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I like to create a table with open() in a loop using the SearchCursor and InsertCursor, but I don't know how. Before I used a few geoprocessing tools to get a field for percent. The Attributtable of the raster looks like this

enter image description here

So I need to write the field percent with the value 8 in a new table to get a result which looks like this:

enter image description here

This is where I'm working on with ArcMap10.2.1:

import arcpy
import os
from arcpy import env

env.overwriteOutput = True
env.workspace = r"D:\Julia_T\projekt\testdataA"

#folder to list
ascFileList = arcpy.ListFiles("*.asc")

print ascFileList
#works
for ascFile in ascFileList:
# geoprocessing steps
ascFileName = os.path.splitext (ascFile)[0]
print ascFileName
#works
rastFile = ascFileName + "_output.img"
print rastFile
#works
#run the tool
arcpy.ASCIIToRaster_conversion (env.workspace + "\\" + ascFile, env.workspace + "\\" + rastFile, "INTEGER")

# Process: Projektion definieren
arcpy.DefineProjection_management (env.workspace + "\\" + rastFile, "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]")
# Process: Feld hinzufügen
arcpy.AddField_management (env.workspace + "\\" + rastFile,"Prozent","DOUBLE")
# Process: Feld berechnen
arcpy.CalculateField_management(env.workspace + "\\" + rastFile,"Prozent","( [Count] /53959) *100", "VB")
#tabelle bauen
with arcpy.da.SearchCursor(env.workspace + "\\" + rastFile,["Value","Prozent"],""""Value" = 8""") as sCur:
    outputfile = r"D:\Julia_T\output\output.txt"
    with arcpy.da.InsertCursor(outputfile,["Value","Prozent"]) as iCur:
               for row in sCur:
                print row [0], row [1]
                f = open (outputfile, 'w')
                f.write ("Value\nProzent")
                f.close()

How can I get the percent from the value 8 in a new table?

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  • Are you opening and closing the file inside the for loop, or is that an indentation error? Commented Jul 28, 2014 at 13:40

2 Answers 2

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4

An InsertCursor can write to a Table, your text file is not a Table! Also you create iCur but never actually do anything with it...

Try this code:

outputfile = r"D:\Julia_T\output\output.txt"
f = open (outputfile, 'w')
f.write ("Value,Prozent")
with arcpy.da.SearchCursor(env.workspace + "\\" + rastFile,["Value","Prozent"],""""Value" = 8""") as sCur:
    for row in sCur:
        print row [0], row [1]            
        f.write(str(row[0]) + "," + str(row[1]) + "\n")
f.close()
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4
  • Yes my code doesn’t look well. I tried it yesterday a few hours and deleted a few lines of the code while getting nervous. Anyway, thanks a lot for your help. It works but the code gives just the values from the last file from the list back. So I think it overwrites the other results from the searchCursor. Do I have to use something like a next operation? Commented Jul 29, 2014 at 6:55
  • I have tweaked the code slightly have a look at it now but your cursor has a whereclause of Value = 8 so this will only every return a single row from the raster. Your original uploaded code appears to have lost its indentation so it's at all clear what the loop structure is. Commented Jul 29, 2014 at 8:51
  • So I have to export the attribute table with the values (see the picture in the question) first and loop than through each attribute table with the searchCoursor in a new script by creating a new List? The whereclause of Value = 8 is just to create a new table with just the percent of the value 8 At the moment the code givs me this back: Value,Prozent,8,94.1010767435 Commented Jul 29, 2014 at 9:23
  • Perhaps this is my solution: outputpath = r"D:\Julia_T\output" outname = rastFile + "table.dbf" arcpy.TableToTable_conversion(env.workspace + "\\" + rastFile, outputpath, outname) And than I have to continue in a new script. Commented Jul 29, 2014 at 10:04
0

At the end the script is working with writing one open-operation at the front of the script and one at the end. The one at the end has to have a open(xxx.txt, 'a'): 

import arcpy
import os
from arcpy import env

env.overwriteOutput = True
env.workspace = r"D:\Julia_T\projekt\testdataA"

#folder to list
ascFileList = arcpy.ListFiles("*.asc")

print ascFileList

outputfile = r"D:\Julia_T\output\output.txt"
f = open (outputfile, 'w')
f.write ("Value,Prozent,\n")
f.close()
#works
for ascFile in ascFileList:
# geoprocessing steps
ascFileName = os.path.splitext (ascFile)[0]
print ascFileName
#works
rastFile = ascFileName + "_output.img"
print rastFile
#works
#run the tool
arcpy.ASCIIToRaster_conversion (env.workspace + "\\" + ascFile, env.workspace + "\\" + rastFile, "INTEGER")

# Process: Projektion definieren
arcpy.DefineProjection_management (env.workspace + "\\" + rastFile, "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]")
# Process: Feld hinzufügen
arcpy.AddField_management (env.workspace + "\\" + rastFile,"Prozent","DOUBLE")
# Process: Feld berechnen
arcpy.CalculateField_management(env.workspace + "\\" + rastFile,"Prozent","( [Count] /53959) *100", "VB")
#start table

f = open (outputfile, 'a')
with arcpy.da.SearchCursor(env.workspace + "\\" + rastFile,["Value","Prozent"],""""Value" = 8""") as sCur:
    for row in sCur:
        print row [0], row [1]
        f.write(str(row[0]) + "," + str(row[1]) + "\n")
f.close()

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