statDensity

import std.stdio : writeln;
import std.algorithm : map;
import std.array : array;
import std.random : uniform;
import std.range : chain, iota, repeat, walkLength;

import ggplotd.aes : Aes;

auto xs = iota(0,100,1)
    .map!((i)=>uniform(0,0.75)+uniform(0.25,1))
    .array;

auto dens = statDensity( Aes!( typeof(xs), "x")( xs ) );
auto dim = dens.walkLength;
assertGreaterThan( dim, 1 );

// Test that grouping leads to longer (twice as long) result
auto cols = chain("a".repeat(50),"b".repeat(50) );
auto dens2 = statDensity( Aes!(typeof(cols), "colour", typeof(xs), "x")( cols, xs ) );
assertGreaterThan( dens2.walkLength, 1.9*dim );
assertLessThan( dens2.walkLength, 2.1*dim );

// Test that colour is passed through (merged)
assertEqual( dens2.front.colour.length, 1 );

// Test single point 
xs = [1];
dens = statDensity( Aes!( typeof(xs), "x")( xs ) );
assertEqual(dens.walkLength, 3);