Custom Expression to Assign Colors in Symbology
Your expression for "Overlay - 8" is wrong!
You labeling expression can be massively simplified:
var pt = [
$feature.Points_1,
$feature.Points_2,
$feature.Points_3,
]
// count the zeroes
var zeroes = 0
for(var p in pt) { zeroes += pt[p] == 0 }
// all values are zero -> None
if(zeroes == 3) { return "None" }
// two values are zero -> return the non-zero value
if(zeroes == 2) {
if(pt[0] > 0) { return "Overlay - " + pt[0] }
if(pt[1] > 0) { return "Seal - " + pt[1] }
if(pt[2] > 0) { return "Crack Fill - " + pt[2] }
}
// one or no value(s) are zero -> return all non-zero Trtmt values and the sum of the Points values
var trtmt = [
$feature.Trtmt_1,
$feature.Trtmt_2,
$feature.Trtmt_3,
]
var trt = []
for(var t in trtmt) {
if(pt[t] > 0) { Push(trt, trtmt[t]) }
}
return Concatenate(trt, ", ") + " - " + Sum(pt)
You can input that expression into the symbology as Unique Value "field":
This will give you a legend like this:
But that's not really practical. There are 65 conditions in your original expression, and there are actually a lot more possible values, because you take the sum of all non-zero Point values. You would have to format all the colors, and it wouldn't provide any useful information to your viewers, because the color would be too similar.
In my opinion, a better way would be to only symbolize the combination of treatments and only display the actual values in the label.
This is the last part of the label expression, slightly adapted:
var pt = [
$feature.Points_1,
$feature.Points_2,
$feature.Points_3,
]
var trtmt = [
$feature.Trtmt_1,
$feature.Trtmt_2,
$feature.Trtmt_3,
]
var trt = []
for(var t in trtmt) {
if(pt[t] > 0) { Push(trt, trtmt[t]) }
}
if(Count(trt) == 0) { return "None" }
return Concatenate(trt, ", ")
And this gives you a much more manageable legend (only 8 items) that actually provides information to your viewers:
Together with the labels:
OK, I may have found a solution that works.
You can enable symbol property connections in the symbology, which lets you choose your color programmatically (or with a field). I didn't suggest that originally, because this isn't reflected in the legend.
But luckily, you have three treatment types which you can let correspond to the three color channels of an RGB value (red, green, blue). You can then vary the lightness of the color by using the rgb channel of the missing treatment(s). The varying lightness won't show up in the legend, so you have a manageable number of items there, and your viewers can get a sense of your point system. But they won't be able to directly get the points by looking at the color, because the color doesn't show up in the legend, so they still have to rely on labels or popups for that.
- Overlay corresponds to the red channel, Seal corresponds to the green channel, Crack Fill corresponds to the blue channel.
- Use the symbology expression from my previous answer and set the colors accordingly (you have to do that manually). This is just for the legend, the actual symbol color won't be affected by this. I chose gray instead of white for all 3 treatments:
- Allow symbol property connections
- For each of the treatment combinations (except None), map the symbol color to the expression below.
- The first three lines of the expression control how the color will be varied.
- rgb_channel_min: the minimum value for the missing channels (RGB channels go from 0 to 255). This should be 0 except for all 3 treatments, 100 works nicely there.
- rgb_channel_max: the maximum value for the missing channels. Don't set it too high, else your points are just white. Values I found to work:
- 1 treatment: 200
- 2 treatments: 230
- 3 treatments: 250
- low_values_are_lighter: Should low point values be lighter than high point values?
var rgb_channel_min = 0
var rgb_channel_max = 200
var low_values_are_lighter = false
var pt = [
$feature.Points_1,
$feature.Points_2,
$feature.Points_3,
]
var zeroes = 0
for(var p in pt) { zeroes += Includes([null, 0], pt[p]) }
var value = Sum(pt)
var max_value = (3 - zeroes) * 10.5
var normalized_value = value / max_value
var rgb_channel = IIf(low_values_are_lighter,
rgb_channel_max - normalized_value * (rgb_channel_max - rgb_channel_min),
rgb_channel_min + normalized_value * (rgb_channel_max - rgb_channel_min)
)
var rgb = [0, 0, 0]
for(var p in pt) {
rgb[p] = IIf(pt[p] > 0 && zeroes > 0, 255, Round(rgb_channel))
}
return `rgb (${Concatenate(rgb, ", ")})`
So it's still a little manual work, but only for 8 items, not for 65+. Here is the result:
