Arcade expression to calculate average

[CPoynter]

I have a table with five fields for sampling records and a sixth field for a mean/average value to be calculated in.

I have used the Arcade command 'Average' within 'Field Calculator', but find it does not calculate a correct value when 0 values are recorded within some fields.

Average($feature.fld0,$feature.fld1,$feature.fld2,$feature.fld3,$feature.fld4)

Average(1,2,3,0,0) should equal (1+2+3) / 3 = 2, but the value I am getting is (1+2+3+0+0) / 5 = 1.2

What would be the expression to calculate the correct average value when some fields have 0 values (ie. exclude fields with a 0 value from the calculation)?

[DanPatterson]

You  can Arcade the logic from this python example

# python... enclose field names in ! eg. !f0!
# example row
f0, f1, f2, f3, f4 = 3, 2, 1, 0, 0

sum([f0, f1, f2, f3, f4])/len([i for i in [f0, f1, f2, f3, f4] if i > 0])
2.0

[JohannesLindner]

function non_zero_average(values) {
    var non_zero = []
    for(var i in values) {
        var v = values[i]
        if(!IsEmpty(v) && v != 0) {
            Push(non_zero, v)
        }
    }
    return Average(non_zero)
}
return non_zero_average([1, 2, 3, 0, null])

[jcarlson]

Just to throw another approach on the heap, we can use Filter to simply drop those zeroes and nulls as well.

var vals = [1, 2, 3, 0, 0, Null]

function DropEm(value){ DefaultValue(value, 0) != 0 }

Average(Filter(vals, DropEm))

It still pales in comparison to the concision of Python, though.

[Ministry_of_Forestry_Fiji]

Having the same problem and am unable to understand any of the replies above being almost novice in programming, although they make sense to me. My function is as follows: 

Average($feature.Qrt1_2022, $feature.Qrt2_2022, $feature.Qrt3_2022, $feature.Qrt4_2022)

All I want it to do is don't account for 0 values.

Thanks in advance.

[JohannesLindner]

Let's look at Josh's answer above you. What it does is the following:

• get an array of values
• define a function with which to filter this array. this function returns true if you want the value to stay in the array. we want a value to stay in the array if it is unequal to zero (!=0). but we also have to account for null values. that's what DefaultValue does: it returns the value if it is not null and returns a default value (0 in this case) if it is null.
• filter the array
• get the average of the filtered array

So, if we apply Josh's answer to your problem (and make the steps more obvious):

// get an array of values
var values = [$feature.Qrt1_2022, $feature.Qrt2_2022, $feature.Qrt3_2022, $feature.Qrt4_2022]

// define a function that we use to filter the array
// returns true (keep value) if value is not null and is unequal to 0
function drop_zero(value) {
    var non_null_value = DefaultValue(value, 0)  // value is null? -> value = 0
    return non_null_value != 0
}

// filter the array
var filtered_values = Filter(values, drop_zero)

// return the average of the filtered array
return Average(filtered_values)

[Mohammed_Abdullah_BinShorab]

Thank you. This was very helpful.