Geocoding Reference USA data in ArcMap 9.3

Transcription

1 Tufts GIS Tip Sheet Geocoding Reference USA data in ArcMap 9.3 Written by Barbara Parmenter Revised 3/1/2011 In this exercise, you will map businesses or services for a town in the Boston metropolitan area You ll use Reference USA, an online business database for which Tufts Library has a subscription. You ll search for businesses on Reference USA using the Census NAICS code (North American Industry Classification System) and a town name. Once you have a list of businesses, you ll download an Excel file, modify it as needed, then map it against the TIGER roads file from MassGIS (Census2000Tiger_Arc). You need to decide on a city (e.g., Somerville) and a type of business or service, and then finds its NAICS code. For a NAICS example, let s say you re interested in grocery stores. Go to the Census NAICS code web site - above the 2007 NAICS search box on the left, type in Grocery Store and press the Search button: Getting Business Data from Reference USA by NAICS and Zip Code 1. Go to the Tufts Tisch Library site Click on Articles/Databases and search for Reference USA 3. click on Reference USA link in the results (if you didn t use quotation marks, you may have to scroll down the page 4. Once in Reference USA, click on U.S. Businesses 5. Click on the custom search tab. 1

2 6. On the left, click Expand All 7. Click the buttons Keyword/SIC/NAICS and City. 8. Carefully follow the 5 steps below in this example we are searching for grocery stores (45110) in Somerville, but you can choose other NAICS and other cities: Note that you can enter more than one NAICS code and more than one city. For example, you could search for both grocery stores (45110) and convenience stores (445120) Note: As an alternative to typing in a NAICS code, you can choose to search using a keyword. Notice that the text box below the search box updates as you type. Type slowly until you have a narrow enough set of choices. Select the codes you want by clicking on them in the top box ( Results ); to remove one from your list, click on it in the second box ( Selected ). Notice that many categories have different numbers but the same classifications; for a detailed listing of what each NAICS code means, see 2

3 9. On the results screen, you need to select the businesses of interest (we have 31 returns for Somerville). We want all of them, so check the box at the top of the first column as shown here: 10. If you have a second page of results, go to page 2 and click on the same box again Note: If you have more than 2 pages of results, that means you have over 50 records. You can only download 50 records at a time. So stop at 50. If you need to do the rest later you have to clear the first two pages of selections (uncheck the selection boxes) and then select the next two pages. 11. Click the download button. 12. Fill out the form as you see below, adding Latitude and Longitude to the default fields. If you downloaded information for more than one NAICS, then add the Primary NAICS Code and Primary NAICS Description as well: 3

4 13. When finished, click Download Records and choose to open it with Excel if you get a warning message about formats, choose Yes to open the file 14. Before proceeding, choose Save As to save the file to your H: drive with a name like Somerville Grocery Stores do not use hyphens in your file name! You can save it as Excel 2007 or both formats should work. 15. If you had more than 50 results, go back to your results table, deselect the first two pages of results (click on NONE at the top of the left column), and select the next two pages. Run through the download process again. This will create a second Excel file. You can copy and paste the rows of data from the second sheet to the end of the first sheet to make one big Excel table of all your data. Modify your Excel File 1. Rename the worksheet to something more comprehensible like Grocery Stores (no hyphens!) 2. There is one additional problem we need to correct in the Excel file the latitude and longitude columns are text and they need to be numbers with 6 decimal places. a. Highlight all the Latitude and Longitude data cells (not the column names) b. Click on the little message diamond ( ) and choose Convert to Number 3. Save your file and Exit out of Excel (this is important you cannot have your Excel file open when you work with it in ArcMap). Create an Address Locator to prepare the Study Area Tiger Streets 1. Start ArcMap to a new map, and add the CENSUS2000TIGER_ARC.shp from M:\State\MA\MassGIS\Census_ this line file includes all lines from the TIGER data (e.g., roads, water, city limits) the type of feature each line represents is coded in the CFCC attribute field (Census Feature Class Code all codes starting with A refer to street centerlines) 2. Zoom to the area for which you want to map businesses 4

5 3. Open your CENSUS2000TIGER_ARC attribute table 4. Look to find the address ranges and zip code information - what are the fields are called? Note that there are 4 zip code fields - two are lacking the leading zero s. You will need to use the ones with the leading zero s there is one indicating the left side of the street zip code and another the right (ZipL_C and ZipR_C) 5. Open ArcToolbox ( ) - Gecoding Tools and double-click on Create Address Locator 6. Click on Show Help in the bottom right corner of the dialog box for context sensitive help (you can click on the Help icon in that box for detailed instructions). 7. Fill out the dialog box as you see on the right: a. Click on the folder next to Address Locator Style to choose a style choose US Streets with Zone the zone will be the zip code). b. Under Reference Data, use the pulldown arrow and choose CENSUS2000TIGER_ARC.shp c. Under Role click and select Primary table Primary is always the most common choice. Alias is used for when a place has an address (90 Congress St.) but is also known as something else (Government Center) d. The Field Map table will populate after you make your selection. Note that the Left Zone and Right Zone did not fill correctly you need it to be the ZipL_C and ZipR_C respectively, as shown in the illustration The field map links required information to fields in the street GIS data set s attribute table. Check to ensure everything is filled in correctly and fill in blanks as needed. e. Under Output Address Locator, give the new file a name that reflects the reference data (e.g., TIGER_Streets_Locator) and store it on your H: drive I suggest you put it into a folder called AddressLocators). f. Click OK. The process will take a couple minutes. Stretch time! 8. When finished, close ArcToolbox Geocode your Business Data 1. Add your Excel table to ArcMap (use the Add Data icon - you have to navigate one step beyond the.xls file to choose the individual worksheet, e.g., Grocery Stores$ ) 5

