Merge branch 'develop'

README.md

@@ -102,3 +102,4 @@ Please report any bugs or submit feature requests to [XChart's Github issue trac
 
 ## Donations
 1PrZHiJorAw7RQrjP9CJgtPuqr6fU65PKt
+

pom.xml

@@ -4,7 +4,7 @@
 
 	<groupId>com.xeiam.xchart</groupId>
 	<artifactId>xchart-parent</artifactId>
-	<version>2.3.2-SNAPSHOT</version>
+	<version>2.3.3-SNAPSHOT</version>
 	<packaging>pom</packaging>
 	<name>XChart Parent</name>
 	<description>Basic Charts for Java Applications</description>

xchart-demo/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>com.xeiam.xchart</groupId>
 		<artifactId>xchart-parent</artifactId>
-		<version>2.3.2-SNAPSHOT</version>
+		<version>2.3.3-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>xchart-demo</artifactId>
@@ -17,7 +17,7 @@
 		<dependency>
 			<groupId>com.xeiam.xchart</groupId>
 			<artifactId>xchart</artifactId>
-			<version>2.3.2-SNAPSHOT</version>
+			<version>2.3.3-SNAPSHOT</version>
 		</dependency>
 	</dependencies>
 

xchart-demo/src/main/java/com/xeiam/xchart/demo/XChartDemo.java

@@ -38,6 +38,8 @@ import com.xeiam.xchart.demo.charts.bar.BarChart02;
 import com.xeiam.xchart.demo.charts.bar.BarChart03;
 import com.xeiam.xchart.demo.charts.bar.BarChart04;
 import com.xeiam.xchart.demo.charts.bar.BarChart05;
+import com.xeiam.xchart.demo.charts.bar.BarChart06;
+import com.xeiam.xchart.demo.charts.bar.BarChart07;
 import com.xeiam.xchart.demo.charts.date.DateChart01;
 import com.xeiam.xchart.demo.charts.date.DateChart02;
 import com.xeiam.xchart.demo.charts.date.DateChart03;
@@ -78,8 +80,8 @@ public class XChartDemo extends JPanel implements TreeSelectionListener {
   private XChartPanel chartPanel;
 
   /** real-time chart example */
-  final RealtimeChart01 realtimeChart01 = new RealtimeChart01();;
-  final RealtimeChart02 realtimeChart02 = new RealtimeChart02();;
+  final RealtimeChart01 realtimeChart01 = new RealtimeChart01();
+  final RealtimeChart02 realtimeChart02 = new RealtimeChart02();
   Timer timer = new Timer();
 
   /**
@@ -192,7 +194,7 @@ public class XChartDemo extends JPanel implements TreeSelectionListener {
     defaultMutableTreeNode = new DefaultMutableTreeNode(new ChartInfo("AreaChart02 - Null Y-Axis Data Points", new AreaChart02().getChart()));
     category.add(defaultMutableTreeNode);
 
-    // First category
+    // Line category
     category = new DefaultMutableTreeNode("Line Charts");
     top.add(category);
 
@@ -249,6 +251,12 @@ public class XChartDemo extends JPanel implements TreeSelectionListener {
     defaultMutableTreeNode = new DefaultMutableTreeNode(new ChartInfo("BarChart05 - GGPlot2 Theme", new BarChart05().getChart()));
     category.add(defaultMutableTreeNode);
 
+    defaultMutableTreeNode = new DefaultMutableTreeNode(new ChartInfo("BarChart06 - Histogram Overlapped", new BarChart06().getChart()));
+    category.add(defaultMutableTreeNode);
+
+    defaultMutableTreeNode = new DefaultMutableTreeNode(new ChartInfo("BarChart07 - Histogram Not Overlapped", new BarChart07().getChart()));
+    category.add(defaultMutableTreeNode);
+
     // Theme category
     category = new DefaultMutableTreeNode("Chart Themes");
     top.add(category);

