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Feat: Line2D.DistanceTo(Point2D p) #238

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0010a47
Feat: Line2D.DistanceTo(Point2D p)
f-frhs Dec 25, 2023
ffba335
Test: add testcases where the line pass through the point
f-frhs Dec 26, 2023
00ce8a6
Test: Add tests where sp1 and sp2 are swapped
f-frhs Dec 26, 2023
1c444c7
Revert "Test: Add tests where sp1 and sp2 are swapped"
f-frhs Jan 7, 2024
cd80cf1
Test: Add tests where sp1 and sp2 are swapped
f-frhs Jan 7, 2024
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34 changes: 33 additions & 1 deletion src/Spatial.Tests/Euclidean/Line2DTests.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
using System;
using System;
using MathNet.Spatial.Euclidean;
using MathNet.Spatial.Units;
using NUnit.Framework;
Expand Down Expand Up @@ -56,6 +56,38 @@ public void LineDirection(string p1s, string p2s, string exs)
AssertGeometry.AreEqual(ex, line.Direction);
}

public static object[] DistanceTestCases =
{
new object[] { "-1,+1", "+1,+1", "0,0", 1.0 },
new object[] { "-1,+1", "+1,+1", "0,3", 2.0 },
new object[] { "-1,+1", "+1,+1", "0,1", 0.0 },
new object[] { "-1,0", "0,+1", "0,0", 0.70710678 },
new object[] { "-1,0", "0,+1", "-0.5,0.5", 0.0 },
new object[] { "+1,-1", "+1,+1", "0,0", 1.0 },
new object[] { "+1,-1", "+1,+1", "1,0", 0.0 },
new object[] { "+1,-1", "+1,+1", "3,0", 2.0 },
};

[TestCaseSource(nameof(DistanceTestCases))]
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@jkalias jkalias Dec 27, 2023 •
edited
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I think the previous structure with TestCase was much better. My suggestion with the swapped scenarios was meant to be handled in the TestCase definition, not as a separate test function.

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Thanks for the comment.
Could you tell me why using TestCode is better than using TestCodeSource for this test?

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I find the whole new object[] a bit overkill, that's it. I guess it's more a matter of personal taste.

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Thanks for the comment.

it's more a matter of personal taste.

Could you show the reason?

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The reason for what exactly? I prefer compile-time checks and try to avoid object as much as possible

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@f-frhs f-frhs Jan 7, 2024 •
edited
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Thanks for telling the reasons.

Done in the commit cd80cf1.
I changed the test-code as you required. I'm not sure that the revised test-code helps the reader understand at a glance that parameters are kept intact except its order.

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Thank you. This is not what I meant, we can augment the existing tests with a reversed line

var line = new Line2D(Point2D.Parse(p1s), Point2D.Parse(p2s));
// existing test

var reversedLine = new Line2D(Point2D.Parse(p2s), Point2D.Parse(p1s));
// distance test with reversed line

This way you keep the TestCase cases at a minimum

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Thanks for showing the example closely.

It is not recommended to test 2 things in a single unit-test.
Or do you want to say that these 2 tests are equivalent because of the symmetry?

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It is not recommended to test 2 things in a single unit-test.

Fully agree

Or do you want to say that these 2 tests are equivalent because of the symmetry?

Basically yes

public void DistanceFromLineToPoint(string sp1, string sp2, string ps, double expectedDistance)
{
var line = new Line2D(Point2D.Parse(sp1), Point2D.Parse(sp2));
var p = Point2D.Parse(ps);

var actual = line.DistanceTo(p);
Assert.That(actual, Is.EqualTo(expectedDistance).Within(1e-6));
}

[TestCaseSource(nameof(DistanceTestCases))]
public void DistanceFromLineToPoint_SwappedP1sAndP2s(string sp1, string sp2, string ps, double expectedDistance)
{
var line = new Line2D(Point2D.Parse(sp2), Point2D.Parse(sp1)); // swapped
var p = Point2D.Parse(ps);

var actual = line.DistanceTo(p);
Assert.That(actual, Is.EqualTo(expectedDistance).Within(1e-6));
}

[TestCase("0,0", "10,10", "0,0", "10,10", true)]
[TestCase("0,0", "10,10", "0,0", "10,11", false)]
public void EqualityOperator(string p1s, string p2s, string p3s, string p4s, bool expected)
Expand Down
13 changes: 13 additions & 0 deletions src/Spatial/Euclidean/Line2D.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,19 @@ public static Line2D Parse(string startPointString, string endPointString)
return new Line2D(Point2D.Parse(startPointString), Point2D.Parse(endPointString));
}

/// <summary>
/// Returns the straight line Distance to the given point.
/// </summary>
/// <param name="p">the given point</param>
/// <returns>a distance measure</returns>
[Pure]
public double DistanceTo(Point2D p)
{
var closestPoint = ClosestPointTo(p, false); // this is Line2D, not LineSegment2D.
var result = closestPoint.DistanceTo(p);
return result;
}

/// <summary>
/// Returns the shortest line between this line and a point.
/// </summary>
Expand Down