoved to the ‘mapdata’ package, where it is called “worldLores”. It canthus be called via map(“mapdata::worldLores”).

Note that the worldHires database from the mapdata package hasidentical map naming than the legacy world map. The only difference isin the resolution of the polylines. That high resolution version of thelegacy map will remain unchanged.

Please inform the maintainer of any problem that requires a fallbackto the legacy database!

HIGH RESOLUTION AND OTHERMAPS

Natural Earth also supports a high-resolution (1:10m) world map.Rather than replacing ‘worldHires’ (in the mapdata package), this dataset can be imported into maps e.g. by loading the “rnaturalearth”package.

Even maps in e.g. shapefile format can now easily be imported for usein ‘map()’. For instance the package ‘maptools’ offers the function‘readShapePoly()’, which reads a shapefile into a‘SpatialPolygonsDataFrame’ that can be used as a map database (as ofversion 3.1).

##TO DO/DISCUSS: - The old naming convention is largely maintained,but some choices are different. The changes mean thate.g. /region=“France”/ now covers only metropolitan France, whithout(most of) the overseas departments and territories - Someinconsistencies in the naming procedure remain. For instance, while mostcountries are named by their full name, “UK” and “USA” are shortened inthe same way as in the old data base. For UK, this even required a hackin the mapping code to avoid adding Ukrain to the map. - The iso3166table may have to be adapted for the Natural Earth 1:10 database, someextra rows have already been inserted.