xchart-demo/src/main/java/com/xeiam/xchart/demo/charts/bar/BarChart04.java

@@ -47,7 +47,7 @@ public class BarChart04 implements ExampleChart {
     // Create Chart
     Chart chart = new ChartBuilder().chartType(ChartType.Bar).width(800).height(600).title("XFactor vs. Age").xAxisTitle("Age").yAxisTitle("XFactor").build();
     chart.addSeries("female", new double[] { 10, 20, 30, 40, 50 }, new double[] { 50, 10, 20, 40, 35 });
-    chart.addSeries("male", new double[] { 10, 20, 30, 50 }, new double[] { 40, 30, 20, 60 });
+    chart.addSeries("male", new double[] { 10, 20, 30, 40, 50 }, new double[] { 40, 30, 20, 0, 60 });
 
     chart.getStyleManager().setYAxisMin(5);
     chart.getStyleManager().setYAxisMax(70);

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.Histogram;
+import com.xeiam.xchart.StyleManager.ChartType;
+import com.xeiam.xchart.StyleManager.LegendPosition;
+import com.xeiam.xchart.SwingWrapper;
+import com.xeiam.xchart.demo.charts.ExampleChart;
+
+/**
+ * Histogram Overlapped
+ * <p>
+ * Demonstrates the following:
+ * <ul>
+ * <li>Histogram
+ * <li>Bar Chart styles - overlapped, bar width
+ */
+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("Mean").yAxisTitle("Count").build();
+
+    Histogram histogram1 = new Histogram(getGaussianData(10000), 30, -30, 30);
+    Histogram histogram2 = new Histogram(getGaussianData(5000), 30, -30, 30);
+    chart.addSeries("histogram 1", histogram1.getxAxisData(), histogram1.getyAxisData());
+    chart.addSeries("histogram 2", histogram2.getxAxisData(), histogram2.getyAxisData());
+
+    // Customize Chart
+    chart.getStyleManager().setLegendPosition(LegendPosition.InsideNW);
+    chart.getStyleManager().setBarWidthPercentage(.96);
+    chart.getStyleManager().setBarsOverlapped(true);
+
+    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-demo/src/main/java/com/xeiam/xchart/demo/charts/bar/BarChart07.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.Histogram;
+import com.xeiam.xchart.StyleManager.ChartType;
+import com.xeiam.xchart.StyleManager.LegendPosition;
+import com.xeiam.xchart.SwingWrapper;
+import com.xeiam.xchart.demo.charts.ExampleChart;
+
+/**
+ * Histogram Not Overlapped
+ * <p>
+ * Demonstrates the following:
+ * <ul>
+ * <li>Histogram
+ * <li>Bar Chart styles - not overlapped, bar width
+ * <li>Integer data values
+ */
+public class BarChart07 implements ExampleChart {
+
+  public static void main(String[] args) {
+
+    ExampleChart exampleChart = new BarChart07();
+    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("Mean").yAxisTitle("Count").build();
+
+    Histogram histogram1 = new Histogram(getGaussianData(1000), 10, -30, 30);
+    chart.addSeries("histogram 1", histogram1.getxAxisData(), histogram1.getyAxisData());
+    Histogram histogram2 = new Histogram(getGaussianData(1000), 10, -30, 30);
+    chart.addSeries("histogram 2", histogram2.getxAxisData(), histogram2.getyAxisData());
+
+    // Customize Chart
+    chart.getStyleManager().setLegendPosition(LegendPosition.InsideNW);
+    chart.getStyleManager().setBarWidthPercentage(.96);
+
+    return chart;
+  }
+
+  private List<Integer> getGaussianData(int count) {
+
+    List<Integer> data = new ArrayList<Integer>(count);
+    Random r = new Random();
+    for (int i = 0; i < count; i++) {
+      data.add((int) (r.nextGaussian() * 10));
+      // data.add(r.nextDouble() * 60 - 30);
+    }
+    return data;
+  }
+
+}

xchart-demo/src/main/java/com/xeiam/xchart/demo/charts/line/LineChart06.java

@@ -46,11 +46,11 @@ public class LineChart06 implements ExampleChart {
   @Override
   public Chart getChart() {
 
-    double[] xData = new double[] { 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
+    int[] xData = new int[] { 0, 1, 2, 3, 4, 5, 6 };
 
