Presentation is loading. Please wait.

Presentation is loading. Please wait.

GIS 1 Attribute Tables. GIS 2 Data table format Rectangular table with one value per cell - Columns (fields) are attributes - Rows are observations (data)

Similar presentations


Presentation on theme: "GIS 1 Attribute Tables. GIS 2 Data table format Rectangular table with one value per cell - Columns (fields) are attributes - Rows are observations (data)"— Presentation transcript:

1 GIS 1 Attribute Tables

2 GIS 2 Data table format Rectangular table with one value per cell - Columns (fields) are attributes - Rows are observations (data)

3 GIS 3 Data table format First row must have column names that are self- documenting labels - e.g., Pop5To17, Area - First character is a letter - Remaining characters can be any letter, digit, or the underscore character (but no blanks) All additional rows of a data table must contain only attribute values - None of the rows can be sums, averages, or other statistics for other rows Sometimes columns can be functions of other columns (sums, averages, etc.)

4 GIS 4 Primary keys Each data table has a primary key with two properties - Each value in the attribute column is unique - There are no null values

5 GIS 5 FIPS Geocodes Federal Information Processing Standards - Developed by the National Institute of Standards and Technology - Codes for place names throughout the world –countries –states/provinces –counties –metropolitan statistical areas (MSA’s) –cities –places - Indian reservations, airports, and post offices in the US See http://www.genesys- sampling.com/pages/Template2/site2/61/default.aspx for additional geocodes.http://www.genesys- sampling.com/pages/Template2/site2/61/default.aspx

6 GIS 6 FIPS Geo codes: Hierarchy Country: US FIPS codes County: 003 (Allegheny) State: 42 (Pennsylvania) Tract: 0501 Block: 12 (US420030501312) Block Group: 3 Census codes Minor Civil Division: 85188 (Wilkinsburg) Parcel (Block & Lot#) Local government cadastral data

7 GIS 7 ANSI Codes American National Standards Institute (ANSI) Codes www.census.gov/geo/www/ansi/ansi.html Replaces FIPS codes In many cases, the codes are the same (e.g. Pennsylvania, Allegheny County = 42003)

8 GIS 8 External table file formats for import to ArcGIS Plain ASCII text with comma separated values (.csv ) - Very transportable format, very large files - Each table record is a row terminated with a line-break character - Has values separated by a delimiter, usually a comma - For data values that contain the delimiter, enclose the value in double quotes - Sometimes columns get wrong data type on import (use double quotes to force text data type for digits, say for house numbers)

9 GIS 9 External table file formats for import to ArcGIS Excel (.xls,.xlsx) - Excel 2003, up to 65,000 rows and 256 columns - Excel 2007, up to 1,048,576 rows and 16,384 columns dBase database table(.dbf) - Legacy format - ArcMap truncates field names to 1 st 10 characters - dBase IV has max of 255 columns - Can open dBase file in Excel but cannot save Dbase from Excel Microsoft Access database (.mdb) - Up to 2GB file size - See following for other limits: http://www.databasedev.co.uk/access_specifications.html http://www.databasedev.co.uk/access_specifications.html

10 GIS 10 Field calculator (numeric)

11 GIS 11 Field calculator (numeric) Calculate acres to square miles

12 GIS 12 Field calculator (text) Concatenate house number and street fields

13 GIS 13 Field calculator (text) Populate field with county name

14 GIS 14 Data Table Joins

15 GIS 15 Joins Feature attribute tables, data tables Puts two tables together, on the fly, to make one table - One-to-one join - One-to-many join

16 GIS 16 Example join = U.S. Counties GIS layer Unemployment databases +

17 GIS 17 Determine Fields to Join

18 GIS 18 Create New Field

19 GIS 19 Columns Ready to Join

20 GIS 20 Join Data Right-click Counties layer > Joins and Relates > Join

21 GIS 21 Resultant Attribute Table

22 GIS 22 Classifying Unemployment Values will only appear with number fields

23 GIS 23 Final Map Percentage Unemployment by U.S. Counties, 2005

24 GIS 24 Problems with Joins Field types are different (e.g. one is numeric and one is text)

25 GIS 25 Problems with Joins Data is different Must remove dashes!

26 GIS 26 Problems with Joins Too much formatting in Excel Keep it simple!

27 GIS 27 Spatial Joins

28 GIS 28 Spatial Joins Joins using shape (not attribute field) Enables data aggregation (counting or summing points by polygon) Common Spatial Joins - Points to Polygons (counts) - Polygons to Points (adds text) - Points to points (distances)

