[GIS] Script for Sum of Rows in field calculator – VB or Python

arcgis-desktoparcpyfield-calculatorpython-parser

I wrote the TOTAL_FREQUENCY values manually. But I want to automatically write this values with a script. Namely, I want to write sum of column 3 to all of the the column 5 rows. How can I do it with a script?

Best Answer

The following standalone-script should do the work for ArcGIS 10.x:

import arcpy

arcpy.env.workspace = 'myGeodatabase'

cursor = arcpy.SearchCursor('myLayer', ['frequency'])
sum = 0
for row in cursor:
    sum += row[0]

cursor = arcpy.UpdateCursor('myLayer', ['total_frequency'])
for row in cursor:
    row[0] = sum
    cursor.updateRow(row)

del cursor

Related Solutions

ArcGIS – Field Calculator Python Numbering Rows of Fishnet

Calculate based on the shape Xmin minus the feature class Xmin (the origin), the divide by the cell width.

So The function will be something like:

get_rownum(!shape.extent.XMin!, !shape.extent.XMax!)

And the code block will be something like:

def get_rownum(xmin, xmax):
    return (xmin - origin) // (xmax - xmin) #fill in the origin

For help see some examples of using field calculator.

ArcPy – How to SUM Field and Insert into NULL Column Using ArcGIS 10.2

Cursors are the way to go for this type of problem.

First, create a list of values using a Search Cursor and a generator expression:

b = sum(row[0] for row in arcpy.da.SearchCursor(fc, 'QUANTITY_SOLID'))

Then run an Update Cursor to populate the QUANTITY_SOLID_SUM field:

with arcpy.da.UpdateCursor(fc, ['QUANTITY_SOLID_SUM']) as cursor:
    for row in cursor:

Finally, update the rows with the value from the generator

    row[0] = b
    cursor.updateRow(row)

import arcpy

# Define the feature class
fc = r'C:\path\to\your\fc'

# Use a generator expression to populate a list from the 'QUANTITY_SOLID' field
b = sum(row[0] for row in arcpy.da.SearchCursor(fc, 'QUANTITY_SOLID'))

with arcpy.da.UpdateCursor(fc, ['QUANTITY_SOLID_SUM']) as cursor:
    for row in cursor:
        row[0] = b
        cursor.updateRow(row)

Best Answer

Related Solutions

ArcGIS – Field Calculator Python Numbering Rows of Fishnet

ArcPy – How to SUM Field and Insert into NULL Column Using ArcGIS 10.2

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