The source code of Sharpe algorithm in backtesting system:
function returnAnalyze(totalAssets, profits, ts, te, period, yearDays) {
// force by days
period = 86400000
if (profits.length == 0) {
return null
}
var freeProfit = 0.03 // 0.04
var yearRange = yearDays * 86400000
var totalReturns = profits[profits.length - 1][1] / totalAssets
var annualizedReturns = (totalReturns * yearRange) / (te - ts)
// MaxDrawDown
var maxDrawdown = 0
var maxAssets = totalAssets
var maxAssetsTime = 0
var maxDrawdownTime = 0
var maxDrawdownStartTime = 0
var winningRate = 0
var winningResult = 0
for (var i = 0; i < profits.length; i++) {
if (i == 0) {
if (profits[i][1] > 0) {
winningResult++
}
} else {
if (profits[i][1] > profits[i - 1][1]) {
winningResult++
}
}
if ((profits[i][1] + totalAssets) > maxAssets) {
maxAssets = profits[i][1] + totalAssets
maxAssetsTime = profits[i][0]
}
if (maxAssets > 0) {
var drawDown = 1 - (profits[i][1] + totalAssets) / maxAssets
if (drawDown > maxDrawdown) {
maxDrawdown = drawDown
maxDrawdownTime = profits[i][0]
maxDrawdownStartTime = maxAssetsTime
}
}
}
if (profits.length > 0) {
winningRate = winningResult / profits.length
}
// trim profits
var i = 0
var datas = []
var sum = 0
var preProfit = 0
var perRatio = 0
var rangeEnd = te
if ((te - ts) % period > 0) {
rangeEnd = (parseInt(te / period) + 1) * period
}
for (var n = ts; n < rangeEnd; n += period) {
var dayProfit = 0.0
var cut = n + period
while (i < profits.length && profits[i][0] < cut) {
dayProfit += (profits[i][1] - preProfit)
preProfit = profits[i][1]
i++
}
perRatio = ((dayProfit / totalAssets) * yearRange) / period
sum += perRatio
datas.push(perRatio)
}
var sharpeRatio = 0
var volatility = 0
if (datas.length > 0) {
var avg = sum / datas.length;
var std = 0;
for (i = 0; i < datas.length; i++) {
std += Math.pow(datas[i] - avg, 2);
}
volatility = Math.sqrt(std / datas.length);
if (volatility !== 0) {
sharpeRatio = (annualizedReturns - freeProfit) / volatility
}
}
return {
totalAssets: totalAssets,
yearDays: yearDays,
totalReturns: totalReturns,
annualizedReturns: annualizedReturns,
sharpeRatio: sharpeRatio,
volatility: volatility,
maxDrawdown: maxDrawdown,
maxDrawdownTime: maxDrawdownTime,
maxAssetsTime: maxAssetsTime,
maxDrawdownStartTime: maxDrawdownStartTime,
winningRate: winningRate
}
}