A few questions first:
- version of software, and do you have an Advanced (ArcInfo) license?
- are your transects all one segment, or several?,
- and if several, does the distance need to be split across the segments. For example, if first part is 450m and second is 550m, and your segments will be 1km (1000m) each, do you need the 5th segment to include 500m from the first, and 500m from the second
How I name my transect segments if, lets say the transect number i 101, the segments are 101.1, 101.2, 101.3. The next transect would be 102.1, 102.2, etc. We had a project that has transects that were 25-25k that I had to re-segment into 1k lengths to I could buffer. Because the flight line transect are over several segments (after removing "off-trans" segments), I had to create the transects as "routes" and use the geometry to product the exact length needed).
If they are all one segment, the process is much easier, including some ArcGIS tools or see this Feature Line Split
This probably will not run, as is (for one, you would have to supply the input attributes) and I would already have my segments sorted and converted to routes (I have 2 prior scripts that do that), but depending on how far along you are will determine if any of this will help.
EDIT: cleaned up the code a little...
'''
Purpose:
to re-segment the flown-and-cleaned transects into new segments, e.g. 1k
and then rerun the buffers.
Requirements for inputs:
- Sorted transect FC, with all attributes
(including TRANSNO, SEGMENT, VIEWSIDE, TransSeg (?), sortSegs, distFrom, distTo)
- Route FC created from the above based on TRANSNO, and two fields: distFrom, distTo
Input parameters for this script:
- workspace, i.e. the FGDB to read/write from
- sorted transects FC
- routes
- new segment distance
Outputs:
- temp files (overwritten for each segment):
- freq (frequency table)
- Points (the points used for splitting)
- zTransExp (the individual exported sorted trans)
- zTransSplit (the individual split transects)
- zTranFinal (last individual FC before append)
- reSegment<newLength> (final, all transects appended)
'''
import os, sys
import time
import arcpy
def myMsgs(message):
arcpy.AddMessage(message)
print(message)
myMsgs("Running against: {}".format(sys.version))
def main():
'''
Main function to resegment (retrofit) the flown transect to new segment length
'''
arcpy.env.overwriteOutput = True
theScriptPath = arcpy.GetParameterAsText(0)
if not theScriptPath:
theScriptPath = r"\_data\_scripts"
theTemplatePath = os.path.join(theScriptPath,"Reports\RetroFit\ReSegment.gdb")
theProjectDir = arcpy.GetParameterAsText(1)
if not theProjectDir:
theProjectDir = r"\_data\_ProjectName"
else:
myMsgs(theProjectDir)
theProjectDir = os.path.realpath(theProjectDir)
fdrReports = os.path.join(theProjectDir, "Reports")
fdrRetroFit = arcpy.GetParameterAsText(6)
if not fdrRetroFit:
fdrRetroFit = "RetroFit"
else:
myMsgs(fdrRetroFit)
fdrRetroFit = os.path.join(fdrReports, fdrRetroFit)
outFGDB = os.path.join(fdrRetroFit, "ReSegment.gdb")
arcpy.env.workspace = outFGDB
inputSort = arcpy.GetParameterAsText(2)
if not inputSort:
inputSort = "transSorted"
inputRoutes = arcpy.GetParameterAsText(3)
if not inputRoutes:
inputRoutes = "transRoutes"
newLength = arcpy.GetParameter(4)
if not newLength:
newLength = 1000
newLength= int(newLength)
thePts = "Point"
finalFC = "reSegA" + str(newLength)
if arcpy.Exists(finalFC):
myMsgs("deleting " + finalFC)
arcpy.Delete_management(finalFC)
if arcpy.Exists(finalFC):
myMsgs("still exists")
else:
myMsgs("doesnt exist")
spatialRef = arcpy.SpatialReference(3338)
myMsgs(" Creating/replacing the final FC: " + finalFC)
myMsgs(theTemplatePath)
sCur = arcpy.da.SearchCursor(inputRoutes, ["TRANSNO", "SHAPE@"])
for aRoute in sCur:
pointList = []
theTransID = aRoute[0]
geo = aRoute[1]
lenTrans = geo.length
myMsgs("-->> ReSegmenting {0}".format(theTransID) +
