Python Toolbox input parameter list: how to split name from group name?

[Manu]

I enabled multiple value input for some parameter in an ArcMap 10.8 Python Toolbox.

In my script, I can easily split the input received from the UI by applying .split(";") since the input values are separated by ";".

However, when the user selects a layer from the drop-down that is located within a group, each such value consists of the group name and the layer name, separated by "\". The problem: "\" is an escape character in Python. I cannot separate the layer name from the group name. I need the layer name, though, because I want to search the .mdx document for that name in order to get the full path to the layer on disc.

Is there some way to solve this?

I tried:

combined_name.split("\\")
combined_name.split(r"\\")
r"{0}".format(combined_name).split("\\")

where combined_name is the respective name extracted from the input variable. All these attempts were without success.

Edit: I tried the arcpy.GetParameter(0) suggestion with no success. This is the Toolbox I used to test it:

import arcpy as ap
# Toolbox
class Toolbox(object):
    def __init__(self):
        self.label = "Tool"
        self.alias = "Tool"
        # List of tool classes associated with this toolbox
        self.tools = [Tool]
class Tool(object):
    def __init__(self):
        self.label = "Tool"
        self.description = "Test GetParameter(0)."
        self.canRunInBackground = False
    def getParameterInfo(self):
        """Define parameter definitions"""       
        in_raster = ap.Parameter(
            displayName = "Input Raster",
            name = "Raster",
            datatype = ["GPRasterLayer", "DERasterDataset"],
            parameterType = "Required",
            direction = "Input",
            multiValue = True)
        params = [in_raster]
        return params
    def isLicensed(self):
        """Set whether tool is licensed to execute."""
        return True
    def updateParameters(self, params):
        return
    def updateMessages(self, params):
        return
    def execute(self, params, messages):
        rasters = ap.GetParameter(0)
        if rasters is None:
            ap.AddMessage("Parameter is of type None.")
        else:
            ap.AddMessage("Parameter is something other then None.")
        return

When I open the Tool dialogue and add some rasters to the list, I get the "Parameter is oy type None" message after running the tool.

[RichardHowe]

Instead of grabbing the input as text, you could grab the item itself using:

arcpy.GetParameter()

Then use a for loop to access the layer properties

e.g.:

layernames = arcpy.GetParameter(0)

for l in layernames:
   arcpy.AddMessage(l.name)

[Manu]

Unfortunately, arcpy.GetParameter(0) returns "None" for my ArcMap MultiValue input parameter... I guess this only works in ArcGIS Pro.

[RichardHowe]

This should work in ArcMap also. What Data Type do you have your multivalue input as? I've tried it with the option set to Layer and it works

[Manu]

I have some ["GPRasterLayer", "DERasterDataset"] datatype

[RichardHowe]

So it would work with raster layers, but not with a raster dataset, as that can't have a "Layer Name" property anyway. It only has layer properties once it is inside of an MXD or your have cast it as a feature layer, but if that hasn't happened/isn't the case then you wouldn't have the issue with it being part of a group layer anyway, so perhaps you could code around that e.g. an if statement based on feature type then a for loop to access layer name for those inputs that support it.

[Anonymous User]

split() returns a list so you have to use an index to grab the item that you want.  Maybe you are doing this, but its not in your code example?

fc = combined_name.split("\\")[-1]
fc = combined_name.split(r"\")[-1]
fc = r"{0}".format(combined_name.split("\\")[-1])

[Manu]

True, it returns a list. However, it returns a list of a single element which is still the combined name...

[Anonymous User]

maybe try:

fc = str(combined_name).split("\\")[-1]
fc = str(combined_name).split(r"\")[-1]
fc = r"{0}".format(str(combined_name).split("\\")[-1])

[Manu · Accepted solution]

I found some solution (here, I added a condition to check whether the input is some file path that I don't want to mess up. The tool accepts selecting loaded layers from a drop-down as well as browsing files):

def replace_grouped(in_var):
    if not os.path.isfile(in_var):
        out = repr(in_var).strip("'").split("\\")[-1]
    else:
        out = in_var
    return out

or, in practice: Since somehow the ending \'" was introduced to some input variables but not others, I had to do the following

def replace_grouped(in_var):
    if not os.path.isfile(in_var):
        out = repr(in_var).strip("'").strip('"').strip("'").strip('"') \
            .split("\\")[-1]
    else:
        out = in_var
    return out

(very ugly, but I haven't found a better way to get rid of the trailing garbage yet.)