Hi @jhwang ,

You can use Math operation to do this.

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Hi @Shashi,

I tried to calculate the distance between two coordinates, but I failed.

Here is my code:

Qualtrics.SurveyEngine.addOnReady(function()
{

var R = 6371;
var t1_dx = parseFloat("${e://Field/t1_dx}");
var t1_ox = parseFloat("${e://Field/t1_ox}");
var t1_dy = parseFloat("${e://Field/t1_dy}");
var t1_oy = parseFloat("${e://Field/t1_oy}");


var latDistance = Math.toRadians(t1_dx - t1_ox);
var lonDistance = Math.toRadians(t1_dy - t1_oy);
var a = Math.sin(latDistance / 2) * Math.sin(latDistance / 2)
+ Math.cos(Math.toRadians(t1_ox)) * Math.cos(Math.toRadians(t1_dx))
* Math.sin(lonDistance / 2) * Math.sin(lonDistance / 2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
var distance = (R * c * 1000) / 1609.344; // convert to miles

var height = 0.00;

var distance2 = Math.pow(distance, 2) + Math.pow(height, 2);

var dist1 = Math.sqrt(distance2);

Qualtrics.SurveyEngine.setEmbeddedData("dist1", dist1);
});


Could you or anyone please correct my code?

Thank you very much.

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Hi @jhwang

Please use the below code:

function getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) {
var R = 6371; // Radius of the earth in km
var dLat = deg2rad(lat2-lat1); // deg2rad below
var dLon = deg2rad(lon2-lon1);
var a =
Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
Math.sin(dLon/2) * Math.sin(dLon/2)
;
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c; // Distance in km
return d;
}

function deg2rad(deg) {
return deg * (Math.PI/180)
}

---

@Shashi,

Thank you for your suggestion. But I still cannot see the embedded data value of the distance.

Here is my code:

Qualtrics.SurveyEngine.addOnReady(function()
{
var R = 6371;
var lat2 = Number("${e://Field/t1_dx}");
var lat1 = Number("${e://Field/t1_ox}");
var lon2 = Number("${e://Field/t1_dy}");
var lon1 = Number("${e://Field/t1_oy}");

function getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) {
var R = 6371; // Radius of the earth in km
var dLat = deg2rad(lat2-lat1); // deg2rad below
var dLon = deg2rad(lon2-lon1);
var a =
Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
Math.sin(dLon/2) * Math.sin(dLon/2)
;
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c; // Distance in km
return d;
}

function deg2rad(deg) {
return deg * (Math.PI/180)
}

Qualtrics.SurveyEngine.setEmbeddedData("dist1", d);

});

Here is more detailed information of variables:
* Coordinates of origin: (`t1_ox`, `t1_oy`)
* Coordinates of destination: (`t1_dx`, `t1_dy`)

I checked if the embedded data of `t1_ox` ~ `t1_dy` work, and confirmed that they have no issues.

However, I cannot see the embedded data of `dist1`.

Thank you.

---

> @jhwang said:
> @Shashi,
>
> Thank you for your suggestion. But I still cannot see the embedded data value of the distance.
>
> Here is my code:
>
> Qualtrics.SurveyEngine.addOnReady(function()
> {
> var R = 6371;
> var lat2 = Number("${e://Field/t1_dx}");
> var lat1 = Number("${e://Field/t1_ox}");
> var lon2 = Number("${e://Field/t1_dy}");
> var lon1 = Number("${e://Field/t1_oy}");
>
> function getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) {
> var R = 6371; // Radius of the earth in km
> var dLat = deg2rad(lat2-lat1); // deg2rad below
> var dLon = deg2rad(lon2-lon1);
> var a =
> Math.sin(dLat/2) * Math.sin(dLat/2) +
> Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
> Math.sin(dLon/2) * Math.sin(dLon/2)
> ;
> var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
> var d = R * c; // Distance in km
> return d;
> }
>
> function deg2rad(deg) {
> return deg * (Math.PI/180)
> }
>
> Qualtrics.SurveyEngine.setEmbeddedData("dist1", getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) );
>
> });
>
> Here is more detailed information of variables:
> * Coordinates of origin: (`t1_ox`, `t1_oy`)
> * Coordinates of destination: (`t1_dx`, `t1_dy`)
>
> I checked if the embedded data of `t1_ox` ~ `t1_dy` work, and confirmed that they have no issues.
>
> However, I cannot see the embedded data of `dist1`.
>
> Thank you.

Change the last line to:

`Qualtrics.SurveyEngine.setEmbeddedData("dist1", getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) ); `

Hope you have created an embedded data dist1 in the survey flow before this question

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