DateAxis


1   // $Id: DateAxis.java,v 1.11 2005/03/31 10:01:53 mike Exp $
2   
3   package org.faceless.graph2;
4   
5   import java.text.DateFormat  ;
6   import java.text.SimpleDateFormat  ;
7   import java.util.*;
8   
9   /**
10   * A subclass of Axis to be used for plotting date values. Dates are stored
11   * internally as doubles, and the two can be converted back and forth using
12   * the {@link #toDouble toDouble} and {@link #toDate toDate} methods.
13   * For example, to plot a number of dates on a {@link LineSeries} you could use
14   * code like the following:
15   *
16   * <pre class=example>
17   * AxesGraph graph = new AxesGraph();
18   * LineSeries series = new LineSeries("Dates");
19   * series.set(DateAxis.toDouble(date1), value1);
20   * series.set(DateAxis.toDouble(date2), value2);
21   * graph.setAxis(Axis.BOTTOM, new DateAxis());
22   * </pre>
23   * (here <i>date1</i> and <i>date2</i> are {@link Date} objects).
24   * Bars can also be plotted against a DateAxis - see the {@link GeneralBarSeries} API documentation for more info.
25   */
26  public class DateAxis extends Axis
27  {
28      private static final long MIDPOINT = 788940000;     // 25 years
29      private static final int SECDAYS=60*60*24;  // number of seconds in a day
30      private static final double mul=1000;   // used to convert doubles to days and vice versa.
31                              // Needed because of rounding error
32  
33      final DateFormat   f;
34      final boolean hasseconds, hashours, hasminutes, hasdays, hasmonths;
35      private final float mdensity;
36      private boolean barsatnoon;
37  
38      /**
39       * Create a new DateAxis with a format of "dd-MMM-yyyy"
40       */
41      public DateAxis()
42      {
43          this(new SimpleDateFormat  ("dd-MMM-yyyy"));
44      }
45  
46      /**
47       * Create a new DateAxis with the specified format
48       */
49      public DateAxis(DateFormat   format)
50      {
51          this(format, DENSITY_NORMAL);
52      }
53  
54      /**
55       * Create a new DateAxis with the specified format and density
56       *
57       * @param format how each date should be formatted
58       * @param density the density of the values on the axis - one of {@link Axis#DENSITY_NORMAL}, {@link Axis#DENSITY_SPARSE} or {@link Axis#DENSITY_MINIMAL}
59       */
60      public DateAxis(DateFormat   format, int density)
61      {
62          f = format;
63      long l = 1012820522000l;        // A random date that has hours, mins, seconds all non-zero.
64      String   s = f.format(new Date(l));
65      hasseconds = !s.equals(f.format(new Date(l+1000l)));
66      hasminutes = !s.equals(f.format(new Date(l+60000l)));
67      hashours =   !s.equals(f.format(new Date(l+3700000l)));
68      hasdays =    !s.equals(f.format(new Date(l+90100000l)));
69      hasmonths =  !s.equals(f.format(new Date(l+2678400000l)));
70      this.mdensity = density/10f;
71      }
72  
73      public String   format(double in)
74      {
75      return f.format(toDate(in));
76      }
77  
78      /**
79       * Convert a date to a double, so it can be stored internally.
80       * For example, to plot todays date on a Line Graph, you would do
81       * something like this:
82       * <pre class=example>
83       *   LineSeries data = new LineSeries("Dates");
84       *   Date today = new Date();
85       *   data.set(DateAxis.toDouble(today), 123.45);
86       * </pre>
87       * @see #toDate
88       */
89      public static final double toDouble(Date in)
90      {
91       return (double)(in.getTime()/mul)-MIDPOINT;
92      }
93  
94      /**
95       * Convert a double to a Date. The opposite of {@link #toDouble}. Use this
96       * to convert a double passed in to the {@link #format} method back to
97       * a Date.
