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Lecture 4 Geodatabases

Lecture 4 Geodatabases. Geodatabases Outline. Data types Geodatabases Data table joins Spatial joins Field calculator Calculate geometry ArcCatalog functions. Lecture 4. Data types . Directly loadable data types. dBase (.dbf) Text with comma (.csv) or tab-separated values (.txt)

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Lecture 4 Geodatabases

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  1. Lecture 4Geodatabases

  2. Geodatabases Outline INF385T(28437) – Spring 2013 – Lecture 4 Data types Geodatabases Data table joins Spatial joins Field calculator Calculate geometry ArcCatalog functions

  3. Lecture 4 Data types INF385T(28437) – Spring 2013 – Lecture 4

  4. Directly loadable data types INF385T(28437) – Spring 2013 – Lecture 4 • dBase (.dbf) • Text with comma (.csv) or tab-separated values (.txt) • Microsoft Access (.mdb) • Microsoft Excel (.xls)

  5. Data table formats INF385T(28437) – Spring 2013 – Lecture 4 • First row must have attribute names with self-documenting labels • (e.g. Pop5To17, Area) • Usual naming convention • first character is a letter • remaining characters be any letters, digits, or the underscore character • All additional rows of a data table contain attribute values • None of the rows can be sums, averages, or other statistics of raw data rows

  6. Lecture 4 geodatabases INF385T(28437) – Spring 2013 – Lecture 4

  7. Geodatabase types INF385T(28437) – Spring 2013 – Lecture 4 Manages features and tables inside a database management system • File geodatabase • stores datasets in a folder of files • each dataset file up to 1 TB in size • can be used across platforms • can be compressed and encrypted for read-only, secure use

  8. Geodatabase types INF385T(28437) – Spring 2013 – Lecture 4 • Personal geodatabase • stores datasets in a Microsoft Access .mdb file • storage sizes between 250 and 500 MB • limited to 2GB • only supported on Windows • ArcSDE geodatabase • stores datasets in a number of optional DBMSs: • IBM DB2, IBM Informix , Microsoft SQL Server , Oracle, or PostgreSQL • unlimited size and users

  9. New file geodatabase INF385T(28437) – Spring 2013 – Lecture 4 ArcCatalog

  10. Import into geodatabase • Shapefile features INF385T(28437) – Spring 2013 – Lecture 4

  11. Import into geodatabase INF385T(28437) – Spring 2013 – Lecture 4 Tables

  12. Export from geodatabase INF385T(28437) – Spring 2013 – Lecture 4

  13. View geodatabases INF385T(28437) – Spring 2013 – Lecture 4 Cannot identify names in Windows Explorer Must use ArcCatalog

  14. Compact geodatabases INF385T(28437) – Spring 2013 – Lecture 4 • File and personal geodatabases • Reduces size and improves performance • Compact personal geodatabases > 250 MB. • Geodatabases with frequent data entry, deletion, or general editing • Open geodatabases in ArcMap cannot be compacted • remove any layers with a source table or feature class in that database from the TOC

  15. Compress geodatabases INF385T(28437) – Spring 2013 – Lecture 4 • File geodatabases • Once compressed, a feature class or table is read-only and cannot be edited • Compression is ideally suited to mature datasets that do not require further editing • Compressed dataset can be uncompressed to return it to its original, read-write format

  16. Lecture 4 Data table joins INF385T(28437) – Spring 2013 – Lecture 4

  17. Data table joins INF385T(28437) – Spring 2013 – Lecture 4 Putting two tables together to make one table Join two tables one-to-one by row Must have the same values and data types

  18. Join example INF385T(28437) – Spring 2013 – Lecture 4 • Housing heating fuel study for U.S. Counties • Source: U.S. Census • Data table: Census SF3 table for heating fuel by county • Map Features: County polygons

  19. Data table INF385T(28437) – Spring 2013 – Lecture 4 • Heating fuel table (Excel spreadsheet)

  20. Data table INF385T(28437) – Spring 2013 – Lecture 4 • Heating fuel table data dictionary • H040001: Occupied housing units: House heating fuel; TOTAL Units • H040002: Occupied housing units: House heating fuel; Utility gas • H040003: Occupied housing units: House heating fuel; Bottled; tank; or LP gas • H040004: Occupied housing units: House heating fuel; Electricity • H040005: Occupied housing units: House heating fuel; Fuel oil; kerosene; etc. • H040006: Occupied housing units: House heating fuel; Coal or coke • H040007: Occupied housing units: House heating fuel; Wood • H040008: Occupied housing units: House heating fuel; Solar energy • H040009: Occupied housing units: House heating fuel; Other fuel • H040010: Occupied housing units: House heating fuel; No fuel used

