Calculating Bearing of a Polyline ArcGIS 10
This thread just solved a problem for me, so I thought I would comment on what I did to get the desired outcome, the same as what the original question is.
I tried the python script Chase Carter added earlier in this thread, worked perfectly for me, it provided the below columns in a feature class:
I did two things differently, the first being I ran it in the python command line, rather than making a toolbox tool. The reason being this will be a once off use, I dont see myself needing this tool very often.
The second thing I did was added a line to define the feature class I wanted the fields to be added to. the reason I did this was because I was not using a toolbox tool, but simply running command line.
So from Chase' code I deleted these two lines:
#Get evidence feature layer name out_feat_class = gp.GetParameterAsText(0)
Then I added a single line in the same spot I deleted the previous two lines from (approx line 26-27)
out_feat_class = r'Database Connections\GISADMIN@SDE_Spatial@Smithy.sde\SDE_SPATIAL.GISADMIN.Uploading_New_Data\SDE_SPATIAL.GISADMIN.Airport_ORC_Bearing_Lines'
So in summary, this is the entire code I ran to produce the two columns highlighted yellow above:
"""
Add fields of azimuths and bearings to a featurelayer of lines.
Azimuths can be based on map or geodgraphic coordinates.
For segmented lines, azimuths are length-weighted averages of segments.
"""
# Import system modules
import sys, string, os, math, random, traceback, tempfile
# Create the Geoprocessor object
#gp = win32com.client.Dispatch("esriGeoprocessing.GpDispatch.1")
import arcgisscripting
gp = arcgisscripting.create()
### Check out any necessary licenses
##gp.CheckOutExtension("spatial")
##
gp.OverwriteOutput = 1
# Load required toolboxes...
#gp.AddToolbox("C:/Program Files/ArcGIS/ArcToolbox/Toolboxes/Data Management Tools.tbx")
# Script arguments...
try:
#Get bearing type
geodesic = 'true' #gp.GetParameterAsText(1) == 'true'
#Get evidence feature layer name
out_feat_class = r'Database Connections\GISADMIN@SDE_Spatial@Smithy.sde\SDE_SPATIAL.GISADMIN.Uploading_New_Data\SDE_SPATIAL.GISADMIN.Airport_ORC_Bearing_Lines'
#gp.AddMessage(gp.describe(out_feat_class).shapetype)
if gp.describe(out_feat_class).shapetype != "Polyline":
raise Exception,'not a polyline-type feature class'
#Check for Azimuth field
fieldnames = []
fields = gp.ListFields(out_feat_class)
field = fields.next()
while field:
fieldnames.append(field.name)
field = fields.next()
if 'SDMBearing' not in fieldnames:
gp.addfield_management(out_feat_class,'SDMBearing','long',5)
if 'SDMAzimuth' not in fieldnames:
gp.addfield_management(out_feat_class,'SDMAzimuth','long',5)
#Open attribute table for update featureclass
outrows = gp.updatecursor(out_feat_class)
#Define the bearing, azimuth algorithm
def geodesic_azimuth(inshape):
""" Map azimuth calculation from a polyline shape """
sumazmlen = 0
sumbrglen = 0
sumlen = 0
line = inshape.getpart(0)
pnt = line.next()
if pnt:
pnt0 = pnt
pnt = line.next()
while pnt:
delx = pnt.X-pnt0.X
dely = pnt.Y-pnt0.Y
sdmazimuth = int(89.5-math.atan2(dely,delx)*180/math.pi)
if sdmazimuth < -90:
sdmbearing = sdmazimuth + 180
elif sdmazimuth > 90:
sdmbearing = sdmazimuth - 180
else:
sdmbearing = sdmazimuth
#gp.AddMessage(str((sdmbearing,sdmazimuth)))
# sumbrglen += sdmbearing*len
# sumazmlen += sdmazimuth*len
# sumlen += len
pnt0 = pnt
pnt = line.next()
# return [sumbrglen/sumlen,sumazmlen/sumlen]
return [sdmbearing,sdmazimuth]
#Process the lines
outrow = outrows.next()
while outrow:
if geodesic:
outshape = outrow.shape
[sdmbearing,sdmazimuth] = geodesic_azimuth(outshape)
#gp.AddMessage('!: %s,%s'%(sdmbearing,sdmazimuth))
outrow.sdmbearing = sdmbearing
outrow.sdmazimuth = sdmazimuth
else:
pass #map_azimuth(inrow.shape)
outrows.updaterow(outrow)
outrow = outrows.next()
#georow = georows.next()
except (Exception):
# get the traceback object
tb = sys.exc_info()[2]
# tbinfo contains the line number that the code failed on and the code from that line
tbinfo = traceback.format_tb(tb)[0]
# concatenate information together concerning the error into a message string
pymsg = "PYTHON ERRORS:\nTraceback Info:\n" + tbinfo + "\nError Info:\n " + \
str(sys.exc_type)+ ": " + str(sys.exc_value) + "\n"
# generate a message string for any geoprocessing tool errors
msgs = "GP ERRORS:\n" + gp.GetMessages(2) + "\n"
gp.AddError(msgs)
# return gp messages for use with a script tool
gp.AddError(pymsg)
# print messages for use in Python/PythonWin
print pymsg
print msgs
raise
