🥷 High-performance polyline simplification library - port of simplify.js

Hi all I'm currently using SwiftSimplify to reduce the number of coordinates while running, I'm testing runs that go on for about 1 KM but after using Simplify and giving it about 20 points, all it does is return start and end coordinates.

Simplify is currently like this. SwiftSimplify.simplify(self.activityPolyline!, tolerance: 10, highQuality: false)

Giving it an array of coordinates like this: [(37.330075379999997, -122.02126848), (37.330058049999998, -122.02100589), (37.33000706, -122.02074717000001), (37.329941720000001, -122.02053031), (37.329871330000003, -122.0202987), (37.329823259999998, -122.02006170999999), (37.329705570000002, -122.01986866), (37.329525689999997, -122.01982409), (37.329339840000003, -122.01980544), (37.329133579999997, -122.0197871), (37.328938319999999, -122.01979684), (37.328738469999998, -122.01980584), (37.328532039999999, -122.0198032), (37.32833935, -122.01980995), (37.32814552, -122.01983108), (37.327952580000002, -122.01982651), (37.327758189999997, -122.01980315), (37.327560220000002, -122.01974095), (37.327370989999999, -122.01972170000001), (37.327185819999997, -122.01971872), (37.326979710000003, -122.01972916)]

After simplify I get this: [(37.330075379999997, -122.02126848), (37.326979710000003, -122.01972916)]

What am I doing wrong? The location manager is currently configured as follows: locationManager.activityType = .fitness locationManager.desiredAccuracy = kCLLocationAccuracyKilometer locationManager.distanceFilter = 20

Appreciate the help.

This PR changes all public interfaces for library to accept parameters with generic types conforming Point2DRepresentable protocol, which makes return type of the function SwiftSimplify.simplify(_:tolerance:highestQuality:) equals the type of the first parameter points.

• Use implicit returns
• Remove unnecessary explicit references to self
• Use enum instead of struct for namespacing to restrict initialization
• Update .gitignore file
• Add resources to test target in Package.swift
• fileprivate -> private

Referencing instance method 'simplify(tolerance:highestQuality:)' on 'Array' requires the types 'CLLocationCoordinate2D' and 'Point2DRepresentable' be equivalent

When the lib is added to a project via CocoaPods, the extensions on CLLocationCoordinate2D etc are not visible.

After installing the pod I tried calling it like I would another pod (say like Alamofire) and the methods were not accessible. It did work, however, if I simply added it to my project.

In func simplifyRadialDistance, it use force unwrap var prevPoint: T = points.first! and var point: T = points[1]. This would cause crash when input parameter points is just 0 or 1 count. Although I add something like guard line.count > 1 before use SwiftSimplify.simplify to avoid crash, hope this check could add, thank you very much.

Add simple SimplifyValue protocol to add support to simplify any type which supports this protocol. CGPoint and CLLocationCoordinate2D support this protocol already

If you do calculations based on latitude/longitude, then:

1. You get different scales on the x/y-axis which leads to weird simplification logic
2. You can't relate to the tolerance value

The solution would be to e.g. convert it to MKMapPoints before simplification and if the data points are MKMapPoints you could interpret the tolerance value as meters and it would be both correct (1 above) and use a tolerance that you can relate to (2 above).

You show time in milliseconds /* Returns the current CoreAnimation absolute time. This is the result of

• calling mach_absolute_time () and converting the units to seconds. */

@available(iOS 2.0, *) public func CACurrentMediaTime() -> CFTimeInterval

I added the property isMandatory to Point2DRepresentable. This allows to mark certain points as mandatory - so that regardless of the simplification process, they're always included in the result.

I'm not sure it's the most efficient way of doing this - for our use case it works very well: We're optimisation a large collection of coordinates (x: latitude, y: longitude) and some coordinates must be included in the optimised collection (i.e. isMandatory = true).

SwiftSimplify/Package.swift The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.5.99.

Should we an easy fix.

Hi, I'm using the pods and when I try to simplify my [CCLocation2D] consisting in 2125 points the function return my an array with only 2 values.

I'm doing this:

let simplifiedCoordinates = SwiftSimplify.simplify(coordinates!, tolerance: 1.75) (I've tried also with 1 tolerance, but nothing change)

https://github.com/malcommac/SwiftSimplify/blob/95856a3fce40e4a77f51050d5b6c1f59da072355/Sources/SwiftSimplify/Point2DRepresentable.swift#L54

These appear to be returning a standard Pythagoras result, but the result is not square rooted. AFAIK this is not meant to be the case but I haven't had time to dig (I only know the DP algorithm at a distance).

If this is meant to be a linear distance, it looks like it needs to be square rooted. Else it might help to modify the function names to indicate that this is a squared result - otherwise it looks like a straightforward distance calculation function.

For my work I needed to keep array copies at a minimum (dealing with arrays with 100s of 1000s of points) and modified the code here to include an ArraySlice API for dealing with large subsets of the big arrays

Any interest in a pull request for that API? I wasn't sure how to handle the highestQuality parameter - in my use case I took it out to prevent an array copy but I think the simplifyRadialDistance method could be overloaded to slice the input array even thinner.