Select only streets that run north-south

ShannonGrumbly2

Is it possible to select streets based on their direction? I am actually missing the N or S prefix for my street names, so I cannot filter based on that criteria. I am hoping to select these streets to run a field calculator that enters the prefix direction. 

Any help would be greatly appreciated!

ChrisDonohue__GISP

In theory, if one has an Advanced license, one could do this:

1.  Use Feature Vertices to Points with the Both Ends option to create end points for each street.  Feature Vertices To Points—Data Management toolbox | ArcGIS Desktop 

2. Copy the Feature Class.

3.  Use Generate Near Table, using the original and the copy, and with the ANGLE option on

ArcGIS Help 10.1 

4.  Cull the data down in the resulting output table to the original end points and check the angle of matching points (the output will be a comparison of all points to all points, so will be many records, of which only a few are actually needed).

• I suspect some Spatial Joins will be needed here to keep the points correlated with the roads so one can eliminate the many unneeded angle results generated.  Alternatively, one could work out this process in Modelbuilder by Iterating just one street at a time so as to keep the confusion down.

• Also, note the angle directions comment from the Generate Near Table tool help:

A near angle measures from the x-axis (horizontal axis) to the direction of the line connecting an input feature to its nearest feature at their closest locations, and it is within the range of 0 to 180 or 0 to -180 decimal degrees - 0 to the east, 90 to the north, 180 (-180°) to the west, and -90 to the south.

In other words, the measuring starts at zero with East, then increases as one goes counter-clockwise to North, producing positive angles.  So North is 90 degrees, increasing to a maximum of 180 degrees at West.

Starting at East and heading to South (clockwise), the angle values are increasingly negative.  East is zero and South is -90, and West is at -180.

As a result, to query out North for your streets, try checking for an angle between 45 and 135.  For South, check  between -45 to -135.

Caveats:

This assumes the street data is set up in a way that allows checking of whole streets.  If a street is segmented out into multiple pieces, a Dissolve or other aggregation method may be needed to combine the pieces.

Also, I suspect there probably is a refined way to do all this in Python.  I'll leave suggestions on how to do that to the many Python guru's we have here on GeoNet.

Chris Donohue, GISP

EDIT:  cleaned up some wording for clarity