-    double[] yData1 = new double[] { 100, 100, 100, 60, 10, 10, 10 };
+    int[] yData1 = new int[] { 100, 100, 100, 60, 10, 10, 10 };
 
-    double[] errdata = new double[] { 50, 20, 10, 52, 9, 2, 1 };
+    int[] errdata = new int[] { 50, 20, 10, 52, 9, 2, 1 };
 
     Chart chart = new Chart(800, 600);
 

xchart/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>com.xeiam.xchart</groupId>
 		<artifactId>xchart-parent</artifactId>
-		<version>2.3.2-SNAPSHOT</version>
+		<version>2.3.3-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>xchart</artifactId>

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

@@ -43,7 +43,6 @@ public class Chart {
   public Chart(int width, int height) {
 
     chartPainter = new ChartPainter(width, height);
-
   }
 
   /**
@@ -176,6 +175,52 @@ public class Chart {
     return chartPainter.getAxisPair().addSeries(seriesName, xDataNumber, yDataNumber, errorBarDataNumber);
   }
 
+  /**
+   * Add a series to the chart using int arrays
+   * 
+   * @param seriesName
+   * @param xData the X-Axis data
+   * @param xData the Y-Axis data
+   * @return A Series object that you can set properties on
+   */
+  public Series addSeries(String seriesName, int[] xData, int[] yData) {
+
+    return addSeries(seriesName, xData, yData, null);
+  }
+
+  /**
+   * Add a series to the chart using int arrays with error bars
+   * 
+   * @param seriesName
+   * @param xData the X-Axis data
+   * @param xData the Y-Axis data
+   * @param errorBars the error bar data
+   * @return A Series object that you can set properties on
+   */
+  public Series addSeries(String seriesName, int[] xData, int[] yData, int[] errorBars) {
+
+    List<Double> xDataNumber = null;
+    if (xData != null) {
+      xDataNumber = new ArrayList<Double>();
+      for (int d : xData) {
+        xDataNumber.add(new Double(d));
+      }
+    }
+    List<Double> yDataNumber = new ArrayList<Double>();
+    for (int d : yData) {
+      yDataNumber.add(new Double(d));
+    }
+    List<Double> errorBarDataNumber = null;
+    if (errorBars != null) {
+      errorBarDataNumber = new ArrayList<Double>();
+      for (int d : errorBars) {
+        errorBarDataNumber.add(new Double(d));
+      }
+    }
+
+    return chartPainter.getAxisPair().addSeries(seriesName, xDataNumber, yDataNumber, errorBarDataNumber);
+  }
+
   /**
    * Set the chart title
    * 

xchart/src/main/java/com/xeiam/xchart/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;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+
+/**
+ * This class can be used to create histogram data for histogram bar charts
+ * 
+ * @author timmolter
+ */
+public class Histogram {
+
+  private List<Double> xAxisData; // bin centers
+  private List<Double> yAxisData; // frequency counts
+  private final Collection<? extends Number> originalData;
+  private final int numBins;
+  private final double min;
+  private final double max;
+
+  /**
+   * Constructor
+   * 
+   * @param data
+   * @param numBins
+   */
+  public Histogram(Collection<? extends Number> data, int numBins) {
+
+    this.numBins = numBins;
+    this.originalData = data;
+
+    List<Double> dataAsList = new ArrayList<Double>();
+    Iterator<? extends Number> itr = data.iterator();
+    while (itr.hasNext()) {
+      dataAsList.add(((Number) itr.next()).doubleValue());
+    }
+    Collections.sort(dataAsList);
+    this.min = dataAsList.get(0);
+    this.max = dataAsList.get(dataAsList.size() - 1);
+
+    init();
+  }
+
+  /**
+   * Constructor
+   * 
+   * @param data
+   * @param numBins
+   * @param min
+   * @param max
+   */
+  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];
+
+    init();
+  }
+
+  private void init() {
+
+    double[] tempYAxisData = new double[numBins];
+    final double binSize = (max - min) / numBins;
+
+    // y axis data
+    Iterator<? extends Number> itr = originalData.iterator();
+    while (itr.hasNext()) {
+
+      int bin = (int) ((((Number) itr.next()).doubleValue() - 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;
+  }
+
+}

