topic Re: Converting String-Values into doubles in ModelBuilder Questions

Converting String-Values into doubles

KevinBullenkamp1 — Thu, 10 Aug 2017 13:19:46 GMT

Hello everyone, I got a string variable as an input parameter, where you can choose between yes or no. Now I would like to use this input in the "Raster calculator", so the string should be converted in a double (values 1 and 2). My programming skills are not that powerful so Python was not option for me. So I tried it via "Calculate Value" in the Model Builder but my block Code did not work at all (perhaps because of my programming skills...). Hopefully you got a solution for my problem. Sorry for my bad english btw...

Greetings from Germany

Kevin

Re: Converting String-Values into doubles

curtvprice — Sun, 12 Dec 2021 05:46:54 GMT

Here's a Calculate Value expression that will do what you want. Rename the Calculate Value output "OptValue"

# expression
f(r"%Option%")

# code block
def f(opt):
    if opt == "YES": 
        return 1.0
    else: 
        return 2.0
# data type: Double‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Then, open the Raster Calculator tool and build this expression.

This is the python float function (lower case, not the arcpy.sa tool Float)

"%raster dataset%" * float(%OptValue%)‍‍‍‍‍‍‍‍

Re: Converting String-Values into doubles

curtvprice — Thu, 10 Aug 2017 19:43:55 GMT

UPDATE: the float() is not necessary - it works without it.

Executing (Calculate Value): CalculateValue f("YES") "def f(opt):\n if opt == "YES":\n return 1.0\n else:\n return 2.0" Double
Start Time: Thu Aug 10 13:39:45 2017
Value = 1
Succeeded at Thu Aug 10 13:39:45 2017 (Elapsed Time: 0.06 seconds)
Executing (Raster Calculator): RasterCalculator ""dem_anal_Clip" * 1" D:\Users\cprice\work\inc\zstats_issue\zonalstats_issue.gdb\rastercalc
Start Time: Thu Aug 10 13:39:45 2017
Raster(r"dem_anal_Clip") * 1
Succeeded at Thu Aug 10 13:39:46 2017 (Elapsed Time: 0.68 seconds)

Re: Converting String-Values into doubles

KevinBullenkamp1 — Thu, 10 Aug 2017 20:33:45 GMT

Thanks alot! It is working!

Re: Converting String-Values into doubles

curtvprice — Thu, 10 Aug 2017 21:13:17 GMT

You are welcome! Please do mark my answer correct so others can easily find it.

For the good of the thread, here's a fancier one-line Calculate Value expression (no code block needed) to convert a string to a float value. I am using a Python dictonary data structure to do this.

{"YES":1.0, "NO":2.0}["%Option%"]‍‍‍‍

UPDATE:

and -- if only a binary choice, we can use Python's ternary if construct

1.0 if "%Option%" == "YES" else 2.0‍‍‍