var heatmap = new Chart(element, {
    type: 'heatmap',
    data: {
        xLabels: ['2014', '2015', '2016', '2017'],
        yLabels: ['Strength', 'Intelligence', 'Stamina', 'Spirit'],
        datasets: [{
            data: [{
                y: 0, // index of 'Strength'
                x: 0, // index of '2014'
                a: 0.5, // alpha of the color [0, 1]
                v: 500, // value
            }, {
                y: 2, // index of 'Stamina'
                x: 0, // index of '2014'
                a: 0.2, // alpha of the color [0, 1]
                v: 250, // value
            }, {
                 y: 1, // index of 'Intelligence'
                 x: 3, // index of '2017'
                 a: 1, // alpha of the color [0, 1]
                 v: 1000, // value
            }]
        }]
    },
    options: {
        yColors: [ // colors for each lines
            {r: 0,   g: 150, b: 136},
            {r: 255, g: 235, b: 59},
            {r: 255, g: 152, b: 0},
            {r: 244, g: 67,  b: 54}
        ],
    }
});