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

@@ -127,6 +127,10 @@ public class StyleManager {
   private Color plotGridLinesColor;
   private Stroke plotGridLinesStroke;
 
+  // Bar Charts ///////////////////////////////
+  private double barWidthPercentage;
+  private boolean barsOverlapped;
+
   // Error Bars ///////////////////////////////
   private Color errorBarsColor;
 
@@ -205,6 +209,10 @@ public class StyleManager {
     plotGridLinesColor = theme.getPlotGridLinesColor();
     plotGridLinesStroke = theme.getPlotGridLinesStroke();
 
+    // Bar Charts ///////////////////////////////
+    barWidthPercentage = theme.getBarWidthPercentage();
+    barsOverlapped = theme.barsOverlapped();
+
     // Error Bars ///////////////////////////////
     errorBarsColor = theme.getErrorBarsColor();
 
@@ -850,10 +858,12 @@ public class StyleManager {
   }
 
   public void setAxisTickSpaceRatio(double axisTickSpaceRatio) {
+
     this.axisTickSpaceRatio = axisTickSpaceRatio;
   }
 
   public double getAxisTickSpaceRatio() {
+
     return axisTickSpaceRatio;
   }
 
@@ -964,6 +974,38 @@ public class StyleManager {
     return plotGridLinesStroke;
   }
 
+  // Bar Charts ///////////////////////////////
+
+  /**
+   * set the width of a single bar in a bar chart. full width is 100%, i.e. 1.0
+   * 
+   * @param barWidthPercentage
+   */
+  public void setBarWidthPercentage(double barWidthPercentage) {
+
+    this.barWidthPercentage = barWidthPercentage;
+  }
+
+  public double getBarWidthPercentage() {
+
+    return barWidthPercentage;
+  }
+
+  /**
+   * set whether or no bars are overlapped. Otherwise they are places side-by-side
+   * 
+   * @param barsOverlapped
+   */
+  public void setBarsOverlapped(boolean barsOverlapped) {
+
+    this.barsOverlapped = barsOverlapped;
+  }
+
+  public boolean barsOverlapped() {
+
+    return barsOverlapped;
+  }
+
   // Error Bars ///////////////////////////////
 
   /**

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

@@ -29,6 +29,8 @@ import javax.swing.JPanel;
  */
 public class SwingWrapper {
 
+  private String windowTitle = "XChart";
+
   private List<Chart> charts = new ArrayList<Chart>();
   private int numRows;
   private int numColumns;
@@ -70,13 +72,25 @@ public class SwingWrapper {
     this.numColumns = numColumns;
   }
 
+  /**
+   * Display the chart in a Swing JFrame
+   * 
+   * @param windowTitle the title of the window
+   */
+  public JFrame displayChart(String windowTitle) {
+
+    this.windowTitle = windowTitle;
+
+    return displayChart();
+  }
+
   /**
    * Display the chart in a Swing JFrame
    */
   public JFrame displayChart() {
 
     // Create and set up the window.
-    final JFrame frame = new JFrame("XChart");
+    final JFrame frame = new JFrame(windowTitle);
 
     // Schedule a job for the event-dispatching thread:
     // creating and showing this application's GUI.
@@ -98,13 +112,26 @@ public class SwingWrapper {
     return frame;
   }
 
+  /**
+   * Display the charts in a Swing JFrame
+   * 
+   * @param windowTitle the title of the window
+   * @return the JFrame
+   */
+  public JFrame displayChartMatrix(String windowTitle) {
+
+    this.windowTitle = windowTitle;
+
+    return displayChartMatrix();
+  }
+
   /**
    * Display the chart in a Swing JFrame
    */
   public JFrame displayChartMatrix() {
 
     // Create and set up the window.
-    final JFrame frame = new JFrame("XChart");
+    final JFrame frame = new JFrame(windowTitle);
 
     // Schedule a job for the event-dispatching thread:
     // creating and showing this application's GUI.

