map-snippet-5.js

/**
 * GetColorStops
 */
function getColorStops(data) {
    // Read all relevant values
    // and filter those that are not numbers
    const results = data.features
        .map(element => element.properties && element.properties.total ? element.properties.total[configuration.year] : 0)
        .filter(Number);

    // Define limits using quantile logic
    const limits = chroma
        .limits(results, 'q', 20 - 1)
        .filter((v, i, a) => a.indexOf(v) === i);

    // Create color scale
    const colorScale = chroma
        .scale(['#94CED9', '#116474'])
        .mode('lch')
        .colors(20);

    // Assign color to every country
    const stops = data.features.map(element => {
        let color = '#116474';
        if (element.properties.total && element.properties.total[configuration.year]) {
            for (let i = 0; i < limits.length; i++) {
                if (element.properties.total[configuration.year] >= limits[i]) {
                    color = colorScale[i];
                }
            }
        }
        return [element.properties.name, color];
    }).filter(element => typeof element[0] !== 'undefined');

    // Draw color scale
    drawColorScale(colorScale);

    return stops;
}