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GIS Lecture 4Geodatabases

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Outline

•Administrative Data Example•Data Tables•Data Joins•Common Datasets•Spatial Joins•ArcCatalog•Geodatabases•Editing Tables•Excel Tips

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Administrative Data Example

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Administrative Data

Mission • What does the organization do?• Transaction event (who, what, where, when)-must have spatial component

What data is available? • Databases• Spreadsheets

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Example

Kaiser Family Foundation•non-profit, private operating foundation focusing on the major health care issues facing the nation

•independent voice and source of facts and analysis for policymakers, the media, the health care community, and the general public

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Kaiser Family Foundation State Health Facts

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Collects Data on all 50 States

•Demographics and the Economy•Health Status•Health Coverage and Uninsured•Medicaid and SCHIP•Medicare•Health Costs and Budgets•Managed Care and Health Insurance•Providers and Service Use•Minority Health •Women’s Health•HIV/AIDS

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Data Tables

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Download Data

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Download Data

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Open data in Excel

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Data in Excel

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Clean Data in Excel

•Delete Unnecessary Data

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Save Database

Saved as .CSV or .DBF

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Data Joins

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Add Data Table in ArcMap

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Add Shapefile

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Choose Fields to Join

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Join Data

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Fields Added to States Table

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Problems with Joins

Must remove dashes!

• Data in fields not exactly the same

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Common Problems with Joins

•Different data field types

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Problems with Joins

•Saving .DBF and .CSV files in Excel•Avoid special formats•Keep it simple

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Number Fields Important

•Quantities

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Common Datasets

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Common Datasets U.S. Census Maps and U.S. Census Tables

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Common DatasetsZip Codes-Use with U.S. Census data or Geocoding

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Place Geocodes: FIPS Codes

Federal Information Processing Standards Codes

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

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Place Geocodes: Hierarchy

Country: US

FIPS CODES

County: 003 (Allegheny)

State: 42 (Pennsylvania)

Tract: 0501

Block: 12 (US420030501312)

Block Group: 3CENSUS CODES

Minor Civil Division: 85188 (Wilkinsburg)

Parcel (Block & Lot#)

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Other Datasets

•Contact agencies•Obtain data on-line

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Spatial Joins

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Spatial JoinsSpatially count points within polygonsJoin tables using Shape fieldJoin points to polygons or polygons to points

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Spatial JoinsJoin municipality name to points spatially

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Spatial Joins Resultant point layer (food points) now contains municipality information

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Aggregate Data

Summarize on spatial join- Counts the number of points (records) for each

municipality

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Aggregate Data

Resultant Table- Count of points (food stores) in each polygon

(municipality)

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Join Summary Table Join summary table of counts (based on municipality name from sum table) back to municipalities for labeling

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Label CountsLabel the count of stores from the summary join

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Label CountsShow counts as a Choropleth Map

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Map with Points

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Map without Points

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ArcCatalog

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ArcCatalog

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Metadata

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Metadata

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Metadata

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Metadata

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Metadata

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Geodatabases

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Geodatabase

•Represents geographic features and attributes as objects and is hosted inside a relational database management system

•Manages coverages, grids, and shapefiles inside a database management system, or DBMS

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Enterprise Geodatabases

•Requires a ‘host’ DBMS -SQL Server, Oracle, or IBM DB2

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Personal Geodatabases

•Based on the Microsoft JET engine -Appears as an .mdb file (Microsoft’s JET engine is also used by Microsoft Access).

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Geodatabase Advantages

•Geodatabases have several important advantages over the traditional file-based GIS data models-Makes GIS datasets smarter-More accurately represent the shape of features-Provides a uniform and IT compliant repository for geographic data-Many users can edit geographic data simultaneously

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Geodatabases

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Importing Shapefiles into Geodatabases

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Importing Tables into Geodatabases

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dBASE and Tables

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dBASE Tables

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Editing TablesField definitions edited in ArcCatalogLayers cannot be in use elsewhere

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Calculator Functions

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Calculator FunctionsNot just for numeric fields

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Excel Tips and Tricks

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Excel Tips and Tricks

•Formatting•Find and Replace•Transpose•MID Function•Concatenate

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Formatting and Replace

•Delete any Excel formatting (e.g. borders, patterns, etc.)

•Delete unwanted text (e.g. word “tract”)-Find and replace

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Transpose Data

•Transpose data-Some census data saves data as rows instead of columns

-You need transpose the data so that tracts will be a column-Select your data in excel and go to Edit menu and select copy-Click on a cell outside of your selected data and go to edit menu to select paste special…

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Now you see the data transposed in the right way. All you need to do is to delete the original rows and save your file.

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Mid Function

Sometimes, a simple replace won’t do for you to substring a column. In this case, you can use Excel’s mid function to get a subset of a value.For example, if you have the following data want extract two letters in the middle, say 12 from the first row, and 13 from the second row, and so on, the Excel MID function is your choice.

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Mid Function

You enter: =mid(A1,4,2) in the cell next to A1. What you tell excel to do is: From cell A1, extract 2 characters starting from the 4th character from left.

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Mid Function

Then you copy and paste the formula from B1 to the rest of the column and you get what you need.

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Concatenate Strings

Sometimes you need add certain string before or after a value, and sometimes you want to combine two values. The excel CONCATENATE function makes that happen for you.

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If you have the below dataset, and want to combine the state ID and county ID together as another variable and you want to make sure the new StateCountyID has the length of 5

For example, you want to add a “0” to State IDs that are only 1 character long, and you want add “00” to county IDs that that is 1 character long and “0” to those that are 2 characters.

Concatenate Strings

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Start by adding a new column right to StateID, and enter:

=IF(LEN(A2)=1,CONCATENATE(0,A2),A2)

What you tell excel is: if the length of the cell A2 is 1, add 0 before the original value, otherwise, keep the original value

Concatenate Strings

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After that, you copy and paste the formula to the rest of the column, and you will see the following result

Concatenate Strings

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Now let’s solve the problem for county ID. In the cell next to C2, you enter:

=IF(LEN(C2)=1,CONCATENATE("00",C2),IF(LEN(C2)=2,CONCATENATE("0",C2),C2))

What this tells excel is if the length of county ID is 1, add “00” before it, if the length is 2, add “0” before it, if the length is 3, keep the original

Concatenate Strings

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Now you copy and paste the formula to the rest of the column and you get the above result

Concatenate Strings

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Next, you create a new column called StateCountyID, and enter is the cell E2:

=concatenate(B2,D2)

By this, you are telling Excel to combine the two new columns that you created in the previous steps

Concatenate Strings

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Now you just need to copy and paste the formula to the rest of the column and you finally get what you want.

Concatenate Strings

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Other Excel Functions

You might want to learn some other excel functions that could help you clean the data, such as:• Right()• Left()• Exact()

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Summary

•Administrative Data Example•Data Tables•Data Joins•Common Datasets•Spatial Joins•ArcCatalog•Geodatabases•Editing Tables•Excel Tips