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Python error question

progis99

I am a beginner and just starting to learn how to use Python I learned from Python Scripting for Map Automation.

My question to you is that whenever I get an error I see the word Traceback or errors in highlight red in my python window.

My question to you is do I need to have a pythonWin installed ? My computer at work does not have it but I use the python Window inside ArcMap.

Are there site that can I read or learn about the Traceback error ? I am sure there are bunch of question that Traceback has in it.

So what does Traceback means and what does it do ?

Thanks

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progis99

One more other question. Which one should i write the code in the Pyscripter ? The python interpreter below or the top with the module ?Xander Bakker‌

progis99

Xander Bakker‌ ok, so for example, if you want to write one code and all of sudden it gave you the error in python window and then you turn to pyscripter and use the same one code and test it. Is that what you are suggesting ?

XanderBakker

Sometimes I use the python window to do something quick and dirty. You can also try things in the Python windows and copy and paste it into the editor of PyScripter to create something more enhanced. I do prefer coding directly in PyScripter since it is much easier to change things on lines written before, while in the Python window you write a single line, execute it and code the next line. I also execute the code directly from PyScripter (as do most people).

The other advantage of coding in and IDE like PyScripter is that your syntax is directly checked and you easily save what you are writing. When you create a script in PyScripter you can easily change hard coded variables into parameters and create a toolbox script that you can run in ArcMap and share with others. The other people don't need any coding experience, since they see a tool just like the ones provided by Esri.

progis99

I am trying to understand between the two Pyscripter and Python Window and how it works together.

So for the Pyscripter you just write to test it and if it works you copy and paste them to the Python Window but change to the functions or classes to Python window where they understand it and run from Python windows?

Or do I just write the code within the Pyscripter and run the code from there and will that change in ArcMap ?

Thanks

XanderBakker

Glad it worked. The r is for "Raw String Notation":

https://docs.python.org/3.3/library/re.html#raw-string-notation (sorry 3.3 docs)https://docs.python.org/3.3/library/re.html#raw-string-notation

If you copy and paste a path in python code it will probably be invalid since you have to use double backward slashed, forwards slashes or the r in front of the string holding the path. Normally the last option is the easiest,

progis99

I put that damn r into what you suggest and it worked ...

Is the "r" stand for reclusive , correct ?

XanderBakker

That shouldn't be a problem if you run the code from the Python Window inside ArcMap.

What happens if you place an r before "E:\State_mosaic\Elevations.gdb":

mxd.replaceWorkspaces("","NONE",r"E:\State_mosaic\Elevations.gdb","FILEGDB_WORKSPACE",True)

progis99

mxd = arcpy.mapping.MapDocument("CURRENT")

XanderBakker

How do you set you mxd variable?

progis99

Right now I am at work and here is the error i am having ....

>>> mxd.replaceWorkspaces("","NONE","E:\State_mosaic\Elevations.gdb","FILEGDB_WORKSPACE")

Runtime error

Traceback (most recent call last):

File "<string>", line 1, in <module>

File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\utils.py", line 181, in fn_

return fn(*args, **kw)

File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\_mapping.py", line 915, in replaceWorkspaces

return convertArcObjectToPythonObject(self._arc_object.replaceWorkspaces(*gp_fixargs((old_workspace_path, old_workspace_type, new_workspace_path, new_workspace_type, validate), True)))

ValueError: MapDocObject: Unexpected error

DanPatterson_Retired

Both are harmless although they need to make registry additions for which you may not have permissions to do. You will quickly find out if you can install either by yourself or need your Administer to do so.

progis99

the only problem is that my computer is under Government and it must be approve before I can use them. Does it have any issue ?

FranciscoGirón_Gesteira

If you are just beginning there is no need to install anything. Every Python installation includes IDLE, a simple grafical interface with many basic funtionalities including debugging, colorizing, auto-indentation, etc. Not as good as Pyscripter, but is already installed. I personally don't like Pythonwin. Just a thing, if using an external IDE, remember putting an "import arcpy" line at the start of every script you write.

If you are able to install Pyscripter set up the options to read arcpy help and perform code completion with it. Just add arcpy to the special packages line under code completion in IDE options.

The Traceback shows you the line of your code where an error occurred, and which kind of error it is. It should be more than enough in the beginning, forget about try/exception and others until you are writing your own scripts.

DanPatterson_Retired

the python docs are here why dont you install pythonwin and/or Pyscripter the Arc* ide is pretty useless

XanderBakker

It helps to "trace back" the line where the error occurred.

The documentation can be found here:

28.10. traceback — Print or retrieve a stack traceback — Python 2.7.9 documentation

And you should read this help topic: Error handling with Python

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