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I know that the purpose of the ArcPy GetParameterAsText function is to return parameters as text, but what is the benefit of doing that?

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  • How do you find the list of parameters? (from arcpy.GetParameterAsText(0)) I've inherited scripts from a predecessor that uses this a lot, and I need to be able to edit these parameters to provide new/different options in the dropdown that the user sees. I'm new to python, arcpy. Can read most of it and understand what's being asked, but I can not figure out where the parameters come from, to be able to update them as needed.
    – B Hendee
    May 20, 2022 at 14:52

2 Answers 2

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The summary on the Esri GetParameterAsText documentation states:

Gets the specified parameter as a text string by its index position from the list of parameters.

Functionally this allows you to pass arguments to a Python script tool. Script tools allow you to provide custom functionality in a GUI to those who do not want to use Python.

The documentation also provides an example of the usage:

import os
import arcpy

# Set the input workspace, get the feature class name to copy
#  and the output location.
arcpy.env.workspace = arcpy.GetParameterAsText(0)
in_featureclass = arcpy.GetParameterAsText(1)
out_workspace = arcpy.GetParameterAsText(2)

out_featureclass = os.path.join(out_workspace,
                                os.path.basename(in_featureclass))

# Copy feature class to output location
arcpy.CopyFeatures_management(in_featureclass, out_featureclass)
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  • so in this example the tool dialog box would have those three parameters that are prompting the user to input? Also, is the os.path.join trying to join different workspaces?
    – Ryan Mags
    Nov 22, 2019 at 4:54
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    Yes, the script tool dialogue box would have those three parameters which the user can input in the script tool. os.path.join() is combining the workspace path (e.g. /path/to/your/geodatabase.gdb) and the basename (e.g. some_name) to produce /path/to/your/geodatabase.gdb/some_name
    – Aaron
    Nov 22, 2019 at 4:58
4

In the ArcGIS Pro Help for arcpy.GetParameterAsText() its Summary is that it:

Gets the specified parameter as a text string by its index position from the list of parameters.

The way I think of it is that it is the means used to communicate, as text rather than objects, the choices made by an end user from the tool dialog that fronts a Python Script Tool of ArcPy.

The first parameter that the tool's author configures on its tool dialog is referenced from the script by using an index of 0 i.e. arcpy.GetParameterAsText(0).

There is an alternative way to reference the first parameter on the tool dialog, and that is as sys.argv[1] but that has limitations in the number of characters that it can accept whereas arcpy.GetParameterAsText() has no character limit. The two alternatives are documented in Accessing parameters in a script tool.

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