  21. Feature class INF385T(28437) – Spring 2013 – Lecture 4 County polygons

  22. Add data and features to map INF385T(28437) – Spring 2013 – Lecture 4

  23. Open attribute tables INF385T(28437) – Spring 2013 – Lecture 4 Find common attribute to join

  24. Data problem INF385T(28437) – Spring 2013 – Lecture 4 FIPS has leading zero and is a TEXT field. GEO_ID2 is a NUMBER fieldwith no leading zeros.

  25. Data solution INF385T(28437) – Spring 2013 – Lecture 4 Make a new NUMBER field in Counties attribute table and use field calculator to populate new field from old

  26. Data solution INF385T(28437) – Spring 2013 – Lecture 4 New FIPS_NUM is same as GEO_ID2 and ready to join

  27. Join tables INF385T(28437) – Spring 2013 – Lecture 4

  28. Join result INF385T(28437) – Spring 2013 – Lecture 4 Heating fuel data is now listed for every county in the USCounties feature attribute table

  29. Permanent joins INF385T(28437) – Spring 2013 – Lecture 4 Joins are temporary and can be removed Export data to make joins permanent

  30. Choropleth map result INF385T(28437) – Spring 2013 – Lecture 4

  31. Lecture 4 Spatial joins INF385T(28437) – Spring 2013 – Lecture 4

  32. Spatial join example INF385T(28437) – Spring 2013 – Lecture 4 You have census block group centroids with housing fuel data You want to know housing fuel data by neighborhoods No attributes in common Spatial join needed

  33. Spatial joins INF385T(28437) – Spring 2013 – Lecture 4 • Points to polygons • Spatially joins points (block centroids) within polygons (neighborhoods) • Joins using “shape” (not attribute field)

  34. Spatial joins INF385T(28437) – Spring 2013 – Lecture 4 Right click polygon layer (neighborhoods)

  35. Join result INF385T(28437) – Spring 2013 – Lecture 4 New polygon feature

  36. Join result INF385T(28437) – Spring 2013 – Lecture 4 Counts and sums

  37. Count result INF385T(28437) – Spring 2013 – Lecture 4 Number of points in each polygon

  38. Sum result INF385T(28437) – Spring 2013 – Lecture 4 • Every block group centroid has associated data • (e.g. H040004, heating electricity shown in labels)

  39. Sum result INF385T(28437) – Spring 2013 – Lecture 4 • One neighborhood example • Central business district • 4 block groups • Housing units with electricity fuel (80 + 299 + 128 + 292 ) • Sum = 799

  40. Choropleth map result (sum) INF385T(28437) – Spring 2013 – Lecture 4

  41. Choropleth map result (sum) INF385T(28437) – Spring 2013 – Lecture 4

  42. Other spatial joins INF385T(28437) – Spring 2013 – Lecture 4 • Polygons to points • Example: ATM robberies (points) need neighborhood name

  43. Polygon to point join result INF385T(28437) – Spring 2013 – Lecture 4 Neighborhood name shows on each point

  44. Other spatial joins INF385T(28437) – Spring 2013 – Lecture 4 • Points to points • Example: What is the distance of a burglary to the nearest commercial property?

  45. Point to point join result INF385T(28437) – Spring 2013 – Lecture 4 Distance to nearest commercial property shows on each burglary point

  46. Lecture 4 Field calculator (as in “Feature-Attribute” Calculator) INF385T(28437) – Spring 2013 – Lecture 4

  47. Sample functions INF385T(28437) – Spring 2013 – Lecture 4 Performs numeric calculations Populates field Concatenates textdata

  48. Field calculator functions INF385T(28437) – Spring 2013 – Lecture 4 Calculate acres to square miles

  49. Field calculator functions INF385T(28437) – Spring 2013 – Lecture 4 Populate field with county name

  50. Field calculator functions INF385T(28437) – Spring 2013 – Lecture 4 Concatenate house number and street fields

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