Massachusetts Institute of Technology - Department of Urban Studies and Planning
11.188: Urban Planning and Social Science Laboratory
Lab Exercise 5: Database Aggregation and Chart Creation in ArcMap
In-Lab Notes - 13 March, 2017
Screen Sharing: http://mit.webex.com/join/jf
Key Ideas in Lab #5: (Mapping and charting population density in Mass)
Mapping population density with too-detailed a map -- handling one-to-many relationships in ArcMap
Tricky to map population density when towns may have more than one part (polygon).
Common complication since geometry and data tables come from different sources
More common with detailed (large scale & small area) maps - Boston has more than one 'part'
Constructing meaningful indices (such as population density)
Requires excluding cases and normalizing data
May require creation of new features and attributes in writeable directories.
Charts and business graphics in ArcMap
Another useful dimension: business graphics
Careful about which data gets mapped
Understand the one-to-many linkages among tables
Be aware of selected sets in maps and tables - most operations act on selected sets and you may forget about the selections
Handling one-to-many relationships in MS-Access
Equivalent to 'summarize' command for ArcMap attribute tables (but more powerful)
Need to turn on 'totals' row in the query builder GUI
'Group by' the column(s) you want to collapse into one unique value per row
Specify an aggregation function for the other columns (count, sum, average, minimum, ...)
Key Techniques in Lab #5: (Data manipulation in ArcGIS)
Joining attribute tables in ArcMap
Identify matching columns for each table
Direction matters! start with geographic table
Join operation will ignore >1 match to any mapable row!
Summarizing ArcMap attribute tables:
Aggregate/summarize all the other attributes for the rows that have the same value in the 'summarize' column
Highlight the 'group by' column (where each unique value results in one output row)
Select other columns that you wish to aggregate (via 'count,' 'sum,' 'max,' etc.)
Charting the correct table
May need to 'summarize' a table before charting
Be careful about which table to join to maps (i.e., the one-to-one table
after
summarization)
Selecting on map can impact chart as well as highlighting attribute table rows (if correct tab is checked)
Copying web services into ArcMap from earlier ArcMap documents
Open 11.188_lab2_web.mxd and copy web services into your Lab #5 document
Moving tables from ArcGIS into MS-Access
Last modified on 8 March 2017 [hongmou].
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