GIS Lecture 4: Data. GIS Tutorial, Third Edition GIS 1

Transcription

1 GIS Lecture 4: Data GIS 1

2 Outline Data Types, Tables, and Formats Geodatabase Tabular Joins Spatial Joins Field Calculator ArcCatalog Functions GIS 2

3 Data Types, Tables, Formats GIS 3

4 Directly Loadable Data Types dbase (.dbf) - field name maximum length of 10 characters Text with comma- or tab-separated values (.csv) Microsoft Access (.mdb) Excel (.xls) GIS 4

5 Proper Data Table Formats First row must be the field names -(e.g., Pop5To17, Area, and Capacity) Field naming convention -first character is a letter -remaining characters be any letters, digits, or the underscore character (no spaces) All additional rows of a data table contain attribute values GIS 5

6 Data Types GIS 6

7 ESRI Data Types Shapefile - older format - actually made up of 4 files (shp, shx, dbf, prj) Geodatabase - newer format - relational database - similar to Access database -.gdb file extension GIS 7

8 Geodatabases Geodatabase with multiple data types GIS 8

9 Geodatabases Manages features, tables, images inside a database management system (DBMS) Enterprise (ArcSDE) geodatabase -Multiple editors at a time -Requires a host DBMS -SQL Server, Oracle, or IBM DB2 Personal/File geodatabase -Single editor at a time GIS 9

10 Creating New Data GIS 10

11 Import Data Into Geodatabase Shapefiles, data tables, rasters GIS 11

12 Export Data From Geodatabase GIS 12

13 Tabular Joins GIS 13

14 Tabular Joins Putting two tables together to make one table Join with common field attributes Common fields do not need to have the same field names Must have the matching values and data type (e.g., text vs. numeric) GIS 14

15 Tabular Join Example County Property Assessment Assesses the value of each land parcel and its structures and sets a property tax rate (= assessed value * tax rate) GIS 15

16 Property Data w/ no geography Parcel ID, Map Lot Block Number, Address, Value, Sale Date and Price, etc. GIS 16

17 GIS Parcels Layer GIS 17

18 Add Data Table in ArcMap GIS 18

19 Add Parcels Shapefile GIS 19

20 Choose Fields to Join GIS 20

21 Join Data GIS 21

22 Join Result Property fields are added to the Parcels attribute table GIS 22

23 Map with Property Data GIS 23

24 Problems with Joins Data in fields not exactly the same Must remove dashes! GIS 24

25 Problems with Joins Different data field types text numeric GIS 25

26 Spatial Joins GIS 26

27 Spatial join example You have census block group centroid points with housing fuel data You want to know housing fuel data by neighborhoods But there are no attributes in common Spatial join needed GIS 27

28 Spatial joins Points to polygons Spatially joins points (block centroids) within polygons (neighborhoods) Joins using shape (not attribute field) GIS 28

29 Spatial joins Right click polygon layer (neighborhoods) GIS 29

30 Join result New polygon feature GIS 30

31 Join result Count how many points are in each neighborhood Sums adds up the field values within each neighborhood GIS 31

32 Count result Number of points in each polygon GIS 32

33 Sum result One neighborhood example Central business district -4 block groups -Housing units with electricity fuel from block group centroids field [H040004] ( ) -Sum = 799 GIS 33

34 Choropleth map result (sum) GIS 34

35 Field Calculator GIS 35

36 Field Calculator Functions Populate field with county name GIS 36

37 Field Calculator Functions Concatenate house number and street fields GIS 37

38 Field Calculator Functions Calculate Geometry GIS 38

39 ArcCatalog Functions GIS 39

40 ArcCatalog basic functions Copy, paste, rename, etc. View and edit properties View and edit metadata Create new files GIS 40

41 View and edit properties Projections, fields, etc. GIS 41

42 View & edit metadata GIS 42

43 Create new files Geodatabases, tables, features, etc. GIS 43

44 Summary Data Types, Tables, and Formats Geodatabase Tabular Joins Spatial Joins Field Calculator ArcCatalog Functions GIS 44

45 * Tutorial 4 tips * when it asks you if you want to Create an Index, YES this will help ArcGIS process your data faster the Calculation takes a long time to start; it looks like nothing is happening. Be patient! GIS 45

46 Tutorial flowchart Beat polygons Business points Business points with Beat ID field Business points with business type Business points only selection A B A A A B B A 1901 A 5812 A 5813 B 6654 B 1126 A 5812 A 5813 C D C C D C 3314 C 5813 D 2950 C 5813 Spatial Join Business points to Beat polygons Tabular Join Business points to SIC business type codes Query Business points with EatingDrinkingPlaces SIC business type codes ( 5812 or 5813 ) table of Business point counts Beat polygons with Business point counts Map coloring Beat polygons by their Business point counts 2 0 A 2 B C 1 D 0 Summarize Tabular Join Symbolize count of Business points with EatingDrinkingPlaces in each Beat polygon table of Business point counts to Beat polygons color Beat polygons by count of businesses GIS 46