98       */
99      public static final Date toDate(double in)
100     {
101         return new Date((long)((in+MIDPOINT)*mul));
102     }
103 
104     public double[] steps(double min, double max)
105     {
106         Date start = toDate(min);
107         Date end = toDate(max);
108     long diff = (long)(max-min);    // Difference in seconds
109     int step;
110 
111     if (hasseconds && diff<1800) {
112         step = 1;
113     } else if (hasminutes && diff<43200) {
114         step = 60;
115     } else if (hashours && diff<SECDAYS*7) {
116         step = 3600;
117     } else {
118         step = SECDAYS;
119     }
120 
121     List a = new ArrayList();
122 
123     String   oldt=null, t=null;
124     for (long i=((int)(min+step)/step)*step;i<=(int)(max+(step/2));i+=step)
125     {
126         Calendar c = new GregorianCalendar();
127         c.setTime(toDate((double)i));
128         if (step==SECDAYS && c.get(c.HOUR_OF_DAY)!=0) {
129             int h = c.get(c.HOUR_OF_DAY);
130         if (h>=22) h=24-h;
131         i-=(h*60*60);
132         c.setTime(toDate((double)i));
133         }
134 
135         boolean add=false;
136         if (hasseconds && diff<=15*mdensity) {      // 15 seconds - every seconds, tot<=15
137         add=true;
138         } else if (hasseconds && diff<=60*mdensity) {   // 1 minutes - every 5 seconds, tot<=12
139         if (c.get(c.SECOND)%5==0) add=true;
140         } else if (hasseconds && diff<=180*mdensity) {  // 3 minutes - every 15 seconds, tot<=12
141         if (c.get(c.SECOND)%15==0) add=true;
142         } else if (hasseconds && diff<=300*mdensity) {  // 5 minutes - every 30 seconds, tot<=10
143         if (c.get(c.SECOND)%30==0) add=true;
144         } else if (hasminutes && diff<=900*mdensity) {  // 15 minutes - every minute, tot<=15
145         if (c.get(c.SECOND)==0) add=true;
146         } else if (hasminutes && diff<=3600*mdensity) { // 1 hour - every 5 minutes, tot<=12
147         if (c.get(c.MINUTE)%5==0 && c.get(c.SECOND)==0) add=true;
148         } else if (hasminutes && diff<=7200*mdensity) { // 2 hours - every 10 minutes, tot<=12
149         if (c.get(c.MINUTE)%10==0 && c.get(c.SECOND)==0) add=true;
150         } else if (hasminutes && diff<=10800*mdensity) {    // 3 hours - every 15 minutes, tot<=12
151         if (c.get(c.MINUTE)%15==0 && c.get(c.SECOND)==0) add=true;
152         } else if (hasminutes && diff<=21600*mdensity) {    // 6 hours - every 30 minutes, tot<=12
153         if (c.get(c.MINUTE)%30==0 && c.get(c.SECOND)==0) add=true;
154         } else if (hashours && diff<=SECDAYS*mdensity) {    // 24 hours - every 2 hours, tot<=12
155         if (c.get(c.HOUR_OF_DAY)%2==0 && c.get(c.MINUTE)==0) add=true;
156         } else if (hashours && diff<4*SECDAYS*mdensity) {   // 96 hours (4 days) - every 6 hours, tot<15
157         if (c.get(c.HOUR_OF_DAY)%6==0 && c.get(c.MINUTE)==0) add=true;
158         } else if (hashours && diff<=6*SECDAYS*mdensity) {  // 144 hours (6 days) - ev. 12 hours, tot<=12
159         if (c.get(c.HOUR_OF_DAY)%12==0 && c.get(c.MINUTE)==0) add=true;
160         } else if (diff<15*SECDAYS*mdensity) {      // 2 weeks - every day, tot<=14
161         if (step>3600 || c.get(c.HOUR_OF_DAY)==0) add=true;
162         } else if (diff<32*SECDAYS*mdensity) {      // 1 month - every 2 days, tot<=15
163         if (c.get(c.DAY_OF_MONTH)%2==1 && c.get(c.HOUR_OF_DAY)==0) add=true;
164         } else if (diff<100*SECDAYS*mdensity) {     // 3 months - every sunday, tot<=13
165         if (c.get(c.DAY_OF_WEEK)==1 && c.get(c.HOUR_OF_DAY)==0) add=true;
166         } else if (diff<200*SECDAYS*mdensity) {     // 6 months - every 1st and 15th, tot<=12
167         if ((c.get(c.DAY_OF_MONTH)==1 || c.get(c.DAY_OF_MONTH)==15) && c.get(c.HOUR_OF_DAY)==0) add=true;
168         } else if (diff<367*SECDAYS*mdensity) {     // 1 year - every 1st, tot<=12
169         if (c.get(c.DAY_OF_MONTH)==1 && c.get(c.HOUR_OF_DAY)==0) add=true;
