Lab3 of Geo520, Spring 2005

TA : Julie Hwang

Lab 3. File Formats across GIS

Working with Selection and Charts

Objectives

The objectives of this lab are to understand the file formats across GIS, to work with the Selection, and to create Charts.

 

File Formats across GIS

______ Scroll down from the Files of type drop-down list in the File Open window to browse through other file formats readable in TransCAD. TransCAD can read some external files directly, and also allows you to import/export them. In this lab, we’re working on external file formats (eg. Shapefiles, ODBC Table).

Using Other Geographic File Formats

TransCAD can import geographic data from many other file formats, including Arc/Info export (e00) files, AutoCAD DXF files, ESRI Shapefiles, Mapinfo Interchange Format (MIF) files, Spatial Data Transfer Standard (SDTS) FILES, Digital Elevation Model (DEM) files, and so on.

Among them, ESRI shapefiles and Map/Info TAB file can be read directly in TransCAD, thus they can be added as a layer similar to TransCAD geographic files.

TransCAD assumes other geographic file formats are stored in geographic coordinate system (eg. longitude and latitude). So if you work on the data from different coordinate system, you may have to set the coordinate system before importing the file.

Using Other Attribute File Formats

TransCAD can read many formats of tabular files. For example, it can read .dbf file, text files, ODBC Table, and so on. If attribute files contain longitude and latitude information in it, TransCAD will prompt you whether to create a layer from them.

 

Practice #1: Create maps using the Map Librarian

______ Check the Open the Map Librarian radio box when Quick Start dialog box pops up. Click OK. Map Librarian can also be accessed by choosing Map-Librarian….

______ When the Map Librarian dialog box pops up, choose the Tract Demographic Profile from the Choose a Map Category list, and Age-Median Age from the Choose the Map You Want list, and then click OK.

______ In the Find dialog box, choose County in the left hand side, and type in Erie in the text box. Click OK. Choose Erie NY for the next window.

______ Create more maps in the same area, say Commute by Transit or Commute by Walk, using Map Librarians

______ Create more maps in other areas, say your hometown.

Practice #2: Select features by condition

______ Make Census Tract an active layer. Then look at its dataview. It seems that they have all census tract records in the U.S., but you only need to work on Erie county.

______ You can select records by the condition. Choose Selection-Select by Condition…. When the Select by Condition dialog box pops up, type in the appropriate condition in the text box using field, operator and function drop-down list. Type in County = “36029”. The value is the FIPS code equivalent to Erie County in NY State. You can set the name for the selection, here ErieCT by typing in the Set Name textbox (if you don’t give a name, it will be named selection by default).

______ How many census tracts are in Erie County according to the selection?

Parctice #3: Export selected features

______ Choose Tools-Export… making sure the Census Tract is an active layer in Maps. Choose ErieCT from the Export drop-down list, and choose Standard Geographic File from the To drop-down list. Name the file in the Save As window. Keep this file in your home directory because you will need this file for the assignment.

______ Open the geographic file you just exported as a new map.

Practice #4: Create a chart

______ Compute statistics of Erie County census tracts.

______ Write down the total population of Erie County.

______ Create a new field and fill the value in the new field named RatioToTotalPop by dividing SUM by the value of total population you just wrote down. For instance, what is the percentage of male in Erie County?

______ Hide fields you don’t want to look at. Highlight any row from the field Count to the field Std. Dev, and then click  (Hide Columns) or choose Hide in the right mouse click.

______ Highlight the cell as shown below. (You may have to drag the mouse from [Age 85+] to [Age < 5] because the order to drag matters in graphics that will be shown later.)

 

______ Click  (New Chart) next to the Open Dataview toolbar.

______ In the Chart Data dialog box, click OK.

______ In the Chart Properties dialog box, choose the chart type: horizontal bar graph, and edit the chart text: Population Pyramid, Erie NY. Make sure you check Labels check box in the Options frame. You just created a sort of population pyramid because it doesn’t put a male/female in a symmetric manner.

Practice #5. Add ESRI Shapefiles as a layer

______ Click  (Map Layers) in the Erie County map, then click Add Layer button. Choose ESRI shapefile from the Files of Type drop-down list in the File Open dialog box. Locate the shapefile nhpn.shp located in H:\GEO520\Lab3\Shapefile. (For H: drive, find classwrk on yenisey in explorer).

Data source: http://websas.bts.gov/website/ntad03/statedownloadform.html

______ Click OK in the ESRI Shapefile window.

Practice #6. Select features by location

______ Make nhpn an active layer. Choose Selection-Select by Location…

______ Select features of NHPN that are touching Erie Census Tract.

______ Export the selected features of NHPN into standard geographic files. Then add the file as a new layer after you close nhpn layer in shapefiles.

Practice #7. Create a Map Layer from ODBC table

TransCAD allows you to work with ODBC table. For example, if you have already worked with mdb file (MS-Access), you can directly access the content through TransCAD user interface. Mdb file provided in this practice contains NY State hospital attribute table, and a query that selects Erie County hospitals from NY State data. Also note that the data contains longitude and latitude in it, and it is not yet geocoded. You may want to browse through the file in MS-Access to have an idea.

______ Click  (Map Layers), then click Add Layer button. Choose ODBC Table from the Files of Type drop-down list in the File Open dialog box..

______ In the Open ODBC Table dialog box, choose MS Access Database from the Source drop-down list.

______ Locate the nyhosp.mdb located in H:\GEO520\Lab3\ODBC when the Select Database dialog box pops up.

______ Choose sel_Erie from the Choose a Table list, and ID from the Choose a Unique Field list. Note TransCAD automatically geocodes attribute table if the table lon/lat information in it.

Assignments (due at the beginning of next lab):

This time, suppose you are asked to make a presentation concerning how the relationship between poverty level and public transportation varies by localities. Pick two study areas – Erie County and any county of your choice at the level of census tract. Use two fields, [% Transit & Not Home], and [Individuals Below Poverty] which can be found in the right end of dataview of census tract layer. Submit thematic maps, and scatterplots* of those two variables in two study areas.

 

*To create the scatter plot of the whole study area, without highlighting cells, choose All Rows from the Features/Records to includes drop-down list, and choose two fields from Read Data from drop-down list in the Chart Data dialog box (look at the figure at the right). You also need to choose scatter for the Chart Type list in the Chart Properties dialog box.