Address Matching
or "Geocoding"
The following example is based on Geocoding in ArcView3.x, but can be easily
translated to ArcGIS9. Most important is understanding the underlying
logic and how the .ACODE attributes of the TIGER line files are essential
to the process.
Setup:
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Download example address table (graffiti.dbf)
from the Lakewood Tiger archive (laketiger.zip).
[You can create your own Address Database file using a spreadsheet or database]
... place in scratch directory on the local disk.
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Open a New Map.
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ADD the Lakewood TIGER Theme to the map.
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ADD the appropriate Address Table (graffiti.dbf) to the map.
In this exercise, we will be using the Address-Ranges found in the
Attributes of TIGER.shp table to estimate the approximate
street address of each item in an external database (graffiti.dbf). The
approximation is based on the beginning and ending address numbers of each
BLOCK. The address is geocoded by interpolating (estimating)
the point along the block where the address ought to be based on
its street number. This is done by linear interpolation -- taking
fractional distances along the block based on the proportion of the address
range. So, for example: 150 ELM ST should be about half-way down
the block in the "100 block of Elm." Geocoding then creates a
POINT
FEATURE at that exact x,y location on the map and adds the point to
a NEW LAYER of points.
Establishing Geocoding Parameters
The street-lines theme must have street NAMES and ADDRESS RANGES in order
to perform the geocoding. The Set up wants us to identify the appropriate
fields in the attribute table for each required item. In our practice example:
-
Select the US STREETS addressing style.
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Specify the Address Range Variables in the Attribute Table:
In the Census TIGER files these are:
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Fraddl -- From Address Left (beginning street number on left side)
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Fraddr -- From Address Right
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Toaddl -- To Address Left (ending street number on left)
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Toaddr -- To Address Right
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Specify the Street Name Variable: Fename -- the Feature Name (street
name).
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Build Index | YES.
Adding an GEOCODE THEME (in ArcView -- some differences
are presumed)
-
Menu VIEW | GEOCODE ADDRESSES
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Confirm that YOUR ADDRESS FILE is the input file name.
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Select an "offset" from the street, if desired.
The GEOCODE EDITOR will appear automatically...
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Press the Batch-Match-Bar to Begin Processing. [Done when complete.]
Note
the number of Matches vs. Non-Matched Items.
-
Use INTERACTIVE RE-MATCH to view and possibly match those not matched.
-
Perhaps adjust sensitivity and spelling parameters in 'Properties' to increase
matched cases.
A new set of point features will be created. The point locations correspond
to a position INTERPOLATED along the street centerline (with
offset, if specified) between nodes based on the address range. You
may wish to edit the legend--symbol style, color or size--for the new layer.
Last Updated: February 2005