topic Re: How can get the actual Cell Size form "Analysis Cell Size" parameter in Python Questions

How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Sun, 12 Dec 2021 04:47:43 GMT

I am trying to build a Python Toolbox. I need to get the cell size using the following code snippet. Using this parameter you can directly enter the cell size as a number or pick a GIS layer to let the ArcPy to calculate the cell size (If the layer is raster, it will be same as the raster's cell size, otherwise it will be the minimum extent /250).

It is working well and I can use the defined parameter (cell_Size) as Cellsize in any tool (i.e. "Point to Raster"). In my program I need the cell size value (as number) however when you use "cell_Size.valueAsText", you get just the root of the layer as string!

I need the property that I can get the calculated cell size by ArcPy. I tried "cell_Size.Cellsize" , "cell_Size.size" etc. but they are not working.

    # First parameter  
    cell_Size = arcpy.Parameter(  
    displayName = "Cell Size",  
    name = "cell_Size",  
    datatype = "Analysis Cell Size",  
    parameterType="Required",  
    direction="Input ")

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

DanPatterson_Retired — Thu, 11 May 2017 15:41:23 GMT

example = '5'

float(example) => 5 # now a number

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Thu, 11 May 2017 16:57:10 GMT

The parameter type is "Analysis Cell Size".For example:

A = cell_Size.valueAsText

A is "C:\Temp\fgdb.gdb\ASAS"

Although, A apparently is a string, you can use A as cellsize in different tools! but can not get the numeric cell size.

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

DanPatterson_Retired — Thu, 11 May 2017 17:27:36 GMT

ok... it is a filename, which you make into a raster, then get its cell size... I think this is similar to previous issues you were having with what is returned by parameters.

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Thu, 11 May 2017 18:39:11 GMT

Thank you Dan,

In my program, I need the cell size numeric value for a bunch of calculations, before generating the raster. I was thinking about making a virtual raster just to get the size. It is possible but it is weird.

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

XanderBakker — Sun, 12 Dec 2021 04:47:45 GMT

As Dan mentions, when you have a name of a raster as cell size, it means that that raster exists. It references an existing raster and the cell size should be obtained from that raster. You can convert in into a raster object (as Dan mentioned) and access the meanCellHeight and meanCellWidth properties:

import arcpy

def main():
    print GetCellSize('5')
    print GetCellSize('1.234')
    print GetCellSize(r'C:\GeoNet\ModRutaEscombro\gdb\ModRutaEscombros.gdb\CostDist')


def GetCellSize(user_cell_size):
    try:
        # parse to double
        cell_size = float(user_cell_size)
    except:
        # not a numeric value, maybe a reference to an existing raster
        try:
            raster = arcpy.Raster(user_cell_size)
            cell_size = (raster.meanCellHeight + raster.meanCellWidth) / 2.0
        except:
            cell_size = None

    return cell_size

if __name__ == '__main__':
    main()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

This will yield in my case:

5.0
1.234
47.0‍‍‍

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Thu, 11 May 2017 19:23:09 GMT

As I said, when you are using "Analysis Cell Size" as an input data for python toolbox, you can enter number or pick a raster and "Feature class".

in the case of "Feature class", the cell size would be layer extent / 250 (Ersi's default)

Your solution is working for raster and number, however the problem still exists for "Feature class"

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

DanPatterson_Retired — Thu, 11 May 2017 19:37:44 GMT

There is no cell size for feature classes.

If you want to convert a featureclass to a raster, then you have to specify one manually or select an existing raster.

It is as designed.

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Thu, 11 May 2017 19:58:55 GMT

Agree, but when you use the ArcGIS toolbox for example Convert point to raster. For cell size you can just pick Raster. however, when you use "Analysis Cell Size" in your tool which exactly has the same interface of cell size in Convert point to raster tool, you can pick both raster and feature!

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

DanPatterson_Retired — Thu, 11 May 2017 20:48:22 GMT

Not in my ArcMap 10.5 or ArcGIS PRO 1.4.1... point to raster will not even show me featureclasses or shapefiles as a selection option... only rasters, or specify one manually

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

XanderBakker — Sun, 12 Dec 2021 04:47:48 GMT

Actually, I have seen this type of behavior. It is possible to select a featureclass to determine the cellsize. Not in the geoprocessing environment, but in other parts.

Maybe you could try something like:

def GetCellSize(user_cell_size):
    try:
        # parse to double
        cell_size = float(user_cell_size)
    except:
        # not a numeric value
        desc = arcpy.Describe(user_cell_size)
        if hasattr(desc, "datasetType"):
            if desc.datasetType == 'FeatureClass':
                extent = desc.extent
                max_size = max(extent.width, extent.height)
                cell_size = max_size / 250.0
            elif desc.datasetType == 'RasterDataset':
                raster = arcpy.Raster(user_cell_size)
                cell_size = (raster.meanCellHeight + raster.meanCellWidth) / 2.0
            else:
                cell_size = None

    return cell_size‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Fri, 12 May 2017 14:38:23 GMT

Yes, however, when you are developing a python toolbox and using "Analysis Cell Size" parameter to get the cell size, it shows you every thing!

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Sun, 12 Dec 2021 04:47:51 GMT

Thank you,

Do you know how can filter just Raster layers during the parameter definition as follows:

cell_Size = arcpy.Parameter(
    displayName="Cell Size",
    name="cell_Size",
    datatype="Analysis Cell Size",
    parameterType="Required",
    direction="Input")‍‍‍‍‍‍

I tried

cell_Size.filter.list = ["Raster"]‍

But it does not work

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

XanderBakker — Fri, 12 May 2017 14:55:31 GMT

Have look at the datatypes listed here: Defining parameter data types in a Python toolbox—Geoprocessing and Python | ArcGIS Desktop

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Fri, 12 May 2017 15:15:55 GMT

Right know, I found out that we can not use the "Raster" as filter. It is really weird!

Take a look at the following table:

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

XanderBakker — Fri, 12 May 2017 16:54:19 GMT

So, it's not possible to use "DERasterDataset", like in the example mentioned here: Defining parameter data types in a Python toolbox—Geoprocessing and Python | ArcGIS Desktop

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

curtvprice — Sun, 12 Dec 2021 04:47:54 GMT

If you set the cell size environment to the result of valueAsText and the parameter is a raster path, the value set will be the raster's meanCellHeight (as string).

>>> from arcpy import env
>>> env.cellSize = "copy_ras"
>>> env.cellSize
u'10'‍‍‍‍‍‍‍‍‍‍‍‍

If the user does not select a dataset but instead leaves it at Maximum of Inputs, etc. will be a number or a string "MAXOF", "MINOF", etc.

arcpy.env.cellSize = cell_Size.valueAsText
try:
    cell_Size = float(env.cellSize)
except:
    arcpy.AddError("Cell size not numeric: {}".format(cell_Size))‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

You could do this test in the parameter validation if you wanted to trap it before the tool runs.

Another approach I have used is to define my cell size parameter as Double and used parameter validation to have it default to the environment cell size (if set).

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

MohammadrezaNikfal1 — Sat, 13 May 2017 22:39:15 GMT

Yes, After few days struggling, finally, I used Double as cell size.

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

curtvprice — Sat, 03 Jun 2017 18:33:38 GMT

mrnikfal If this was your solution, please mark my answer as correct so others can find it, thanks.

Re: How can get the actual Cell Size form "Analysis Cell Size" parameter

DanPatterson_Retired — Sat, 03 Jun 2017 22:00:03 GMT

double/float.... as a parameter, see the first post