29 GIS 29 Points to polygons How many convenience stores are in each neighborhood? Start with: - Store points - Neighborhood polygons

30 GIS 30 Points to polygons Right-click neighborhoods > Joins and Relates > Join

31 GIS 31 Spatial join result New polygon layer with count of points (number of stores)

32 GIS 32 Spatial join result Show as a choropleth map, with labels, or table NeighborhoodStore Count Bloomfield22 Central Business District12 Strip District10 Brookline10 Central Lawrenceville8 Larimer8 Middle Hill7 Central Oakland7 Squirrel Hill South7 South Oakland7 Carrick7 Highland Park6 Garfield6 North Oakland6 Terrace Village6 Brighton Heights5 Shadyside5 Morningside4 Marshall-Shadeland4 East Liberty4 Friendship4 Sheraden4 Homewood South4 Greenfield4

33 GIS 33 Polygons to points What neighborhood is a store in? Start with: - Store points - Neighborhood polygons

34 GIS 34 Polygons to points Right-click business points> Joins and Relates > Join

35 GIS 35 Spatial join result Point shapefile with neighborhood data on each store

36 GIS 36 Points to points How close is a school to a store? Start with: - Store points - School points

37 GIS 37 Points to points Right-click school points> Joins and Relates > Join

38 GIS 38 Result Join

39 GIS 39 Geodatabases

40 GIS 40 Geodatabases A geodatabase is a container used to hold a collection of datasets (GIS features, tables, raster images, and other objects). Country layer Graticule layer World.gdb

41 GIS 41 Geodatabase types File geodatabase (.gdb) stores datasets in a folder of files each dataset a file up to 1 TB in size can be used across platforms can be compressed and encrypted for read-only, secure use ESRI’s recommended choice

42 GIS 42 Geodatabase types Personal geodatabase (.mdb) stores datasets in a Microsoft Access format 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

43 GIS 43 New file geodatabase ArcCatalog

44 GIS 44 Import into geodatabase Shapefile features

45 GIS 45 Import into geodatabase Tables

46 GIS 46 Export from geodatabase

47 GIS 47 View geodatabases Cannot identify names in Windows Explorer Must use ArcCatalog

48 GIS 48 Compact geodatabases 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

49 GIS 49 Compress geodatabases 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

50 GIS 50 ArcCatalog

51 GIS 51 ArcCatalog utility program Like Windows Explorer but for Esri-format data Copy, delete, rename, move, search files, view metadata Import/export popular spatial data format files Create new shapefiles, file geodatabases, etc. for input in ArcMap

52 GIS 52 Basic functions Copy, paste, rename, etc.

53 GIS 53 View and edit properties Projections, fields, etc.

54 GIS 54 View metadata

55 GIS 55 Edit metadata

56 GIS 56 Create new files Geodatabases, tables, features, etc.

57 GIS 57 Calculating Geometry

58 GIS 58 Point Centroids Used to display and calculate data

59 GIS 59 Point centroids When displaying or analyzing small polygons it is often better to use point centroids

60 GIS 60 Calculate XY fields Add new X and Y fields in the attribute table

61 GIS 61 Calculate XY fields Calculate geometry for X field, repeat for Y

62 GIS 62 XY field results Results are X and Y values based on map properties (e.g. Long/Lat or XY feet)

63 GIS 63 Export XY coordinates

64 GIS 64 Add XY data table

65 GIS 65 Export as shapefile XY events should be exported as permanent shapefile or feature class

66 GIS 66 Counting Point Centroids Population spatially joined to buffer around toxic release sites

67 GIS 67 Calculate area Add area field and calculate geometry

68 GIS 68 Calculate perimeter Add perimeter field and calculate script

69 GIS 69 Calculate length Add length field and calculate script


Download ppt "GIS 1 Attribute Tables. GIS 2 Data table format Rectangular table with one value per cell - Columns (fields) are attributes - Rows are observations (data)"

Similar presentations


Ads by Google