Latest Contributions by SylviaNiderla

you were right! how obvious, guess thats why you shouldn't script late at night! thanks a lot. ... View more

ah I put that row.setValue("Cnt") in there - really I want something like the output of the previous function e.g row.setValue("Cnt",distance) but that doesn't work either. the nearpoint - 1 works when I run the script in a python window - its taking away the distance of points from a point (I think?). ... View more

Ok I have it now by NAMING the fields. Also it wouldn't work with the brackets so it works like this     rows = arcpy.UpdateCursor(infc)     for row in rows:         if row.getValue("Texture") == "Sandy" and row.getValue ("Humus") <= "10": #1-10 also doest not work             row.setValue("Richness", "poor")         else:             row.setValue("Richness", "none")         rows.updateRow(row)     del rows, row     arcpy.AddMessage("Completed") *edit - nm I got it. ... View more

ok, apparently I don't need the searchupdate curser bit. Anyway, I just want it to work for one field atm and then I will work out if it can work with numbers. But even that won't work, its something to do with the if/then statement, because I can copy one field to the other using the following code rows = arcpy.UpdateCursor(infc) for row in rows:   val = row.getValue (datafld)   row.setValue(outfld,val)   rows.updateRow(row) del rows but when I start using if/else statements It errors.     rows = arcpy.UpdateCursor(infc)     for row in rows:         if (row.getValue(inField1) == "Sandy"):             row.setValue(outField, "poor")         else:             row.setValue(outField, "none")         rows.updateRow(row)         del rows         arcpy.AddMessage("Completed") ... View more

ah, thanks. But now I just get an "unexpected error" so something in my "try" isn't right I guess. ok I know its the searchcurser bit try: rows = arcpy.SearchCursor(infc) for row in rows:         infc = row.getValue(inField1) + row.getValue(inField2) del rows how do I get my curser to read over the two fields I want to use in the next bit? ... View more

well I just couldn't get it to work, so I tried writing it this way. But this way nothing happens also even though it runs fine. Any ideas? import sys, arcpy try: infc = arcpy.GetParameterAsText(0)   # Input feature class inField1 = arcpy.GetParameterAsText(1)  # Input data field inField2 = arcpy.GetParameterAsText(2) outfld = arcpy.GetParameterAsText(3)  # Output result field except: arcpy.AddError("Cannot parse input arguments") sys.exit("Error reading arguments!") arcpy.AddMessage("Calculating field...")   try:         rows = arcpy.UpdateCursor(infc)         for row in rows: # iterate over the rows   if (row.getValue(inField1) == "Sandy") and (row.getValue(inField2) == "0-10"):    row.setValue(outField, "poor")   elif (row.getValue(inField1) == "Sandy") and (row.getValue(inField2) == ">10"):    row.setValue(outField, "medium")   else:    row.setValue(outField, "none")   rows.updateRow(row)   del rows   arcpy.AddMessage("Completed") except: errMsg = arcpy.GetMessages(2) arcpy.AddError("Unexpected error : " + errMsg) ... View more

