topic Re: How to obtain number of cells in neighborhood from NbrWeight neighborhood object? in Python Questions

How to obtain number of cells in neighborhood from NbrWeight neighborhood object?

AmelieDavis — Thu, 15 Oct 2015 17:06:59 GMT

Hi,

I'd like to get the first two numbers in the .txt file that is loaded as by NbrWeight (neighborhood object weights) for the focal statistics tool.

I want to use them to calculate the area of the rectangle that is the neighborhood.

How do I easily access the values?

Here is what I have so far:

inWeightFile = arcpy.GetParameterAsText(5)

if inWeightFile == '#' or not inWeightFile:

inWeightFile = "C:\\temp\\PPR\\Test\\bee_kernel_2_5km.txt" # provide a default value if unspecified

# Create the Neighborhood Object for the buffer

myNbrWeight = arcpy.sa.NbrWeight(inWeightFile)

# Get number of cells in the buffer

NbrCellsBuffer = 65 * 65 # XXX need to fix this. Should come from first two numbers in inWeightFile

# Process: Focal Statistics - within buffer calculate sum of f_rc1_H1 with exponential decay function and divide by number of cells in buffer

arcpy.AddMessage("Calculate proportional cover of high floral quality classes within buffer for first floral season")

f_rc_f_H1 = (arcpy.sa.FocalStatistics(f_rc1_H1, myNbrWeight, "SUM", "NODATA") * outConstRaster) / NbrCellsBuffer

Any help is greatly appreciated.

Best,

Amelie

Re: How to obtain number of cells in neighborhood from NbrWeight neighborhood object?

DanPatterson_Retired — Thu, 15 Oct 2015 20:06:16 GMT

showing the text file would be useful

Re: How to obtain number of cells in neighborhood from NbrWeight neighborhood object?

AmelieDavis — Thu, 15 Oct 2015 21:18:15 GMT

yes, sorry.

The text file is just the kernel they talked about here ArcGIS Desktop saved as a .txt.

I'm attaching my kernel (it's a bit more complicated than the examples provided in the help).

Amelie

Re: How to obtain number of cells in neighborhood from NbrWeight neighborhood object?

Luke_Pinner — Sat, 11 Dec 2021 20:38:03 GMT

ncols, nrows = [int(s) for s in open(inWeightFile).readlines()[0].strip().split()]
NbrCellsBuffer = ncols * nrows

The above opens the file and grabs the first line, strips off the newline ('\n') character and splits it into a list of two strings at the space then uses python list comprehension to convert the strings to integer values.

Re: How to obtain number of cells in neighborhood from NbrWeight neighborhood object?

curtvprice — Fri, 16 Oct 2015 01:43:26 GMT

Amelie,

Irregular neighborhoods could be implemented better in arcpy. Here's more fun I've had with them:

Working with kernel files in arcpy: NbrIrregular bug

That is one massive kernel file!