一、前言
在衛星和高端傳感器的數據中。精通《設計模式》和算法,可以幫助您分析並做出更有力和知識淵博的決策,實現導航領域中搜索引擎的強大算法設計。
二、後端算法高級框架設計圖
三、相關設計模式的類名詞說明
1、蒙特卡羅樹搜索 - 圖形化模擬 Upper Confidence bound applied to Trees(UCT)
2、 calculation_time來控制時間
3、選舉(selection)是根據當前獲得所有子步驟的統計結果,選擇一個最優的子步驟。
4、擴展(expansion)在當前獲得的統計結果不足以計算出下一個步驟時,隨機選擇一個子步驟。
5、模擬(simulation)模擬決策過程,進入下一步。
6、反向傳播(Back-Propagation)根據決策的結果,計算對應路徑上統計記錄的值。
7、置信區間(confidence intervals)是指由樣本統計量所構造的總體參zhi數的估計區間,窄的置信區間比寬的置信區間能提供更多的有關總體參數的信息。越小的置信區間置信度就越高。
四、工具類設計
工具類:存在了某一類事物的工具方法的類。
工具類存在的包:工具包 tools 。
工具類起名:表示一類事物。比如:在tools包下的Sampler爲取樣器工具類。
該Sampler工具方法全部使用static修飾, 只需要使用工具類名調用即可。
五、設計代碼邏輯
註釋:由於公開,已經去掉中文說明。該類爲取樣器,進行數據的計算邏輯封裝。
package tools;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.Random;
import java.util.Set;
import jdk.internal.dynalink.beans.StaticClass;
public class Sampler {
private static Random rng = new Random(
Calendar.getInstance().getTimeInMillis() +
Thread.currentThread().getId());
public static Random getRandom() {
return rng;
}
public static boolean sampleCoin() {
return rng.nextBoolean();
}
public static double sampleBeta(double alpha, double beta) {
double x, y;
x = sampleGamma(alpha, 1);
y = sampleGamma(beta, 1);
return x / (x + y);
}
// Sample from the 1 - X where X ~ beta( alpha , beta)
public static double one_minus_sampleBeta(double alpha, double beta) {
double x, y;
x = sampleGamma(alpha, 1);
y = sampleGamma(beta, 1);
return y / (x + y);
}
public static long nextPoisson(double lambda) {
return (long) (-1.0 * Math.log(1.0 - rng.nextDouble() * 1.0) / lambda);
}
public static double nextExponential(double b) {
double randx;
double result;
randx = rng.nextDouble();
result = -1 * b * Math.log(randx);
return result;
}
public static double sampleGamma(double k, double theta) {
boolean accept = false;
if (k < 1) {
// Weibull algorithm
double c = (1 / k);
double d = ((1 - k) * Math.pow(k, (k / (1 - k))));
double u, v, z, e, x;
do {
u = rng.nextDouble();
v = rng.nextDouble();
z = -Math.log(u);
e = -Math.log(v);
x = Math.pow(z, c);
if ((z + e) >= (d + x)) {
accept = true;
}
} while (!accept);
return (x * theta);
} else {
// Cheng's algorithm
double b = (k - Math.log(4));
double c = (k + Math.sqrt(2 * k - 1));
double lam = Math.sqrt(2 * k - 1);
double cheng = (1 + Math.log(4.5));
double u, v, x, y, z, r;
do {
u = rng.nextDouble();
v = rng.nextDouble();
y = ((1 / lam) * Math.log(v / (1 - v)));
x = (k * Math.exp(y));
z = (u * v * v);
r = (b + (c * y) - x);
if ((r >= ((4.5 * z) - cheng)) ||
(r >= Math.log(z))) {
accept = true;
}
} while (!accept);
return (x * theta);
}
}
public static Double[] subSampleNaive(List<Double> samples, int m) {
int n = samples.size();
int nm = Math.min(m, n);
Double[] sub = new Double[nm];
if (nm == n) {
sub = samples.toArray(sub);
return sub;
}
for (int k = 0; k < nm; k++) {
int i = rng.nextInt(n);
Double aux = samples.get(k);
samples.set(k, samples.get(i));
samples.set(i, aux);
}
sub = samples.subList(0, nm).toArray(sub);
return sub;
}
public static Double[] subSample(List<Double> samples, int m) {
//System.out.println(samples.size() +" " + m);
int n = samples.size();
int nm = Math.min(m, n);
Double[] sub = new Double[nm];
if (nm == n) {
sub = samples.toArray(sub);
return sub;
}
if (m < n / 2) {
for (int k = 0; k < nm; k++) {
int i = rng.nextInt(n);
Double aux = samples.get(0);
samples.set(0, samples.get(i));
samples.set(i, aux);
}
sub = samples.subList(0, nm).toArray(sub);
} else {
for (int k = 0; k < n - nm; k++) {
int i = rng.nextInt(n);
Double aux = samples.get(0);
samples.set(0, samples.get(i));
samples.set(i, aux);
}
sub = samples.subList(n - nm, n).toArray(sub);
}
return sub;
}
}