OK, I'll try to explain fully - sorry if you already know some of this stuff... Essentially you can use Python to code in two ways. The first is just plain scripting, i.e.: do this if that     then do this else     do this then do this The code starts at the top of the file, then goes through line by line, does whatever it is told to do then proceeds to the next line. My first post the other day contained a script. It got the input from the user (or defaulted to something), did the calculation, then told the user it was done. More advanced Python programming makes use of Modules (anything following a def statement is a module). Modules are sometimes also called functions. These allow you to use the same bit of code more than once. For example, if I have a code that selects by attributes, performs a buffer then exports the data, and I want to do it three times while varying a few things, I could do (just making stuff up to explain the example, this code will definitely not run): inGDB = 'C:\data.gdb' inFeatureClass = 'input' # select field = 3, buffer by 5m, export to test_[fieldVal]_[buffersize] Featureclass in input GDB selection = arcpy.selectByAttributes(inGDB + '\\' + inFeatureClass, 'field = 3') bufferedSelection = arcpy.Buffer(selection,'5m') arcpy.Export(bufferedSelection, inGDB + '\\' + 'test_3_5m') # select field = 7, buffer by 7m, export to test_[fieldVal]_[buffersize] Featureclass in input GDB selection = arcpy.selectByAttributes(inGDB + '\\' + inFeatureClass, 'field = 7') bufferedSelection = arcpy.Buffer(selection,'7m') arcpy.Export(bufferedSelection, inGDB + '\\' + 'test_7_7m') # select field = 9, buffer by 1m, export to test_[fieldVal]_[buffersize] Featureclass in input GDB selection = arcpy.selectByAttributes(inGDB + '\\' + inFeatureClass, 'field = 9') bufferedSelection = arcpy.Buffer(selection,'1m') arcpy.Export(bufferedSelection, inGDB + '\\' + 'test_9_1m') Now, as I am repeating a lot of code, it would be simpler to define a module that takes the things that actually change as inputs and then does the operations. This module must be placed before it is called, so that it is loaded into memory. Adding the module gives: # inputs inGDB = 'C:\data.gdb' inFeatureClass = 'input' # define module (before trying to use it) def selectBufferExport(GDB, FC, fieldName fieldVal, buffersize):     '''selects FC (within GDB) entries for fieldName == fieldVal     buffers by buffersize     exports to new featureclass in GDB with name "test_fieldVal_buffersize"     '''     selection = arcpy.selectByAttributes(GDB + '\\' + FC, '%s = %s' % (fieldName, fieldVal))     bufferedSelection = arcpy.Buffer(selection, buffersize)     arcpy.Export(bufferedSelection, GDB + '\\' + 'test_%s_%s' % (fieldVal, buffersize)) # now call the module, passing it the variables selectBufferExport(inGDB, inFeatureClass, 3, '5m') selectBufferExport(inGDB, inFeatureClass, 7, '7m') selectBufferExport(inGDB, inFeatureClass, 9, '1m') # or, getting fancy, replacing the last four lines with a for loop: for (fieldval,buffer) in [(3, '5m'), (7, '7m'), (9, '1m')]:     selectBufferExport(inGDB, inFeatureClass, fieldVal, buffer) Not only have we saved a bunch of lines, but if we want to make changes to the method or add a step, we only have to change it in one place. Now that I have created this module I can use it as above, or I can call it from other scripts by importing the *.py file it lives in; if it was saved as selBuffExp.py I could import it into another script within the same folder and call the module with: import selBuffExp selBuffExp.selectBufferExport('test.gdb', 'test', 3, '5m') Now, when you import a file it actually runs/loads into memory the contents of the file. if __name__ == "__main__": is a statement that only runs if you are running the script by itself (i.e. from the command line, or as an Arc tool). However, when the file is imported its name is not "__main__", and that bit doesn't get run... If you don't have it, and you try to import it, it will load the module into memory and do all the things within the script (which at least makes a mess, but probably crashes if your paths aren't still valid or both are set to the same paths). Presumably you are making a script tool (not using it in a Field Calculator)? If you are making a script tool, the reason your code doesn't run is that you don't have the contents of the if __name__ == "__main__": part, so the module is never actually called. Arc tells you it is complete, meaning that the tool completed, but all you have given it to do is load something into memory (you haven't called the module or anything)... I modified the code from my first post to follow this convention as the original poster had used it; chances are you don't need to bother about it. If you aren't going to be importing it, you could just delete the if __name__ == "__main__": line and un-indent what was in there. I meant to reply I get an error if I include the "main" etc bit. <type 'exceptions.UnboundLocalError'>: local variable 'row' referenced before assignment Failed to execute (Script). I just can't work it out. I've copied everything and checked it in pythonwin using script checker. ... View more

Hi, I just happened to need the exact same thing as this post. However what is the if__name etc part for? When I use just this part (with my input/output fields set as parameters) import arcpy def customUpdateCursor(FeatureClass, inField1, inField2, outField): '''customUpdateCursor(FeatureClass, inField1, inField2, outField) takes a feature class and three field names; two for input fields to the calculation and one for output performs a conditional assesment on the inputs and returns a value to the output ''' rows = arcpy.UpdateCursor(FeatureClass) for row in rows: # iterate over the rows   if (row.getValue(inField1) == "Sandy") and (row.getValue(inField2) == "0-10"):    row.setValue(outField, "poor")   elif (row.getValue(inField1) == "Sandy") and (row.getValue(inField2) == ">10"):    row.setValue(outField, "medium")   else:    row.setValue(outField, "none")   rows.updateRow(row) del row, rows # End of customUpdateCursor function it says completed, but it doesn't update my "Richness" field. Any idea? Do i need a searchcurser too? ... View more

Hi, no I was just trying to add a join (i.e join an attribute table to another). I got it working, by going through my model really really carefully. It still has a few issues though. I found a lot of the time a join wouldnt work if I just dragged a layer from my map or used the drop down selection, rather than navigating to it using the folder method. Also the feature class was created from another layer so it was a selection of that layer. Maybe I used the wrong name for it. ... View more

actually now I'm stuck with joins. I can't seem to join a shapefile to a newly created feature class. I've created the feature class several different ways but there it won't allow it as an input table. I am able to join the feature class to the shapefile, but I need it the other way around. ... View more