Change Data Range in Excel Line Chart using Apache POI

Question

I am trying to see if it is possible to change the data range of a series in a line chart using Apache POI.

I am able to pull the series from the chart itself, but cannot find a method that allows me to change the data range.

XSSFWorkbook workbook = new XSSFWorkbook("C:\\Workbook.xlsx");
Sheet worksheet = workbook.getSheetAt(0);
XSSFDrawing drawing = (XSSFDrawing) worksheet.createDrawingPatriarch();
List<XSSFChart> charts = drawing.getCharts();
for (XSSFChart chart : charts) {
    String title = chart.getTitleText().toString();
    if (title.equals("Z-Acceleration")) {
        CTChart cc = chart.getCTChart();
        CTPlotArea plotArea = cc.getPlotArea();
        CTLineSer[] ccc = plotArea.getLineChartArray()[0].getSerArray();
        for (CTLineSer s : ccc) {
            System.out.println(s.xmlText());
        }
        System.out.println(ccc.length);
    }
}

I printed out the XML text to see if it was indeed able to pull the series from the chart correctly and was able to find its title and data range, but no way to change it.

Answer 1

OK, since this is a good question at all, let's have a concrete example of how to change data range in Excel line chart using apache poi.

Let's start with following sheet:

Then the following code:

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.*;
import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.ss.SpreadsheetVersion;

import org.openxmlformats.schemas.drawingml.x2006.chart.*;

import java.io.FileInputStream;
import java.io.FileOutputStream;

import java.util.List;

class ExcelChangeChartDataSource {

 static XSSFChart getChartWithTitle(XSSFSheet sheet, String wantedTitle) {
  if (sheet == null || wantedTitle == null) return null;
  XSSFDrawing drawing = sheet.createDrawingPatriarch();
  List<XSSFChart> charts = drawing.getCharts();
  for (XSSFChart chart : charts) {
   String title = chart.getTitleText().toString();
   if (wantedTitle.equals(title)) return chart;
  }
  return null;
 }

 static void addMonthDataToChart(XSSFSheet sheet, XSSFChart chart, String month, Double[] seriesData) {
  CTChart ctChart = chart.getCTChart();
  CTPlotArea ctPlotArea = ctChart.getPlotArea();
  List<CTLineSer> ctLineSerList = ctPlotArea.getLineChartArray(0).getSerList();

  Row row;
  Cell cell;
  int ser = 0;
  for (CTLineSer ctLineSer : ctLineSerList) {

   CTAxDataSource cttAxDataSource = ctLineSer.getCat();
   CTStrRef ctStrRef = cttAxDataSource.getStrRef();

   AreaReference catReference = new AreaReference(ctStrRef.getF(), SpreadsheetVersion.EXCEL2007);
   CellReference firstCatCell = catReference.getFirstCell();
   CellReference lastCatCell = catReference.getLastCell();
   if (firstCatCell.getCol() == lastCatCell.getCol()) {
    int col = firstCatCell.getCol();
    int lastRow = lastCatCell.getRow();
    row = sheet.getRow(lastRow+1); if (row == null) row = sheet.createRow(lastRow+1);
    cell = row.getCell(col); if (cell == null) cell = row.createCell(col);
    cell.setCellValue(month);

    ctStrRef.setF(new AreaReference(
                  firstCatCell, 
                  new CellReference(lastCatCell.getSheetName(), lastRow+1, col, true, true), 
                  SpreadsheetVersion.EXCEL2007).formatAsString()
                 );

    CTNumDataSource ctNumDataSource = ctLineSer.getVal();
    CTNumRef ctNumRef = ctNumDataSource.getNumRef();

    AreaReference numReference = new AreaReference(ctNumRef.getF(), SpreadsheetVersion.EXCEL2007);
    CellReference firstNumCell = numReference.getFirstCell();
    CellReference lastNumCell = numReference.getLastCell();
    if (lastNumCell.getRow() == lastRow && firstNumCell.getCol() == lastNumCell.getCol()) {
     col = firstNumCell.getCol();
     row = sheet.getRow(lastRow+1); if (row == null) row = sheet.createRow(lastRow+1);
     cell = row.getCell(col); if (cell == null) cell = row.createCell(col);
     if (ser < seriesData.length) cell.setCellValue(seriesData[ser]);

     ctNumRef.setF(new AreaReference(
                   firstNumCell, 
                   new CellReference(lastNumCell.getSheetName(), lastRow+1, col, true, true), 
                   SpreadsheetVersion.EXCEL2007).formatAsString()
                  );
    }
   }
   ser++;
  }
 }

 public static void main(String[] args) throws Exception {

  XSSFWorkbook workbook = (XSSFWorkbook)WorkbookFactory.create(new FileInputStream("WorkbookWithChart.xlsx"));

  XSSFSheet sheet = workbook.getSheetAt(0);

  XSSFChart chart = getChartWithTitle(sheet, "Z-Acceleration"); 

  if (chart != null) {
   addMonthDataToChart(sheet, chart, "Apr", new Double[]{7d,3d,5d});
   addMonthDataToChart(sheet, chart, "Mai", new Double[]{2d,6d,8d});
   addMonthDataToChart(sheet, chart, "Jun", new Double[]{1d,9d,4d});
   addMonthDataToChart(sheet, chart, "Jul", new Double[]{5d,6d});
  }

  FileOutputStream out = new FileOutputStream("WorkbookWithChartNew.xlsx");
  workbook.write(out);
  out.close();
  workbook.close();
 }
}

produces following result:

This code uses org.openxmlformats.schemas.drawingml.x2006.chart.* classes and can be used with apache poi 3.17 as well as with apache poi 4.1.0.

