introducing histogram chart

xchart-demo/src/main/java/com/xeiam/xchart/demo/charts/bar/BarChart06.java

+/**
+ * Copyright 2011 - 2014 Xeiam LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.xeiam.xchart.demo.charts.bar;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+import com.xeiam.xchart.Chart;
+import com.xeiam.xchart.ChartBuilder;
+import com.xeiam.xchart.StyleManager.ChartType;
+import com.xeiam.xchart.StyleManager.LegendPosition;
+import com.xeiam.xchart.SwingWrapper;
+import com.xeiam.xchart.demo.charts.ExampleChart;
+
+/**
+ * Basic Bar Chart
+ * <p>
+ * Demonstrates the following:
+ * <ul>
+ * <li>Histogram
+ */
+public class BarChart06 implements ExampleChart {
+
+  public static void main(String[] args) {
+
+    ExampleChart exampleChart = new BarChart06();
+    Chart chart = exampleChart.getChart();
+    new SwingWrapper(chart).displayChart();
+  }
+
+  @Override
+  public Chart getChart() {
+
+    // Create Chart
+    Chart chart = new ChartBuilder().chartType(ChartType.Bar).width(800).height(600).title("Score Histogram").xAxisTitle("Score").yAxisTitle("Count").build();
+
+    chart.addSeries("histogram 1", getGaussianData(1000), 11, -30, 30);
+    chart.addSeries("histogram 2", getGaussianData(1000), 11, -30, 30);
+
+    // Customize Chart
+    chart.getStyleManager().setLegendPosition(LegendPosition.InsideNW);
+
+    return chart;
+  }
+
+  private List<Double> getGaussianData(int count) {
+
+    List<Double> data = new ArrayList<Double>(count);
+    Random r = new Random();
+    for (int i = 0; i < count; i++) {
+      // data.add(r.nextGaussian() * 10);
+      data.add(r.nextDouble() * 60 - 30);
+    }
+    return data;
+  }
+
+}

xchart/src/main/java/com/xeiam/xchart/Chart.java

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.Map;
 
 import com.xeiam.xchart.StyleManager.ChartTheme;
+import com.xeiam.xchart.internal.Histogram;
 import com.xeiam.xchart.internal.chartpart.ChartPainter;
 import com.xeiam.xchart.internal.style.Theme;
 
@@ -43,7 +44,6 @@ public class Chart {
   public Chart(int width, int height) {
 
     chartPainter = new ChartPainter(width, height);
-
   }
 
   /**
@@ -177,7 +177,7 @@ public class Chart {
   }
 
   /**
-   * Add a series to the chart using double arrays
+   * Add a series to the chart using int arrays
    * 
    * @param seriesName
    * @param xData the X-Axis data
@@ -190,7 +190,7 @@ public class Chart {
   }
 
   /**
-   * Add a series to the chart using double arrays with error bars
+   * Add a series to the chart using int arrays with error bars
    * 
    * @param seriesName
    * @param xData the X-Axis data
@@ -222,6 +222,23 @@ public class Chart {
     return chartPainter.getAxisPair().addSeries(seriesName, xDataNumber, yDataNumber, errorBarDataNumber);
   }
 
+  /**
+   * Add a series for a histogram
+   * 
+   * @param seriesName
+   * @param data
+   * @param numBins
+   * @param min
+   * @param max
+   * @return
+   */
+  public Series addSeries(String seriesName, Collection<? extends Number> data, int numBins, double min, double max) {
+
+    Histogram histogram1 = new Histogram(data, numBins, min, max);
+
+    return chartPainter.getAxisPair().addSeries(seriesName, histogram1.getxAxisData(), histogram1.getyAxisData(), null);
+  }
+
   /**
    * Set the chart title
    * 

xchart/src/main/java/com/xeiam/xchart/StyleManager.java

@@ -38,7 +38,7 @@ public class StyleManager {
    */
   public enum ChartType {
 
-    Line, Scatter, Area, Bar
+    Line, Scatter, Area, Bar, Histogram
   }
 
   public enum LegendPosition {
@@ -116,7 +116,7 @@ public class StyleManager {
   private Double xAxisMax;
   private Double yAxisMin;
   private Double yAxisMax;
-  private double axisTickSpaceRatio; 
+  private double axisTickSpaceRatio;
 
   // Chart Plot Area ///////////////////////////////
   private boolean isPlotGridLinesVisible;
@@ -850,11 +850,13 @@ public class StyleManager {
   }
 
   public void setAxisTickSpaceRatio(double axisTickSpaceRatio) {
+
     this.axisTickSpaceRatio = axisTickSpaceRatio;
   }
 
   public double getAxisTickSpaceRatio() {
-	return axisTickSpaceRatio;
+
+    return axisTickSpaceRatio;
   }
 
   // Chart Plot Area ///////////////////////////////

xchart/src/main/java/com/xeiam/xchart/internal/Histogram.java

+/**
+ * Copyright 2013 Xeiam LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.xeiam.xchart.internal;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+
+/**
+ * @author timmolter
+ */
+public class Histogram {
+
+  private final List<Double> xAxisData; // bin centers
+  private final List<Double> yAxisData; // frequency counts
+  private final Collection<? extends Number> originalData;
+  private final int numBins;
+  private final double min;
+  private final double max;
+
+  /**
+   * Constructor
+   */
+  public Histogram(Collection<? extends Number> data, int numBins, double min, double max) {
+
+    this.numBins = numBins;
+    this.originalData = data;
+    // Arrays.sort(data);
+    this.min = min;
+    this.max = max;
+    // this.min = data[0];
+    // this.max = data[data.length - 1];
+
+    double[] tempYAxisData = new double[numBins];
+    final double binSize = (max - min) / numBins;
+
+    // y axis data
+    Iterator<? extends Number> itr = data.iterator();
+    while (itr.hasNext()) {
+
+      int bin = (int) (((Double) itr.next() - min) / binSize); // changed this from numBins
+      if (bin < 0) { /* this data is smaller than min */
+      }
+      else if (bin >= numBins) { /* this data point is bigger than max */
+      }
+      else {
+        tempYAxisData[bin] += 1;
+      }
+    }
+    yAxisData = new ArrayList<Double>(numBins);
+    for (double d : tempYAxisData) {
+      yAxisData.add(new Double(d));
+    }
+
+    // x axis data
+    xAxisData = new ArrayList<Double>(numBins);
+    for (int i = 0; i < numBins; i++) {
+      xAxisData.add(((i * (max - min)) / numBins + min) + binSize / 2);
+    }
+  }
+
+  public List<Double> getxAxisData() {
+
+    return xAxisData;
+  }
+
+  public List<Double> getyAxisData() {
+
+    return yAxisData;
+  }
+
+  public Collection<? extends Number> getOriginalData() {
+
+    return originalData;
+  }
+
+  public int getNumBins() {
+
+    return numBins;
+  }
+
+  public double getMin() {
+
+    return min;
+  }
+
+  public double getMax() {
+
+    return max;
+  }
+
+}