This section illustrates steps to access and use shapefiles with integrated demographics for thematic mapping and geospatial analysis using DDA.
With DDA running, the File>GetShapefile operation is selected.
The Honolulu County 2010 Census Blocks shapefile is selected:
Download prepares to start:
Download completes in seconds and the expanded/upzipped shapefile in now on user computer ready for use.
Tools>DBMerge is started.
All items from c:\dda\extract1.dbf (see more about developing this file) are merged into the block shapefile dbf for census block level (sumlev='101') records. None, one or more items can be moved in any order from the Source File 1 and Source File 2.
Only the field GEOID10 is moved from the original shapefile dbf.
Only selected fields are moved from the extract1.dbf file.
At the end of processing, Source File 1 is optionally overwritten with the new temporary "newmerge.dbf."
The filter operation is used to select blocks only since the file extract1.dbf contains summary data for multiple types of geography.
The file extract1.dbf contains block level data for only one census tract, illustrating that not all of the county tracts/blocks need to be available.
Unmatched shapefile block records have the field created but it remains unloaded if no block demographic records are found.
After matching is completed, DDA is used to open the shapefile dbf and show a portion of block records loaded with demographic items.
Viewing the Demographics via GIS
The shapefile with integrated demographics is added to a CommunityViewer GIS project.
The identify tool is used to show a profile for census block 2000 (see pointer) in tract 001904.
A thematic map showing patterns of Percent Asian population by census block (in tract 19.04).