Latest Contributions by GerryGabrisch

I am testing a Python script where an ESRI shapefile is converted to a raster (based on FID).  The resulting raster is converted to ASCII for further processing.  Interestingly the tool worked great then started giving errors.  The source of the error is that the output ASCII file is now inserting extra spaces in the header of the ASCII file where earlier in the day it was not. Here is an example of the problematic ASCII output. ncols         17 nrows         41 xllcorner     1193433.4604796 yllcorner     659603.16649559 cellsize      10 NODATA_value  -9999 The column of numbers have extra spaces resulting in a left justified column of data when only one space should exist between the names (ncols, nrows...) and the data (17, 41). What would cause this behavior?  Am I stuck with using regular expressions to purge the extra white spaces?  try:     print "Split polygon by percent area from the top down..."     import sys, traceback, os     import arcpy          arcpy.env.overwriteOutput = True     ########################################################################################     #The Input Feature Class or projected data to Divide into Percents...     inFC = r"Z:\GISpublic\GerryG\PythonScripts\SplitPolygonByPercent\testData\testdata.shp"     #The rasterized version of the polygon...     outRas = r"Z:\GISpublic\GerryG\PythonScripts\SplitPolygonByPercent\outRas"     #The cell size of the outRas-smaller is better but takes longer to process..     outCellSize = 10     #Useer defined precent by area divisions...will split a polygons into 60%, 20%, and 20%     divisions = [60,25,15]     #ASCII version of the raster data....     outASCII = r"Z:\GISpublic\GerryG\PythonScripts\SplitPolygonByPercent\testdata.asc"     #ASCII version of the split by area data     splitASCII = r"Z:\GISpublic\GerryG\PythonScripts\SplitPolygonByPercent\Split.asc"     #The Output Raster....     FinalRaster = r"Z:\GISpublic\GerryG\PythonScripts\SplitPolygonByPercent\PercentArea"          ##########################################################################################          #Holds the total area of each percentage....     areaPercents = []     #Get the polygon area...     rows = arcpy.SearchCursor(inFC)     shapeName = arcpy.Describe(inFC).shapeFieldName     for row in rows:         feat = row.getValue(shapeName)         polygonArea = feat.area     #Calculate the areas for each percent division         for item in divisions:         areaPercents.append(polygonArea* item/100.0)         print "Converting polygon to ESRI GRID..."     arcpy.PolygonToRaster_conversion(inFC, "FID",outRas,"", "", outCellSize)     print "Converting ESRI GRID to ASCII..."     arcpy.RasterToASCII_conversion(outRas, outASCII)     print "Create the new ascii file"     fw = open(splitASCII, 'a')     #Keep track of the line number to ensure the header gets written correctly to     #the new .asc file     linecounter = 1     cell_area_counter = 0     thispercentcounter = 0     with open(outASCII, 'r') as f:         for line in f:             #The first 6 lines are header-just copy that over to the new asc file.             if linecounter <=6:                 fw.write(line)             #The remaining lines have data...convert them to percent values..             else:                 #Strip those pesky blank spaces at the start and ends of the line                 line = line.strip()                 linelist = line.split(" ")                 newlinelist = []                 for item in linelist:                     if item =="-9999":                         newlinelist.append(item)                     else:                         #thispercentcounter +=1                         cell_area_counter = cell_area_counter + (outCellSize*outCellSize)                         if cell_area_counter <areaPercents[thispercentcounter]:                             newlinelist.append(str(divisions[thispercentcounter]))                                                      else:                             thispercentcounter +=1                             cell_area_counter = 0                             print  thispercentcounter                             newlinelist.append(str(divisions[thispercentcounter]))                                              fw.write(" ".join(newlinelist)+"\n")             linecounter+=1     print "Creating output raster..."     arcpy.ASCIIToRaster_conversion(splitASCII,FinalRaster, "INTEGER")                    #Take out the trash....         os.remove(outASCII)     os.remove(splitASCII)     arcpy.Delete_management(outRas)                  print "Done" except:     print "error"     tb = sys.exc_info()[2]     tbinfo = traceback.format_tb(tb)[0]     pymsg = "PYTHON ERRORS:\nTraceback info:\n" + tbinfo + "\nError Info:\n" + str(sys.exc_info()[1])     print pymsg + "\n" ... View more

You learn something new every day in GIS. If I open a shapefile attribute table, select an attribute, and use the field calculator to populate the field with an expression such as... attributeX / 0 I get an error all calculated values were invalid, no rows were updated. But attributeX / attributeY returns no error even if values in attributeY have zero values, In fact, it populates those values with zero values. This is disturbing. If I do this same test in a geodatabase I get null values for the zero division rows. I understand that there are data structure limitations.   Shapefile fields are not nullable... but the shapefile example ought to give some warning! ... View more

I have a feature class of building footprints and a surface (LiDAR highest hit - LiDAR last return).  I am trying to use this surface to estimate the height of the buildings. Transferring the values from the raster to the polygons should be a straight forward operation using add surface information but that tool is useless and returns a 99999 error code. I tried the Zonal Statistics as a Table, then joined the table using the object ids.  I want to populate an existing field in the feature class with the mean value from the zonal statistics output but the field calculator (both within the attribute table and the Toolbox tool) populate the attribute with the objectID value.  This is odd behavior. Both data are in the same projection, UOM, datum.... I do not understand why this is happening.  Is this a know bug or a problem specific to my installation? Should I accept that I should export the join to a new FC and just clean up the e-trash later? ... View more