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

@@ -245,7 +245,7 @@ public class XChartPanel extends JPanel {
   }
 
   /**
-   * update a series by only updating the Y-Axis data. The X-Axis data will is automatically generated as a list of increasing Integers starting from 1 and ending at the size of the new Y-Axis data
+   * update a series by only updating the Y-Axis data. The X-Axis data will be automatically generated as a list of increasing Integers starting from 1 and ending at the size of the new Y-Axis data
    * list.
    * 
    * @param seriesName
@@ -275,7 +275,7 @@ public class XChartPanel extends JPanel {
   }
 
   /**
-   * update a series by only updating both the X-Axis and Y-Axis data
+   * update a series by updating both the X-Axis and Y-Axis data
    * 
    * @param seriesName
    * @param newYData

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

@@ -15,7 +15,6 @@
  */
 package com.xeiam.xchart.internal;
 
-
 /**
  * @author timmolter
  */
@@ -35,10 +34,10 @@ public class Utils {
    * @param tickSpace
    * @return
    */
-  public static int getTickStartOffset(int workingSpace, int tickSpace) {
+  public static double getTickStartOffset(double workingSpace, double tickSpace) {
 
-    int marginSpace = workingSpace - tickSpace;
-    return (int) (marginSpace / 2.0);
+    double marginSpace = workingSpace - tickSpace;
+    return marginSpace / 2.0;
   }
 
   public static double pow(double base, int exponent) {

xchart/src/main/java/com/xeiam/xchart/internal/chartpart/AxisPair.java

@@ -102,9 +102,9 @@ public class AxisPair implements ChartPart {
       series = new Series(seriesName, xData, xAxis.getAxisType(), yData, yAxis.getAxisType(), errorBars, seriesColorMarkerLineStyleCycler.getNextSeriesColorMarkerLineStyle());
     }
     else { // generate xData
-      List<Number> generatedXData = new ArrayList<Number>();
+      List<Double> generatedXData = new ArrayList<Double>();
       for (int i = 1; i < yData.size() + 1; i++) {
-        generatedXData.add(i);
+        generatedXData.add((double) i);
       }
       xAxis.setAxisType(AxisType.Number);
       yAxis.setAxisType(AxisType.Number);

xchart/src/main/java/com/xeiam/xchart/internal/chartpart/AxisTick.java

@@ -152,7 +152,7 @@ public class AxisTick implements ChartPart {
     return axisTickLabels;
   }
 
-  public List<Integer> getTickLocations() {
+  public List<Double> getTickLocations() {
 
     return gridStep.getTickLocations();
   }

xchart/src/main/java/com/xeiam/xchart/internal/chartpart/AxisTickBarChartCalculator.java

@@ -53,23 +53,34 @@ public class AxisTickBarChartCalculator extends AxisTickCalculator {
     int tickSpace = (int) (styleManager.getAxisTickSpaceRatio() * workingSpace); // in plot space
 
     // where the tick should begin in the working space in pixels
-    int margin = Utils.getTickStartOffset(workingSpace, tickSpace); // in plot space double gridStep = getGridStepForDecimal(tickSpace);
+    double margin = Utils.getTickStartOffset(workingSpace, tickSpace); // in plot space double gridStep = getGridStepForDecimal(tickSpace);
 
     // get all categories
     List<Object> categories = new ArrayList<Object>();
+
+    Series firstSeries = chartPainter.getAxisPair().getSeriesMap().values().iterator().next(); // we use this to check all series have the exact same length and values
     for (Series series : chartPainter.getAxisPair().getSeriesMap().values()) {
 
+      Iterator<?> firstSeriesItr = firstSeries.getXData().iterator();
       Iterator<?> xItr = series.getXData().iterator();
       while (xItr.hasNext()) {
+
+        // check matching
+        Object next = xItr.next();
+        Object firstSeriesNext = firstSeriesItr.next();
+        if (!firstSeriesNext.equals(next)) {
+          throw new IllegalArgumentException("X-Axis data must exactly match all other Series X-Axis data for Bar Charts!!");
+        }
+
         Object x = null;
         if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.Number) {
-          x = xItr.next();
+          x = next;
         }
         else if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.Date) {
-          x = (double) (((Date) xItr.next()).getTime());
+          x = (double) (((Date) next).getTime());
         }
         else if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.String) {
-          x = xItr.next();
+          x = next;
         }
         if (!categories.contains(x)) {
           categories.add(x);
@@ -77,10 +88,21 @@ public class AxisTickBarChartCalculator extends AxisTickCalculator {
       }
     }
 
