I am writing code to iterate thru each feature in a polygon feature class and use the selected feature to clip a roads layer and calculate length. The data from the polygon feature class, and the length of the roads for each polygon is output to a CSV file. The code is working except for the arcpy.SelectLayerByAttribute_management line (line 173). This seems to break my code and I am have troubles figuring out why or coming up with a reasonable solution. Any help is greatly appreciated.
# -*- coding: utf-8 -*-
# ---------------------------------------------------------------------------
# 2_TrapStatsAndFloatingRoadDensity.py
# Created on: 2015-4-8 1:30 pm
# Completed on: 2015-4-9
# Created by: L.M.Blackburn
# ArcGIS 10.1
# Notes: iterates thru orders shapefiles and creates a buffer
# around each point. The round buffer is converted to a feature envelope
# which makes a square polygon around the point. This square is used to
# clip the roads layer. Then I calculate length for the clipped roads by adding
# a field and calculating geometry. Run statistics to get the sum length
# of roads in each square. export sum length, block name, centroid of
# square out to a text file
# (2nd script for 4th part of analysis)
# Needed data: Order sublayer from VRP
# List of fields to drop
# Roads network to get length data
# ---------------------------------------------------------------------------
# Import arcpy module
import arcpy, os, sys, traceback, csv
# Set the necessary product code
import arceditor
import arcinfo
# Set workspace environment - this is where the solved route layers are located
arcpy.env.workspace = 'F:\\Workspace\\Sandy\\GM_costAnalysis\\analysis2\\OrdersProjected\\'
# --------------------Set local variables ------------------
# ---workspace for order layers
ordersLyr = 'F:\\Workspace\\Sandy\\GM_costAnalysis\\analysis2\\OrdersProjected\\'
# ---workspace for buffer layers
bufferLyr = 'F:\\Workspace\\Sandy\\GM_costAnalysis\\analysis2\\Buffers\\'
# ---set default buffer distance
bufDefault = "6000 Meters"
# ---workspace for envelope layers
envelopeLyr = 'F:\\Workspace\\Sandy\\GM_costAnalysis\\analysis2\\Envelopes\\'
# ---set workspace path for clipped roads
outDataPath = 'F:\\Workspace\\Sandy\\GM_costAnalysis\\analysis2\\ClipRoads\\'
# ---set road layer - for use in clip & length
Road = 'F:\\Workspace\\Sandy\\GM_costAnalysis\\RoadsForSnap\\SDC Edge Source.shp'
# ---fields to delete from Orders layers
dropFields = ["Descriptio", "ServiceTim", "TimeWind_1", "TimeWind_2", "TimeWind_3", "TimeWindow", "MaxViolati", "MaxViola_1", \
"PickupQuan", "DeliveryQu", "Revenue", "SpecialtyN", "Assignment", "RouteName", "ViolatedCo", "CumulTrave", \
"CumulDista", "CumulTime", "ArriveCurb", "DepartCurb", "DepartTime", "WaitTime", "ViolationT", "CumulWaitT", \
"CumulViola", "ArriveTime", "SourceID", "SourceOID", "PosAlong", "SideOfEdge", "CurbApproa", "Status"]
try:
# Step 1 - loop through each route layer and do the following processes
print 'Opening CSV file...'
# Create table for output data
# Needed fields: From script [Block, Scale, Sequence, FromPrevTr, FromPrevDi, totTime, totDist, x, y, totalRdLength]
CSVFile = 'F:\\Workspace\\Sandy\\GM_costAnalysis\\analysis2\\AllTrapsData.csv'
f = open (CSVFile, "wb")
w = csv.writer(f, delimiter=',', lineterminator='\n')
fieldNames = ['Block', 'Scale', 'Sequence', 'FromPrevTr', 'FromPrevDi', 'x', 'y', 'bufferDist','totTime', \
'totDist', 'totalRdLength', '\n']
w.writerow(fieldNames)
# Step 2 - Loop through route layers and export Order sublayers to orders folder
# Create variable to hold layer files
orderList = arcpy.ListFiles("*.shp")
# Loop through layers & break name into segments to be used when naming orders lyrs
print 'Creating Buffers...'
for shp in orderList:
lyrs = arcpy.mapping.Layer(ordersLyr + shp)
splitName =shp.split('_')
block = splitName[0]
scale = splitName[1].rstrip('.shp')
# define buffer distance - double check the buffer distances w/ Sandy (I may need to double these values)
if scale == "1K":
bufDist = "500 Meters"
elif scale == "2K":
bufDist = "1000 Meters"
elif scale == "3K":
bufDist = "1500 Meters"
elif scale == "4K":
bufDist = "2000 Meters"
elif scale == "6K":
bufDist = "3000 Meters"
elif scale == "500":
bufDist = "250 Meters"
else:
bufDist = bufDefault
print 'Order: ' + shp + ', Buffer: ' + bufDist
# Jump into orderLayers to delete unneeded fields & add XY
arcpy.DeleteField_management(shp, dropFields)
arcpy.AddXY_management(shp)
# Step 4 - Run buffer on order layers
arcpy.Buffer_analysis(shp, bufferLyr + 'buf' + '_' + block + '_' + scale, bufDist, 'FULL', 'ROUND', 'NONE', '#')
arcpy.Buffer_analysis(shp, bufferLyr + 'buf2' + '_' + block + '_' + scale, bufDefault, 'FULL', 'ROUND', 'NONE', '#')
bufferList = []
for dpath, dnames, fnames in arcpy.da.Walk(bufferLyr, datatype = 'FeatureClass', type = 'Polygon'):
for files in fnames:
bufferList.append(os.path.join(files))
# Step 5 - Run feature envelope to polygon on buffer layers
print 'Converting round buffers to squares...'
