Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Hi I am a beginner to python programming in GIS and am trying to calculate the area of a raster. When I ran the program, I got error message below. I am also providing my code. Any help would be greatly appreciated!

import arcpy
from arcpy import env

#To overwrite output
arcpy.env.overwriteOutput = True

#Set environment settings
env.workspace = "C:/Subhasis/Test/raster-read"

#set local variables-STI extraction
inRaster ="sti"

# Create a search cursor for raster attribute
read = arcpy.SearchCursor("inRaster","","","Value;Count","")

#read the counts in raster
for row in read:
    count = row.getValue("Count")

    print count

Error Message:

"Traceback (most recent call last):
  File "C:/Subhasis/Test/raster-read/", line 14, in <module>
    read = arcpy.SearchCursor("inRaster","","","Value;Count","")
  File "C:\Program Files (x86)\ArcGIS\Desktop10.2\arcpy\arcpy\", line 1167, in SearchCursor
    return gp.searchCursor(dataset, where_clause, spatial_reference, fields, sort_fields)
  File "C:\Program Files (x86)\ArcGIS\Desktop10.2\arcpy\arcpy\geoprocessing\", line 359, in searchCursor
    self._gp.SearchCursor(*gp_fixargs(args, True)))
IOError: "inRaster" does not exist"
share|improve this question
You variable is inRaster but you are passing it to your search cursor as a string "inRaster". Also, you should look into the data access module for an updated cursor object that's faster and more reliable. – Paul Jul 11 '14 at 14:23
Try throwing a print statement after you define inRaster...if it fails, perhaps you need a / after raster-read – Dan Patterson Jul 11 '14 at 14:24
like @Paul said remove the quotes from inRaster in your search cursor also use arcpy.da.SearchCursor() instead. – Chris R Jul 11 '14 at 15:01

A very simple way to calculate the area of a raster is:

raster = <path to raster>
ext = arcpy.Describe(raster).extent
area = ext.width * ext.height
share|improve this answer
This method includes the area of cells with NoData values. – Luke Jul 11 '14 at 22:10

The following script uses a SearchCursor to extract the "Count" field rows. You can see that I am using the da module, which is available with ArcGIS 10.1+ as this method is much more efficient.

import arcpy

raster = r'C:\path\to\raster'

# Create a search cursor for raster attribute
with arcpy.da.SearchCursor(raster, ["OBJECTID", "COUNT"]) as cursor:
    for row in cursor:
        # You may need to do a conversion if pixels are in units other than m
        print "OID %s has an area of %s m^2" % (row[0], row[1])

enter image description here enter image description here

share|improve this answer
Thank you very much Paul, dan, Chris,and Aaron for your time and help!. I removed the quotes from inRaster and used arcpy.da.SearchCursor() instead of arcpy.SearchCursor(). I did get an error below: Error: Traceback (most recent call last): File "C:/Subhasis/Test/raster-read/", line 15, in <module> read = arcpy.da.SearchCursor(inRaster,"","","Value;Count","") RuntimeError: cannot open 'sti' – Inception Jul 11 '14 at 17:40
Thank you Roman! I used your code and got some number. But little bit confused regarding the units as it doesn't provide the units. Anyways, again thanks a lot guys for your help! This is pretty helpful for beginner like me in scripting in GIS. I was wondering "Could you please suggest me (beginner to Python scripting) some books or any website that would help me learning Python script for GIS. Have a good weekend guys! – Inception Jul 11 '14 at 18:18
@Subhasis Regarding the units, lets say you have a pixel count of 10 and your pixels are at 1m spatial resolution. This means that the total area is 10 m^2. You can convert this to whatever you want (e.g. acres, hectares, ft etc). – Aaron Jul 11 '14 at 18:36
Thank you Aaron! – Inception Jul 11 '14 at 18:38

Instead of using cursors to find the raster area I would use Describe and use the raster band properties to find the area of my raster. Once I know the cell width, cell height, raster width, and raster height of my raster I can calcuate its area. However, this method does not give the units of the raster, you'll need to know them ahead of its calculation.

For example:

arcpy.env.workspace = r"C:\Example_Workspace"
rast = "ExampleRaster"
descRast = arcpy.Describe(rast)
x_cell = descRast.meanCellWidth
y_cell = descRast.meanCellHeight
x_rast = descRast.width
y_rast = descRast.height

rasterHeight = y_cell * y_rast
rasterWidth = x_cell * x_rast
rasterArea = rasterHeight * rasterWidth

print "The area of {0} is {1}".format(rast, rasterArea)
share|improve this answer
I think you mean descRast = arcpy.Raster(rast)? Describe objects don't have all of those properties. – Paul Jul 11 '14 at 16:41
Nope, Raster Band Properties are included in arcpy.Describe(). Describe(arcpy), Geoprocessor Program Model – Roman Jul 11 '14 at 17:00
Ahh, but if you look closely, it says that it only works on " Raster Bands". If you try that with a 3 band image, it fails. Add only one of the bands, and it works. – Paul Jul 11 '14 at 17:10

There's another "Ah..." here as well. If you make a raster object from the raster reference like :

PathtoMyRaster = "c:/Temp/MyRaster.tif"
ras = arcpy.Raster(PathtoMyRaster)

Then the raster object has properties like : . bandCount, extent, mean, min, max, meanCellHeight, meanCellWidth, height, width. So you can access them that way

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.