Get route m-value at point-clicked using Arcade?

[NickHarvey]

Hi All - I see that it is possible to access x,y,z, & m values for a custom pop-up using Arcade. The code below appears to be working in ArcGIS Pro 2.5.0 per my route layer:

var line = Geometry($feature)
var paths = line.paths;
var startingpoint = paths[0][0];
return text(startingpoint)‍‍‍‍‍‍‍‍‍‍‍‍

However, I'm not yet understanding how to return the m-value for any point along the route that was clicked, rather than the centroid or endpoints.  The m-value I'm looking for appears in the pop-up panel at lower right in ArcGIS Pro 2.5.0 (see pic below). 

Any assistance appreciated!  

[BenTurrell]

Hey Nick Harvey‌,

Try this:

var line = Geometry($feature)
var paths = line.paths;
var startingpoint = paths[0][0]["x"];
return text(startingpoint)

Thanks,

Ben

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[NickHarvey]

Thanks for chiming in Ben - You're right...I can get to the m-value for the starting point of the route by replacing "x" with "m" for example...But I'm chasing the m-value for any point along the route, as it appears at the bottom of the pop-up panel at 2.5.0 where the route is clicked.  My idea was to build a calculation(expression) in the pop-up which uses this m-value as a variable.  The m-value is being populated at the bottom of the pop-up panel.  I'm not understanding how to reference it into the pop-up body though (?). 

[Anonymous User]

Hi Nick,
Did you make any progress with this?
I'm writing the same expression for start, end and current m values.

var line = Geometry($feature)
var paths = line.paths;
var firstpoint = paths[0][0]["m"];
var lastpoint = paths[0][Count(paths[0])-1]["m"];
var currentpoint = paths

["m"]
return text(currentpoint)

But have no idea what to put in place of the * shown above.
Is this even the correct approach to using M-values in pop-ups?

[NickHarvey]

Hey thanks for responding Nicholas - No progress sorry to say...Yeah, my guess is that it is not the right approach for retrieving m-values dynamically along the line because our Arcade expressions above each refer to a specific vertex (?).  As my picture above depicts - m-values do show up in the standard popup though (at bottom right)...I wonder about SDK (?)         

[XanderBakker · Accepted solution]

Hi Nicholas Flett and nickharvey 

The limitation with Arcade is that you start off with the geometry you clicked on (you M-enabled line) and not the point location of where you clicked. Therefore, it is not possible to determine at which location of the line feature you clicked when using Arcade. The SDK should allow you to do this, although the complexity of the implementation will increase. 

[JosephJordan]

This is FINALLY possible, with the addition of the $userInput profile variable!  Try this:

var geom=Geometry($feature)
var densegeom=Densify(geom, 1)
var PTC=PointToCoordinate(densegeom, $userInput)
var SegNum=PTC.segmentID
var paths=densegeom.paths
var POI = paths[0][SegNum];
return round(POI.m,4)

https://www.youtube.com/watch?v=dddZTpsOjY0

[KatyLewis]

This is gold!!! Thank you so much. Now users can click along a line and get the nearest m value.

[JosephJordan]

Right??! You bet!  I think ESRI has made experience widgets that work if you have Roads & Highways too....but this is nice because you don't have to click a special widget....can just make the Road ID and M value show in the regular pop up.

[DISIG]

Hello Nick,

Hello everybody. I am trying to do the same dynamically in Argis Online.(my point geometry change, my m value change in the map context windows)

I want to use the cut function to get the left length of an intersecting (or nearest) line with M value in a field.

I will write more after testing all that.

i have got to 90° rotate the result of a clip between the buffer of my point and the line.

not easy...

it quite works...

/*
récupérer le cumul par intersection du point avec l'arc.
*/
var CurDep = $feature.ROUTE
var CurBuffGeom =Extent(Buffer($feature, 2, 'meters'))
var CurArcGeom = Back(Filter(FeatureSetById($map, /* tests_arcade - Test li */ "17f27378b8d-layer-3"),'route=@CurDep'))
var CUTTER = rotate(Clip(CurArcGeom,CurBuffGeom),90)
return LengthGeodetic(first(Cut(CurArcGeom, CUTTER)))

note : replaced first with back (when i flip the cutter, 90° the left part is the end part of the line.)