170         } else if (diff<730*SECDAYS*mdensity) {     // 2 years - 1st of every 2nd month, tot<=12
171             if (c.get(c.DAY_OF_MONTH)==1 && c.get(c.MONTH)%2==0 && c.get(c.HOUR_OF_DAY)==0) add=true;
172         } else if (diff<2190*SECDAYS*mdensity) {        // 3 years - 1st of every quarter, tot<=12
173             if (c.get(c.DAY_OF_MONTH)==1 && c.get(c.MONTH)%3==0 && c.get(c.HOUR_OF_DAY)==0) add=true;
174         } else if (diff<4400*SECDAYS*mdensity) {        // 6 years - 1st of jan/jul, tot<=12
175             if (c.get(c.DAY_OF_MONTH)==1 && c.get(c.MONTH)%6==0 && c.get(c.HOUR_OF_DAY)==0) add=true;
176         } else if (diff<5478*SECDAYS*mdensity) {        // 15 years - 1st of jan, tot<=15
177             if (c.get(c.DAY_OF_MONTH)==1 && c.get(c.MONTH)==0 && c.get(c.HOUR_OF_DAY)==0) add=true;
178         } else {                        // Over 15 years - Jan 1st every n years
179         int y = (int)(diff/(5478*SECDAYS*mdensity))+1;
180             if (c.get(c.DAY_OF_MONTH)==1 && c.get(c.MONTH)==0 && (c.get(c.YEAR)%y)==0 && c.get(c.HOUR_OF_DAY)==0) add=true;
181         }
182         if (add) {
183         oldt=t;
184             t = format((double)i);
185         if (!t.equals(oldt)) {
186             a.add(new Double  (i));
187         }
188         }
189     }
190 
191     // Add the first and last days of the specified period. If they're
192     // extremely close to calculated values from the block above,
193     // replace them (instead of adding new values).
194     //
195     if (a.size()<2) {
196         a.clear();
197         a.add(new Double  (min));
198         a.add(new Double  (max));
199     } else {
200         double first = ((Double  )a.get(0)).doubleValue();
201         double last = ((Double  )a.get(a.size()-1)).doubleValue();
202         if (first!=min) {
203             t = format(min);
204         String   t2 = format(first);
205         if (!t.equals(t2)) {
206             if ((first-min)/(max-min)>0.05/mdensity) {
207             a.add(0, new Double  (min));
208 //          throw new Error("first="+first+" min="+min+" max="+max+" first-min="+(first-min)+" max-min="+(max-min)+" f/m="+((first-min)/(max-min))+" den="+mdensity);
209             } else {
210             a.set(0, new Double  (min));
211             }
212         } else {
213             a.set(0, new Double  (first<min?first:min));
214         }
215         }
216         if (last!=max) {
217             t = format(max);
218         String   t2 = format(last);
219         if (!t.equals(t2)) {
220             if (((max-last)/(max-min))>0.05/mdensity) {
221             a.add(new Double  (max));
222             } else {
223             a.set(a.size()-1, new Double  (max));
224             }
225         } else {
226             a.set(a.size()-1, new Double  (last>max?last:max));
227         }
228         }
229     }
230 
231     // Return the list as a double[]
232     //
233     double[] out = new double[a.size()];
234     for (int i=0;i<out.length;i++) {
235         out[i] = ((Double  )a.get(i)).doubleValue();
236     }
237     return out;
238     }
239 
240     /**
241      * When plotting a {@link GeneralBarSeries} against a DateAxis, whether
242      * to center the bars on the tick, ie. midnight (false) or midway between the tick and
243      * the next tick, ie. noon (true). Typically you will want to set this method to
244      * true when plotting bars against lines that represent hour values, not just day values.
245      * When not plotting Bars, this method has no effect
246      *
247      * @param noon whether to center bars plotted against this axis at midday
248      */
249     public void setBarsAtNoon(boolean noon)
250     {
251         this.barsatnoon = noon;
252     }
253 
254     boolean getBarsAtNoon()
255     {
256         return barsatnoon;
257     }
258 }
259
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