"; total initial length: " + str(int(lenTrans)) + "
calcSegs = int(lenTrans/newLength)
lastSeg = lenTrans - (newLength * calcSegs)
startPtDist = 0
newSeg = 0
if lastSeg < (newLength/2):
calcSegs = calcSegs - 1
while newSeg < calcSegs:
startPtDist = startPtDist + newLength
newPT = geo.positionAlongLine(startPtDist)
pointList.append(newPT)
newSeg = newSeg + 1
arcpy.CopyFeatures_management(pointList, thePts)
arcpy.AddField_management(thePts, "ptID", "SHORT")
arcpy.CalculateField_management(thePts,"ptID","!OBJECTID!","PYTHON_9.3","
'''
Done creating the list of points to be used for splitting
'''
exprTran = arcpy.AddFieldDelimiters(inputSort, "TRANSNO") + " = " + "'%s'" %theTransID
zTransExp = "in_memory/zTransExp"
arcpy.Select_analysis(inputSort, zTransExp, exprTran)
lstFieldsToDelete = "LENGTH;LATITUDE;LONGITUDE;XCOORD;YCOORD;PLANEDIST;TRANDIST;STARTTIME;ENDTIME;LENGTH_meters"
arcpy.DeleteField_management(zTransExp,lstFieldsToDelete)
zTransSplit = "in_memory/zTransSplit"
arcpy.SplitLineAtPoint_management(zTransExp,thePts, zTransSplit,"5 Meters")
arcpy.AddField_management(zTransSplit, "tmpSortID", "SHORT")
freqFC = "freq"
arcpy.Frequency_analysis(zTransSplit, freqFC, "tmpSortID")
sCur = arcpy.da.SearchCursor(freqFC, ["tmpSortID"])
for aRec in sCur:
freqSort = aRec[0]
cntSegs = 0
uCur = arcpy.da.UpdateCursor(zTransSplit, ["tmpSortID", "SHAPE@"])
for row in uCur:
geo = row[1]
firstPt = geo.firstPoint
firstPtX = int(firstPt.X)
firstPtY = int(firstPt.Y)
sCur = arcpy.da.SearchCursor(thePts, ["ptID", "SHAPE@"])
for rowPt in sCur:
geoPt = rowPt[1]
aPt = geoPt.firstPoint
aPtX = int(aPt.X)
aPtY = int(aPt.Y)
theID = rowPt[0]
if cntSegs == 0:
theNewPtID = 0
elif ((firstPtX == aPtX) and (firstPtY == aPtY)):
theNewPtID = theID
cntSegs = cntSegs + 1
row[0] = theNewPtID
uCur.updateRow(row)
theTranFinal = "zTranFinal"
arcpy.Sort_management(zTransSplit,theTranFinal,"sortSegs ASCENDING;tmpSortID ASCENDING","UR")
'''
IF ALL SEGS IN PROPER ORDER, will assign the new numbers and related numbers
'''
arcpy.AddField_management(theTranFinal,"finalSortID", "DOUBLE","3","1","
newSegID = 1.1
prevLength = 0
currLength = 0
uCursor = arcpy.da.UpdateCursor(theTranFinal, ["finalSortID", "SHAPE@"])
for aRow in uCursor:
currLength = aRow[1].length
if currLength < (newLength - 1):
aRow[0] = newSegID
newSegID = (newSegID + .1)
prevLength = currLength + prevLength
if prevLength > (newLength - 1):
newSegID = (int(newSegID) + 1.1)
prevLength = 0
else:
aRow[0] = newSegID
newSegID = (int(newSegID) + 1.1)
prevLength = 0
uCursor.updateRow(aRow)
arcpy.AddField_management(theTranFinal, "finalSortInt", "SHORT")
arcpy.CalculateField_management(theTranFinal,"finalSortInt","int(!finalSortID!)","PYTHON_9.3","
if not arcpy.Exists(finalFC):
arcpy.CreateFeatureclass_management(outFGDB, finalFC, "POLYLINE",theTranFinal, "SAME_AS_TEMPLATE", "SAME_AS_TEMPLATE", spatialRef)
myMsgs(" ...Appending to " + finalFC + "
arcpy.Append_management(theTranFinal, finalFC, "TEST", "
arcpy.AddField_management(finalFC, "newUniqID", "SHORT", 6, 0, 6)
arcpy.CalculateField_management(finalFC, "newUniqID", "!OBJECTID!","PYTHON_9.3","
lstFieldsToDelete = "sortSegs;distFrom;distTo;tmpSortID"
arcpy.DeleteField_management(finalFC,lstFieldsToDelete)
myMsgs(" Done deleting fields bogus fields")
myMsgs(" Creating a Feature Layer and adding it to the TOC")
fullFinalPath = os.path.join(outFGDB, finalFC)
arcpy.SetParameterAsText(5, fullFinalPath)
myMsgs('!!! Success !!!')
if __name__ == '__main__':
main()
If you look at the UpdateCursor area, you can see that I am working with the first and last point of the segments. It is just as easy to grab mid point geometry.
UpdateCursor—Help | ArcGIS for Desktop
Geometry—Help | ArcGIS for Desktop
I you have code you want to post, make sure it is formatted correctly. To add to a comment here, at the menu at the top, .... More > Syntax Highlighter > Python then paste you code in the box.
Hope this helps.