for bufShp in bufferList:
bufSplitName = bufShp.split('_')
blockID = bufSplitName[1]
scaleID = bufSplitName[2].rstrip('.shp')
bufID = bufSplitName[0]
print 'Buffer: ' + bufShp + ' Block: ' + blockID + ' Scale: ' + scaleID + ' BufferType: ' + bufID
arcpy.FeatureEnvelopeToPolygon_management(bufferLyr + bufShp, envelopeLyr + bufID + '_' + blockID + '_' + scaleID, 'SINGLEPART')
# Step 6 - Calculate totalTime and totalDistance using insert cursor
# loop through each record in the table - calculate values and...
# use selected features to clip roads layer & calculate geometry
# add values to the CSV table
print 'Populating CSV file...'
envelopeList = []
for dirpath, dirnames, filenames in arcpy.da.Walk(envelopeLyr, datatype = 'FeatureClass', type = 'Polygon'):
for filename in filenames:
envelopeList.append(os.path.join(filename))
for eLayer in envelopeList:
dataList = []
eLayerName = eLayer.split('_')
blockEID = eLayerName[1]
scaleEID = eLayerName[2].rstrip('.shp')
bufEID = eLayerName[0]
dataList.append(str(blockEID))
dataList.append(str(scaleEID))
print 'eLayer: ' + eLayer + ' Block: ' + blockEID + ' Scale: ' + scaleEID + ' BufferType: ' + bufEID
eLyrPath = envelopeLyr + eLayer
#Make a layer from the feature class - needed for selecting records to be used in the clipping
arcpy.MakeFeatureLayer_management(eLyrPath, "clipLayer")
# use search cursor to grab data row by row
with arcpy.da.SearchCursor(eLyrPath, ("Sequence", "FromPrevTr", "FromPrevDi", "POINT_X", "POINT_Y",
"BUFF_DIST")) as cursor:
for row in cursor:
dataList.append(str(row[0]))
dataList.append(str(row[1]))
dataList.append(str(row[2]))
dataList.append(str(row[3]))
dataList.append(str(row[4]))
dataList.append(str(row[5]))
n = int(row[0])
n2 = n +1
sel = "=" + str(n2)
prevTime = float(row[1])
prevDist = float(row[2])
# rQuery = '"Sequence" = \''+ n +'\'' ---this line throws errors---
expression = arcpy.AddFieldDelimiters(eLyrPath, "Sequence")+ sel
qrow = arcpy.SearchCursor(eLyrPath, where_clause=expression, fields = "FromPrevTr; FromPrevDi")
row2 = qrow.next()
while row2:
postTime = row2.getValue("FromPrevTr")
# print postTime
totTime = prevTime + float(postTime)
# print totTime
dataList.append(str(totTime))
postDist = row2.getValue("FromPrevDi")
# print postDist
totDist = prevDist + float(postDist)
# print totDist
dataList.append(str(totDist))
row2 = qrow.next()
# select single record to use when clipping
# 4/9/15 - having issues with this line
arcpy.SelectLayerByAttribute_management("clipLayer", "NEW_SELECTION", '"Sequence" = \''+ n +'\'')
# Clip roads w/ selected polygon - for this I will need a search cursor
clipRoads = outDataPath + 'rdsClip_' + blockEID + '_' + scaleEID + '_' + bufEID + '_' + str(n)
arcpy.Clip_analysis(Road, "clipLayer", clipRoads)
clipRoadsShp = clipRoads + ".shp"
# Use geometry/length to get the total length of clipped roads(in meters)
g = arcpy.Geometry()
geometryList = arcpy.CopyFeatures_management(clipRoadsShp, g)
length = 0
for geometry in geometryList:
length +=geometry.length
# append length (meters) at end of line to csv dataList
dataList.append(str(length))
# print length
# Write dataList to csv file ---- may need to dedent this one more time ---
w.writerow(dataList)
# print dataList
print 'Script complete'
f.close()
except:
if arcpy.Exists(CSVFile):
w.writerow(dataList)
print 'Data written in CSV file'
f.close()
print 'Program failed.'
print 'Check python errors.'
tb = sys.exc_info()[2]
tbinfo = traceback.format_tb(tb)[0]
pymsg = "PYTHON ERRORS:\nTraceback Info:\n" + tbinfo + "\nError Info:\n " + str(sys.exc_type) + ": " + str(sys.exc_value) + "\n"
msgs = "ARCPY ERRORS:\n" + arcpy.GetMessages(2) + "\n"
arcpy.AddError(msgs)
arcpy.AddError(pymsg)
print msgs
print pymsg
arcpy.AddMessage(arcpy.GetMessages(1))
print arcpy.GetMessages(1)
# print ("Points to select: {0}, Radius: {1}".format(centroidPath, radius))
