Histogram.java
05/10/2010 00:11
/*************************************************************************
* Compilation: javac Histogram.java
*
* This data type supports simple client code to create dynamic
* histograms of the frequency of occurrence of values in [0, N).
* The frequencies are kept in an instance-variable array, and
* an instance variable max tracks the maximum frequency (for scaling).
*
* % java Histogram 50 1000000
*
*************************************************************************/
public class Histogram {
private final double[] freq; // freq[i] = # occurences of value i
private double max; // max frequency of any value
// Create a new histogram.
public Histogram(int N) {
freq = new double[N];
}
// Add one occurrence of the value i.
public void addDataPoint(int i) {
freq[i]++;
if (freq[i] > max) max = freq[i];
}
// draw (and scale) the histogram.
public void draw() {
StdDraw.setYscale(0, max);
StdStats.plotBars(freq);
}
// See Program 2.2.6.
public static void main(String[] args) {
int N = Integer.parseInt(args[0]); // number of coins
int T = Integer.parseInt(args[1]); // number of trials
// create the histogram
Histogram histogram = new Histogram(N+1);
for (int t = 0; t < T; t++) {
histogram.addDataPoint(Bernoulli.binomial(N));
}
// display using standard draw
StdDraw.setCanvasSize(500, 100);
histogram.draw();
}
}
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