-    int numCategories = categories.size();
+    if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.String) {
+
+      double gridStep = (tickSpace / (double) categories.size());
+      double firstPosition = gridStep / 2.0;
+      int counter = 0;
+      for (Object category : categories) {
+        tickLabels.add(category.toString());
+        double tickLabelPosition = margin + firstPosition + gridStep * counter++;
+        tickLocations.add(tickLabelPosition);
+      }
+    }
+    else if (categories.size() < 13) { // Number or Date and 12 or less categories. give each category a tick label
 
-    int gridStep = (int) (tickSpace / (double) numCategories);
-    int firstPosition = (int) (gridStep / 2.0);
+      double gridStep = (tickSpace / (double) categories.size());
+      double firstPosition = gridStep / 2.0;
 
       // generate all tickLabels and tickLocations from the first to last position
       NumberFormatter numberFormatter = null;
@@ -93,6 +115,7 @@ public class AxisTickBarChartCalculator extends AxisTickCalculator {
         dateFormatter = new DateFormatter(chartPainter.getStyleManager());
       }
       int counter = 0;
+
       for (Object category : categories) {
         if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.Number) {
           tickLabels.add(numberFormatter.formatNumber((Double) category));
@@ -103,11 +126,41 @@ public class AxisTickBarChartCalculator extends AxisTickCalculator {
           long timeUnit = dateFormatter.getTimeUnit(gridStepHint);
           tickLabels.add(dateFormatter.formatDate((Double) category, timeUnit));
         }
-      else if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.String) {
-        tickLabels.add(category.toString());
+        double tickLabelPosition = (int) (margin + firstPosition + gridStep * counter++);
+        tickLocations.add(tickLabelPosition);
       }
-      int tickLabelPosition = margin + firstPosition + gridStep * counter++;
+    }
+    else { // Number or Date and more than 12 categories. divide up the axis tick space according to normal number axis layout
+
+      double gridStep = getNumericalGridStep(tickSpace);
+      double firstPosition = getFirstPosition(gridStep);
+
+      // generate all tickLabels and tickLocations from the first to last position
+      NumberFormatter numberFormatter = null;
+      DateFormatter dateFormatter = null;
+
+      if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.Number) {
+        numberFormatter = new NumberFormatter(styleManager);
+      }
+      else if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.Date) {
+        dateFormatter = new DateFormatter(chartPainter.getStyleManager());
+      }
+
+      for (double tickPosition = firstPosition; tickPosition <= maxValue; tickPosition = tickPosition + gridStep) {
+
+        if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.Number) {
+          tickLabels.add(numberFormatter.formatNumber(tickPosition));
+        }
+        else if (chartPainter.getAxisPair().getXAxis().getAxisType() == AxisType.Date) {
+          long span = (long) Math.abs(maxValue - minValue); // in data space
+          long gridStepHint = (long) (span / (double) tickSpace * styleManager.getXAxisTickMarkSpacingHint());
+          long timeUnit = dateFormatter.getTimeUnit(gridStepHint);
+          tickLabels.add(dateFormatter.formatDate(tickPosition, timeUnit));
+        }
+        double tickLabelPosition = margin + ((tickPosition - minValue) / (maxValue - minValue) * tickSpace);
         tickLocations.add(tickLabelPosition);
       }
     }
+
+  }
 }

xchart/src/main/java/com/xeiam/xchart/internal/chartpart/AxisTickCalculator.java

@@ -29,7 +29,7 @@ import com.xeiam.xchart.internal.chartpart.Axis.Direction;
 public abstract class AxisTickCalculator {
 
   /** the List of tick label position in pixels */
-  protected List<Integer> tickLocations = new LinkedList<Integer>();;
+  protected List<Double> tickLocations = new LinkedList<Double>();;
 
