Calculating field values only for appropriate features using ArcMap

[RafaelMichael]

Just like in the attached picture. I would like to calculate the value for the field "indeks_star" with the formula: indeks_star =[TOT_65__] / [TOT_0_14] * 100

And for features where in the field TOT_0_14 occurs 0 or in [TOT_65__] occurs 0, I would like the value -9999 to appear in the field indeks_star.

What formula to enter in the field calculator to simultaneously calculate all values for the field indeks_star?

[DavidPike · Accepted solution]

Hello again,

on field calculator, select Python as your parser (top radio button) and select 'show codeblock' which appears in the middle of the window.

where it has whitespace below 'pre-logic script code' insert the code below

def percentage(field1, field2) :

    if field1 != 0 and field2 != 0 :
        return ( (float(field1) / float(field2) ) * 100.0)

    else :
        return -9999‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

in the bottom bit of whitespace it should have something like 'indeks_star =' above it in the greyed out area.  in the whitespace type out this:

percentage(!TOT_0_14!, !TOT_65!)

[RafaelMichael]

shouldn't it be the other way around?

no 
percentage(!TOT_0_14!, !TOT_65!)         but      percentage( !TOT_65!, !TOT_0_14!)

[DavidPike]

Depends which way round you want it really, in your question you wanted _14/_65 ?

[RafaelMichael]

I just edited the post now. Sorry for the mistake. Should be [TOT_65__] / [TOT_0_14] * 100

so it will be          percentage( !TOT_65__!, !TOT_0_14!)      ?

[DavidPike]

Yeh should work

[RafaelMichael]

many features calculated correctly, many -9999(no problem), but there are also many cases when the value of the field indeks_star should be calculated, but a value of 0 for this field is created.

[DavidPike]

Maybe it's doing integer division. I'll amend the code now

[RafaelMichael]

all values seem fine now. thank you!!! I have to create one more field and calculate one more formula, will you wait 5 minutes? I'm already putting it here

[RafaelMichael]

AProchow = (TOT_65/TOT)*100

if field TOT is 0 or field TOT_65__ is 0   then field  AProchow equals -9999