[Java]数据分析--数据可视化
时间序列
需求：将⼀组字符顺序添加到时间序列中
实现：定义时间序列类TimeSeries，包含静态类Entry表⽰序列类中的各项，以及add，get，iterator，entry⽅法TimeSeries.java
1import java.util.ArrayList;
2import java.util.Iterator;
3import java.util.Map;
4import java.util.TreeMap;
5import urrent.TimeUnit;
6
7public class TimeSeries<T> implements Iterable<TimeSeries.Entry> {
8private final Map<Long,T> map = new TreeMap();
9
10public void add(long time, T event) {
11        map.put(time, event);
12try {
13            TimeUnit.MICROSECONDS.sleep(1);  // 0.000001 sec delay
14        } catch(InterruptedException e) {
15            println(e);
16        }
17    }
18
19public T get(long time) {
(time);
21    }
22
23    ArrayList getList() {
24        ArrayList<Entry> list = new ArrayList();
25for (Entry entry : this) {
26            list.add(entry);
27        }
28return list;
29    }
30
31public int size() {
32return map.size();
33    }
34
35    @Override
36public Iterator iterator() {
37return new Iterator() { // anonymous inner class
38private final Iterator it = map.keySet().iterator();
39
40            @Override
41public boolean hasNext() {
42return it.hasNext();
43            }
44
45            @Override
46public Entry<T> next() {
47long time = (();
48                T event = (time);
49return new Entry(time, event);
50            }
51        };
52    }
53
54public static class Entry<T> {
55private final Long time;
java开发可视化界面
56private final T event;
57
58public Entry(long time, T event) {
59this.time = time;
60this.event = event;
61        }
62
63public long getTime() {
64return time;
65        }
66
67public T getEvent() {
68return event;
69        }
70
71        @Override
72public String toString() {
73return String.format("(%d, %s)", time, event);
74        }
75    }
76 }
View Code
TimeSeriesTester.java
1import java.util.ArrayList;
2
3public class TimeSeriesTester {
4final static String[] EVENTS = {"It", "was", "the", "best", "of", "times"};
5
6public static void main(String[] args) {
7        TimeSeries<String> series = new TimeSeries();
8        load(series);
9
10for (TimeSeries.Entry<String> entry : series) {
11long time = Time();
12            String event = Event();
13            System.out.printf("%16d: %s%n", time, event);
14        }
15
16        ArrayList list = List();
17        System.out.printf("(3) = %s%n", (3));
18    }
19
20static void load(TimeSeries<String> series) {
21for (String event : EVENTS) {
22            series.add(System.currentTimeMillis(), event);
23        }
24    }
25 }
View Code
移动平均
需求：实现⼀个序列，其值是原始序列连续⽚段的平均值
实现：定义移动平均类MovingAverage，继承TimeSeries，同时实现根据原始序列和⽚段长度⽣成新序列的构造⽅法，tmp每次计算保存⼀个⽚段，sum计算⽚段元素之和，最后把平均值添加到序列中
注意
如原始序列有8个元素，⽚段长度为3，则新序列长度为 8-8%3=6
对于a=b=c，先执⾏b=c，再执⾏a=b
tmp不是每次全部更新，替换⼀个元素即可，求和后i⾃增
MovingAverage.java
1import java.util.Iterator;
2
3public class MovingAverage extends TimeSeries<Double> {
4private final TimeSeries parent;
5private final int length;
6
7public MovingAverage(TimeSeries parent, int length) {
8this.parent = parent;
9this.length = length;
10if (length > parent.size()) {
11throw new IllegalArgumentException("That's too long.");
12        }
13
14double[] tmp = new double[length];  // temp array to compute averages
15double sum = 0;
16int i=0;
17        Iterator it = parent.iterator();
18for (int j = 0; j < length; j++) {
19            sum += tmp[i++] = nextValue(it);
20        }
21this.add(System.currentTimeMillis(), sum/length);
22
23while (it.hasNext()) {
24            sum -= tmp[i%length];
25            sum += tmp[i++%length] = nextValue(it);
26this.add(System.currentTimeMillis(), sum/length);
27        }
28    }
29
30/*  Returns the double value in the Entry currently located by it.
31*/
32private static double nextValue(Iterator it) {
33        TimeSeries.Entry<Double> entry = (TimeSeries.();
Event();
35    }
36 }
View Code
MovingAverageTester.java
1public class MovingAverageTester {
2static final double[] DATA = {20, 25, 21, 26, 28, 27, 29, 31};
3
4public static void main(String[] args) {
5        TimeSeries<Double> series = new TimeSeries();
6for (double x : DATA) {
7            series.add(System.currentTimeMillis(), x);
8        }
9        System.out.List());
10
11        TimeSeries<Double> ma3 = new MovingAverage(series, 3);
12        System.out.List());
13
14        TimeSeries<Double> ma5 = new MovingAverage(series, 5);
15        System.out.List());
16    }
17 }
View Code
指数分布
需求：模拟输出客服接电话的时间，两次电话之间的时间为指数分布，已知平均8⼩时接到120个电话实现：平均等待时间为4分钟，密度参数为0.25，⽣成随机数后代⼊指数分布公式，即得到时间
1import java.util.Random;
2
3public class ArrivalTimesTester {
4static final Random random = new Random();
5static final double LAMBDA = 0.25;
6
7static double time() {
8double p = Double();
9return -Math.log(1 - p)/LAMBDA;
10    }
11
12public static void main(String[] args) {
13double sum=0;
14for (int i = 0; i < 8; i++) {
15            System.out.println(time());
16            sum += time();
17        }
18        System.out.println("\n");
19        System.out.println(sum/8);
20    }
21 }
View Code

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