jamessample

gp.Describe fails on second iteration of loop

Discussion created by jamessample on Dec 8, 2010
Latest reply on Apr 5, 2011 by steveattt
  • Comment • 5
Hi all,

I'm having some problems with the gp.Describe method in 9.3.1 and Python 2.5. If anyone can help I'd appreciate it.

I have a folder called "Timeseries_All" which contains sub-folders called "1961", "1962" etc. Each of these folders contains 12 ESRI grids named "rain_year_month" (e.g. rain_1961_7 etc.). I want to get the no-data values for each of these rasters. My simple test code is as follows:

# Import modules
import arcgisscripting, os

# Create geoprocessor
gp = arcgisscripting.create(9.3)

# Set timeseries folder
tsFolder = "D:\Timeseries_All"

for year in range (1961, 1991):
    for month in range(1, 13):
        # Path to raster
        path = os.path.join(tsFolder, str(year), 'rain_' + str(year) + '_' + str(month))

        # Describe and return no-data value
        noDatVal = gp.Describe(path).NoDataValue

        # Print the result
        print noDatVal


This works correctly for the first iteration of the loop and returns the no data value of rain_1961_1 (which is -32768). I get an error on the second iteration, though:

>>> -32768
Traceback (most recent call last):
  File "C:\Python25\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 325, in RunScript
    exec codeObject in __main__.__dict__
  File "D:\James_S\Sarah_Tarland_Burn\Python\NoDataTest.py", line 14, in <module>
    rnNoData = gp.Describe(rnMon).NoDataValue
RuntimeError: DescribeData: Get attribute NoDataValue does not exist


The second dataset is not corrupt: I get the same message regardless of where I start in my data and all of my datasets appear to be fine. Anyone have any suggestions?

Thanks!

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