number-to-color.js

// given an array of numbers scale each value so that
// the smallest is newMin and the largest is newMax
// while maintaining the ratio of distances between values
function stretchRange(nums, newMin, newMax) {
	var min = Math.min.apply(Math, nums);
	var max = Math.max.apply(Math, nums);
	var range = max - min;
	var newRange = newMax - newMin;
	var scaled = [];
	for (var i = 0; i < nums.length; i++) {
		var fractionOfRange = (nums[i] - min) / range;
		scaled.push(newMin + newRange * fractionOfRange);
	}
	return scaled;
}

// Pass a number and the range that this number falls in.
// Returns a CSS color string with a hue representing your number in your range.
function numToHue(num, min, max) {
	var hue = Math.round(stretchRange([min || 0, num, max || 1], 0, 359)[1]);
	var saturation = 43;
	var lightness = 62;
	return 'hsl(' + hue + ',' + saturation + '%,' + lightness + '%)';
}

// Pass a number and the range that this number falls in.
// Returns a CSS color string with a shade from black to white representing your number in your range.
function numToShade(num, min, max) {
	var rgb = Math.round(stretchRange([min || 0, num, max || 1], 0, 255)[1]);
	return {
		background: 'rgb(' + rgb + ',' + rgb + ',' + rgb + ')',
		foreground: rgb > 255 / 2 ? 'black' : 'white'
	};
}