Unfortunately there is not any API documentation of org.openxmlformats.schemas.drawingml.x2006.chart.* public available. So if we need it, we need to download ooxml-schemas-1.3-sources.jar from central.maven.org/maven2/org/apache/poi/ooxml-schemas/1.3. Then unzip that. Then go to directory ooxml-schemas-1.3 and do javadoc -d javadoc -sourcepath ./ -subpackages org. After that we find the API docs in ooxml-schemas-1.3/javadoc. Start reading with overview-tree.html.

For apache poi 4.1.0 we need ooxml-schemas-1.4.

I have tried the same using the new XDDF stuff in apache poi 4.1.0 too. But at first the code is not really much less expensive and at second this has the disadvantage that XDDFChart.plot fails when some data in XDDFNumericalDataSource<Double> values are not present. Then we would must set those data points 0. But this is not the same as not present. So using the new XDDFstuff in this case is not really a progress. But nevertheless, here is the code, i have tried:

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.*;
import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.ss.SpreadsheetVersion;

import org.apache.poi.xddf.usermodel.chart.*;

import java.io.FileInputStream;
import java.io.FileOutputStream;

import java.util.List;

class ExcelChangeChartDataSource {

 static XSSFChart getChartWithTitle(XSSFSheet sheet, String wantedTitle) {
  if (sheet == null || wantedTitle == null) return null;
  XSSFDrawing drawing = sheet.createDrawingPatriarch();
  List<XSSFChart> charts = drawing.getCharts();
  for (XSSFChart chart : charts) {
   String title = chart.getTitleText().toString();
   if (wantedTitle.equals(title)) return chart;
  }
  return null;
 }

 static void addMonthDataToChart(XSSFSheet sheet, XSSFChart chart, String month, Double[] seriesData) {
  Row row;
  Cell cell;

  List<XDDFChartData> chartDataList = chart.getChartSeries();
  XDDFChartData chartData = chartDataList.get(0);

  List<XDDFChartData.Series> seriesList = chartData.getSeries();
  int ser = 0;
  for (XDDFChartData.Series series : seriesList) {
   XDDFDataSource categoryData = series.getCategoryData();
   AreaReference catReference = new AreaReference(categoryData.getDataRangeReference(), SpreadsheetVersion.EXCEL2007);
   CellReference firstCatCell = catReference.getFirstCell();
   CellReference lastCatCell = catReference.getLastCell();
   if (firstCatCell.getCol() == lastCatCell.getCol()) {
    int col = firstCatCell.getCol();
    int lastRow = lastCatCell.getRow();
    row = sheet.getRow(lastRow+1); if (row == null) row = sheet.createRow(lastRow+1);
    cell = row.getCell(col); if (cell == null) cell = row.createCell(col);
    cell.setCellValue(month);

    XDDFDataSource<String> category = XDDFDataSourcesFactory.fromStringCellRange(
                                       sheet, 
                                       new CellRangeAddress(firstCatCell.getRow(), lastRow+1, col, col));

    XDDFNumericalDataSource valuesData = series.getValuesData();
    AreaReference numReference = new AreaReference(valuesData.getDataRangeReference(), SpreadsheetVersion.EXCEL2007);
    CellReference firstNumCell = numReference.getFirstCell();
    CellReference lastNumCell = numReference.getLastCell();
    if (lastNumCell.getRow() == lastRow && firstNumCell.getCol() == lastNumCell.getCol()) {
     col = firstNumCell.getCol();
     row = sheet.getRow(lastRow+1); if (row == null) row = sheet.createRow(lastRow+1);
     cell = row.getCell(col); if (cell == null) cell = row.createCell(col);
     if (ser < seriesData.length) cell.setCellValue(seriesData[ser]);
     else cell.setCellValue(0); // Here we need set 0 where it not should be needed.

     XDDFNumericalDataSource<Double> values = XDDFDataSourcesFactory.fromNumericCellRange(
                                               sheet, 
                                               new CellRangeAddress(firstNumCell.getRow(), lastRow+1, col, col));

     series.replaceData(category, values);
    }
   }
   ser++;
  }
  chart.plot(chartData);
 }

 public static void main(String[] args) throws Exception {

  XSSFWorkbook workbook = (XSSFWorkbook)WorkbookFactory.create(new FileInputStream("WorkbookWithChart.xlsx"));

  XSSFSheet sheet = workbook.getSheetAt(0);

  XSSFChart chart = getChartWithTitle(sheet, "Z-Acceleration"); 

  if (chart != null) {
   addMonthDataToChart(sheet, chart, "Apr", new Double[]{7d,3d,5d});
   addMonthDataToChart(sheet, chart, "Mai", new Double[]{2d,6d,8d});
   addMonthDataToChart(sheet, chart, "Jun", new Double[]{1d,9d,4d});
   addMonthDataToChart(sheet, chart, "Jul", new Double[]{5d,6d});
  }

  FileOutputStream out = new FileOutputStream("WorkbookWithChartNew.xlsx");
  workbook.write(out);
  out.close();
  workbook.close();

 }
}

Answer 2

Instead of adding new rows, you can remove data from the chart display by setting the row height to zero.

First, create the chart with largest possible data range, like the following.

Then, use the following code to set the rows that you don't want to see in the graph with height zero.

    for(int i=8;i<14;i++) {
        sheet.getRow(i).setZeroHeight(true);;
    }

And now you will see the output Excel changed to the following.

By the way, you can also update the graph title by linking it to a cell value, like the example above, with the graph title linked to cell A1.