   /** the List of tick label values */
   protected List<String> tickLabels = new LinkedList<String>();
@@ -110,7 +110,7 @@ public abstract class AxisTickCalculator {
     return firstPosition;
   }
 
-  public List<Integer> getTickLocations() {
+  public List<Double> getTickLocations() {
 
     return tickLocations;
   }
@@ -120,4 +120,70 @@ public abstract class AxisTickCalculator {
     return tickLabels;
   }
 
+  /**
+   * Determine the grid step for the data set given the space in pixels allocated for the axis
+   * 
+   * @param tickSpace in plot space
+   * @return
+   */
+  public double getNumericalGridStep(double tickSpace) {
+
+    // this prevents an infinite loop when the plot gets sized really small.
+    if (tickSpace < 10) {
+      return 1.0;
+    }
+
+    // the span of the data
+    double span = Math.abs(maxValue - minValue); // in data space
+
+    int tickMarkSpaceHint = (axisDirection == Direction.X ? styleManager.getXAxisTickMarkSpacingHint() : styleManager.getYAxisTickMarkSpacingHint());
+
+    // for very short plots, squeeze some more ticks in than normal
+    if (axisDirection == Direction.Y && tickSpace < 160) {
+      tickMarkSpaceHint = 25;
+    }
+
+    double gridStepHint = span / tickSpace * tickMarkSpaceHint;
+
+    // gridStepHint --> significand * 10 ** exponent
+    // e.g. 724.1 --> 7.241 * 10 ** 2
+    double significand = gridStepHint;
+    int exponent = 0;
+    if (significand == 0) {
+      exponent = 1;
+    }
+    else if (significand < 1) {
+      while (significand < 1) {
+        significand *= 10.0;
+        exponent--;
+      }
+    }
+    else {
+      while (significand >= 10 || significand == Double.NEGATIVE_INFINITY) {
+        significand /= 10.0;
+        exponent++;
+      }
+    }
+
+    // calculate the grid step with hint.
+    double gridStep;
+    if (significand > 7.5) {
+      // gridStep = 10.0 * 10 ** exponent
+      gridStep = 10.0 * Utils.pow(10, exponent);
+    }
+    else if (significand > 3.5) {
+      // gridStep = 5.0 * 10 ** exponent
+      gridStep = 5.0 * Utils.pow(10, exponent);
+    }
+    else if (significand > 1.5) {
+      // gridStep = 2.0 * 10 ** exponent
+      gridStep = 2.0 * Utils.pow(10, exponent);
+    }
+    else {
+      // gridStep = 1.0 * 10 ** exponent
+      gridStep = Utils.pow(10, exponent);
+    }
+    return gridStep;
+  }
+
 }

xchart/src/main/java/com/xeiam/xchart/internal/chartpart/AxisTickDateCalculator.java

@@ -50,7 +50,7 @@ public class AxisTickDateCalculator extends AxisTickCalculator {
     int tickSpace = (int) (styleManager.getAxisTickSpaceRatio() * workingSpace); // in plot space
 
     // where the tick should begin in the working space in pixels
-    int margin = Utils.getTickStartOffset(workingSpace, tickSpace); // in plot space double gridStep = getGridStepForDecimal(tickSpace);
+    double margin = Utils.getTickStartOffset(workingSpace, tickSpace); // in plot space double gridStep = getGridStepForDecimal(tickSpace);
 
     // the span of the data
     long span = (long) Math.abs(maxValue - minValue); // in data space
@@ -74,7 +74,7 @@ public class AxisTickDateCalculator extends AxisTickCalculator {
 
       tickLabels.add(dateFormatter.formatDate(tickPosition, timeUnit));
       // here we convert tickPosition finally to plot space, i.e. pixels
-      int tickLabelPosition = (int) (margin + ((tickPosition - minValue) / (maxValue - minValue) * tickSpace));
+      double tickLabelPosition = (int) (margin + ((tickPosition - minValue) / (maxValue - minValue) * tickSpace));
       tickLocations.add(tickLabelPosition);
     }
   }