# Multiple Conditional Reclassification - ArcGIS

This is a question out of curiosity rather than a problem as I am not the most experienced with raster datasets and I wonder if there is a better solution to my current approach. I am trying create a new raster dataset based off the conditions of two raster datasets. i.e. if population size <100 and mean age <10, reclassify to value 1. Now the issue is not creating a conditional statement but if there are several possible categories - say 49, that would require 49 multiple conditional statements. For example:

``````OutRas = Con((pop_ras < 100) & (age_ras < 10), 1, Con(pop_ras > 100) & ((pop_ras < 200) & (age_ras  < 10), 2, ..., 0))
``````

At the moment I use the following procedure:

1) reclassify population into 7 categories

2) reclassify age into 7 categories

3) add age and population (to create 49 classes)

This approach would require 3 geoprocessing steps as opposed to one but require considerable less time scripting. I feel that there might be a simpler solution that I am not realization (perhaps a lookup table, SQL). Any thoughts? ideas? Which method is better - speed?

• I don't follow: 49 conditional statements is (at least) 49 geoprocessing steps, not one. How do you solve this problem with fewer than three grid operations? Dec 2, 2011 at 2:18
• This would be a good question for the r-geo-sig. Dec 2, 2011 at 3:12
• Dec 2, 2011 at 3:29
• @whuber What I meant is the use of 49 conditional statements within one function line. See under multiple conditional statements at help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//… Dec 2, 2011 at 8:50
• The example you have included helps me understand what you mean, thanks. I just want to point out how inefficient this is: each of the terms, such as "pop_ras < 100", requires an entire grid operation, and each of the conjunctions, such as "&", requires another, and so does each "Con". That potentially has you doing hundreds of grid operations in order to achieve something that can be done in three operations: two reclassifications and a 'combine' (your step 3). Moreover, what's simple for ArcGIS is also simple and clear to code, which is more reliable and maintainable. Dec 2, 2011 at 14:50