6 2. From the ArcMap menu (NOT the Toolbox), choose Tools Geocoding Geocode Addresses 3. Your address locator that you created earlier should appear highlight it and click OK (if it doesn t appear, click on Add and navigate to where you saved it and add it. 4. In the next dialog box, select your Reference USA-based Excel file (again, it s named something like this Custom $) as the Address Table 5. For Street or Intersection choose Address this is the name of the column that has the address in the Excel file. 6. For Zone, choose Zip Code - this is the name of the column that has the zip code in the Excel file. 7. Take a look at Geocoding Options it has options for off setting the point so that it doesn t fall right in the street, and a few other things. Make sure it is offset some amount (20 feet is fine). Press OK. 8. Make sure to specify an output name and location e.g., geocoding_results_somerville_grocery_stores.shp 9. Click OK to exit from this dialog box 10. Examine the geocoding results summarized in the new dialog box. 11. Press CLOSE. 12. Your geocoded points will appear on the map. 13. We ll go over how to deal with your unmatched records in class. For more guidance, go to ArcGIS 9.3 Help Geocoding Locating Addresses Rematching a Geocoded Feature Do a Data Quality Assessment! You should now have points on your map. But just because addresses found a matching street address range doesn t mean they are in the right place. Explore the placement of your data points to see if they are accurate enough for your purposes. You can add the World Imagery from ArcGIS Online for reference. You will also need to try and match the unmatched addresses (look at the ArcGIS Help for more information). The match score will also give you limited information about the quality of the match a lower match score indicates that fewer match criteria were met. But even where it says 100 for the score, you need to check the placement. 6

7 Adding Reference USA data using its latitude and longitude information You can also add data to ArcGIS without address matching if the data set has x and y coordinates. The Reference USA data should have your corrected latitude and longitude fields. If so you can map these. 1. In ArcMap under the Tools menu function, Add XY Data. 2. Fill the dialog box out as follows, with your table instead of the one shown. Make sure you choose Edit to select the coordinate system then Select. Choose Geographic Coordinate System - World WGS Press OK read the warning but then press OK again. 4. The points should appear on a map. For detailed instructions about adding tabular xy data to ArcGIS based see the ArcGIS Desktop Help under ArcMap Creating Maps Adding XY Coordinate Data to a Map Tips to keep in mind when adding XY data: When the data initially comes up as points in a map, ArcGIS refers to it as an events layer this is a temporary, virtual view of your tabular data. To make it into a permanent shape file which you can edit and use in analysis, export the events layer to a shape file by right-clicking on the points events layer, and choosing Data-Export when the export dialog box comes up, you can choose to export the data into the data frame s 7

8 coordinate system so that it matches your other data. Again, check the data quality of the newly added points. Which method resulted in the best position? How do you think Reference USA geocoded its data? Try geocoding against other data sources You can geocode against StreetMap USA and/or Parcel Polygons or Address Points if they are available the most important thing you need to do is create a correct address locator. Once you have done one or both of these, compare your results with the TIGER geocoded data. Which reference layer would be better for your project? You will need to examine the attribute fields before you create the address locator to see how to map the fields. StreetMap USA note There is already an address locator created by ESRI for StreetMap USA it is located on the M: drive with the data (M:\Country\USA\ESRIDataMaps906\streetmap_usa\streets\StreetmapUSA). To access it for geocoding: 1. Click on choose Tools Geocoding Geocode Addresses 2. In the box asking you to choose an Address Locator, click on ADD 3. Navigate as shown below: 8

9 4. Click on the StreetMap USA address locator (note what an address locator icon look like) and click ADD 5. click OK 6. Fill out the Geocode Addresses Form as follows (except create a output shapefile on your H: drive) note this address locator has more components including city and state: 7. Click OK 8. Examine the points on the map in comparison with where they were when you geocoded them against TIGER Roads. Boston Parcels note: The file to use for Boston Parcels is ParcelsFY09.shp (located on M: drive -M:\City\Boston\Assessor) The style for Boston parcels should be One Address with Zone (if you are using the Zip Code) below is an example I did for Boston Parcels 9

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