1

I am relatively new to Arc and having a bit of trouble with Extraction. I am using ArcMap 10.4.1 and I have two raster files: one has population data (density per 1km cell) and the other contains a specific disease risk (scale 0-1). Both rasters are the same size (size of cells, number of columns and rows). I want to be able to extract the values from the population raster based on certain values from the disease risk raster; ie how many people reside in areas of 0.6 to 0.7 risk of disease?

I have had a look at the different Extraction options but none offer this option (I think). Do I need to first extract disease risk by attribute using a SQL expression (e.g 0.6-0.7)->transform to polygon->extract population values by 0.6-0.7 risk polygon? Seem like a lot of steps so wondering if there is a more direct way?

2

Use the reclassify tool to create a new raster layer from your risk layer such that values between 0.6 and 0.7 get values of 1 and values outside that range get values of NoData. Then multiply the reclassified data with the population data. This operation will mask out any populations outside of the desired risk zone. The resulting product will be a new raster layer. Assuming your population data is integer data you could open the attributes of that layer and sum the values for a total population count for people in the risk zone. Another approach would be to create a polygon with the same extent as your raster layer and use summary statistics as a table to sum the pixel values.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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