JMP Product Manager Jeff Perkinson presented the April 14 Mastering JMP session, Using Geographic and Custom Maps. I divided his demo into three parts for you to watch at your leisure.
By default, JMP installs map files in a Maps directory. Each map consists of two JMP data files with a common prefix:
- -Name file that contains the unique names for the different regions.
- -XY file that contains the latitude and longitude coordinates of the boundaries.
The two files are implicitly linked by a Shape ID column. For example:
- The World-Country-Name.jmp file contains the exact names and abbreviations for different countries throughout the world.
- The World-Country-XY.jmp file contains the latitude and longitude numbers for each country, by Shape ID.
The Shape ID strings in the -Name and -XY .jmp files must match. Hint: If JMP does not recognize the names in your data, check the built-in map files for spelling and names that JMP recognizes. For example, United Kingdom is a country name, but Great Britain is not.
Here are some of the questions that arose during the webcast and corresponding answers provided by Jeff and JMP Developer Xan Gregg.
Q: Do the built-in maps use the 1984 WGS projection definitions?
A: JMP uses one of two projections when the axes are set to "geodesic" scaling. For the whole world, JMP uses a projection called Kavrasky 7, which is similar to that used by National Geographic. For more local areas, like the US Map, JMP uses the Albers equal-area projection used by the US Geologic Survey. That method lets JMP compare filled areas accurately.
Q: What are Choropleth maps?
A: Choropleth maps, such as those you can display in JMP using .shp files, shade or give patterns to areas in proportion to the measurement of the statistical variable being displayed on the map. This lets you visualize differences across a geographic area.
Q: Do you have a list of ZIP codes with longitude and latitude built into JMP or know where I can find them?
A: ZIP code shapes are not included with JMP. The .shp files for them can be downloaded from the US Census Bureau one state at a time.
Q: Do Simple Earth and Detailed Earth maps show detail to 1 square mile?
A: Simple Earth and Detailed Earth are not high enough resolution to be used for drawing 1 square mile. It will attempt to display, but you will see “fat pixels.” To zoom in to that level of detail, you may try one of the maps offered on the NASA server.
Q: Does JMP support SAS/GRAPH maps?
A: SAS/GRAPH includes map data sets that can be converted for use as shape (.shp) files with JMP. These data sets are in the JMP Maps library. They come as a pair of data sets just where the traditional map data sets contain the XY coordinate data. The feature table contains the common place names.
Most of the traditional map data sets include unprojected latitude and longitude variables in radians. They can be used with JMP after they’ve been converted to degrees and the longitude variable has been adjusted for projection.
To convert SAS maps, you can download the SAS map to JMP map converter from the JMP File Exchange using your SAS login.
Q: In the past, SAS GIS has had difficulty importing .shp files that are donuts, or polygons within polygons. Does JMP overcome that issue?
A: JMP does support shapes with holes. South Africa is one example. Also, SAS/GRAPH includes a number of map data sets that can be converted for use as shape files with JMP. These data sets are in the JMP Maps library.
Q: Please share with us the steps for adding a .shp file.
A: Mike Vorburger's blog post describes the steps and gives information about locating .shp files.
Q: Where do we save our .shp files?
A: Save the .shp files to the same place as the built-in files, in the Maps folder, and JMP will automatically find them. The locations differ according to operating system:
A: Some government agencies, such as the US Census Bureau, offer free files, including a variety of recent TIGER/Line®Shapefiles that contain features such as roads, railroads, rivers, as well as legal and statistical geographic areas. Other commercial Geographic Information System businesses, such as ESRI and the ESRI map service ARCGIS, also offer map shapes.Q: Jeff said that the NASA map server changed location after JMP 9.0 was released, so the JMP built-in link to the NASA server is no longer accurate. When will it work?
A: We updated JMP 9.0.2 to link to the new NASA server location. You can download the update by May 1 from the JMP Software Updates page in the Support area of our website.
A FINAL TIP: Want to set JMP to look for updates today or regularly (daily, weekly or monthly)? Just specify your wish using JMP File>Preferences>JMP Updates.