topic Re: GetParameter() - Double Value needs to be re-cast as a Double (from string) in Python Questions

GetParameter() - Double Value needs to be re-cast as a Double (from string)

MGAL — Thu, 11 Dec 2025 17:37:51 GMT

In my tool, I have one parameter that accepts a double value. In my script, I have to re-cast the value as a float() type.

proximity_threshold = float(arcpy.GetParameterAsText(1))

This feels kind of silly to have to re-cast the value that was originally input as the correct data type.

Is there a more elegant solution here that I'm not seeing?

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

AlfredBaldenweck — Thu, 11 Dec 2025 17:43:00 GMT

Yeah just use arcpy.GetParameter()

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

MGAL — Thu, 11 Dec 2025 18:20:07 GMT

That's what I thought too...

When I change the line to...

proximity_threshold = arcpy.GetParameter(1) arcpy.AddMessage(proximity_threshold) arcpy.AddMessage(type(proximity_threshold))

if near_dist < proximity_threshold:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: '<' not supported between instances of 'float' and 'str'

Messages before the failure show 10, and <class 'str'> respectively. Here's my tool parameter config for good measure.

-M

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

DavidSolari — Thu, 11 Dec 2025 18:42:56 GMT

Alfred's suggestion is the intended way to get a Double parameter so I can't say why it's failing for you. As a workaround, try getting all your parameters using arcpy.GetParameterInfo() and then use the value or valueAsText parameters as needed. For example, a drop-in replacement for the first line of your sample is:

proximity_threshold = arcpy.GetParameterInfo()[1].value

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

AlfredBaldenweck — Thu, 11 Dec 2025 18:56:53 GMT

Dumb question, but what's the parameter type of near_dist?

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

MGAL — Thu, 11 Dec 2025 20:24:51 GMT

near_dist isn't a parameter... it's derived from the script. it's the variable for the output of .distanceTo() the geometry method (outputs double).

the script joins information from two different line feature classes, to a table of inspection points. where the tables' ID's don't match 1:1 (for reasons i don't want to get into :/) the script reverts to a proximity match. the proximity match is the min threshold that automatically matches the line to the point.

def find_closest_line(pcs_geom, input_fc, oid_idx, shape_idx, proximity_threshold): near_dists = {} for feats in input_fc: for k,v in feats.items(): oid = v[oid_idx] shape = v[shape_idx] near_dist = pcs_geom.distanceTo(shape) if near_dist < proximity_threshold: # arcpy.AddMessage("Bullseye!") return list(feats.values())[0] else: near_dists[oid] = near_dist if len(near_dists) == 0: return False closest_oid = sorted(near_dists.items(), key=lambda item: item[1])[0][0] closest_feat = [oid for rows in input_fc for oid in rows.keys() if oid == closest_oid] for feats in input_fc: for k,v in feats.items(): if v[oid_idx] == closest_oid: return v return closest_feat

(note that "input_fc" is really a list of python dictionaries derived from SearchCursor)

depending on the size & location quality of the incoming dataset, this value can be adjusted to speed up the process, or slow down the process to get better accuracy. the tool also has a boolean parameter that puts the process into a test mode to allow the user to see the results as a formatted arcpy message, before the data is appended to the master inspection table.

not a dumb question!

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

DanPatterson — Thu, 11 Dec 2025 20:27:29 GMT

you can float both with issue in python

(float(1) == float("1")) and (float("1.0") == float(1.0)) True

so if it isn't an integer, float/double or text, what is it?

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

MGAL — Thu, 11 Dec 2025 20:38:14 GMT

That worked...

I'm still not understanding why the double data type is so buried in the tool. For example, I also have a boolean parameter in this tool, and the ".GetParameter()" method works w/o transformation.

In my mind, the toolboxes parameters should dictate the data type of the incoming data as it was configured in the toolbox. Otherwise, what's the point of setting a data type?

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

DanPatterson — Thu, 11 Dec 2025 20:44:46 GMT

It is one reason that I use the old school sys.argv

Accessing parameters in a script tool—ArcGIS Pro | Documentation

you just have to remember that sys.argv[0] is the script and sys.argv[1] is parameter id 0

Re: GetParameter() - Double Value needs to be re-cast as a Double (from string)

AlfredBaldenweck — Fri, 12 Dec 2025 15:58:16 GMT

So, I tested this just now on 3.5.5 and I don't have any problem?

""" Script documentation - Tool parameters are accessed using arcpy.GetParameter() or arcpy.GetParameterAsText() - Update derived parameter values using arcpy.SetParameter() or arcpy.SetParameterAsText() """ import arcpy def script_tool(param0): """Script code goes below""" x = float(10) y = param0+x arcpy.AddMessage(y) return if __name__ == "__main__": param0 = arcpy.GetParameter(0) script_tool(param0)

I'd double-check the types of everything again. You can arcpy.AddMessage(type(x)) to make sure.

If everything is actually as intended, this is super weird and would probably worth trying to replicate in an unrelated toolbox with a very simple tool (as above).