View source for Charts from HTML tables - tutorial

JSXGraph is able to read data from HTML tables and display charts. Here it is explained how to do it.
First, there is an HTML table showing the results of the German Bundestag elections for some parties from 1949 to 2009.
<html>
<table id="mytable" style="border: 1px solid gray;">
<tr>
 <td>Wahljahr</td>
 <td>1949</td>
 <td>1953</td>
 <td>1957</td>
 <td>1961</td>
 <td>1965</td>
 <td>1969</td>
 <td>1972</td>
 <td>1976</td>
 <td>1980</td>
 <td>1983</td>
 <td>1987</td>
 <td>1990</td>
 <td>1994</td>
 <td>1998</td>
 <td>2002</td>
 <td>2005</td>
 <td>2009</td>
</tr>
<tr>
 <td>CDU</td>
 <td>25.2</td>
 <td>36.4</td>
 <td>39.7</td>
 <td>35.8</td>
 <td>39.3</td>
 <td>36.6</td>
 <td>35.2</td> 
 <td>38.0</td>
 <td>34.2</td>
 <td>38.2</td>
 <td>34.5</td>
 <td>36.7</td>
 <td>34.2</td>
 <td>28.4</td>
 <td>29.5</td>
 <td>27.8</td>
 <td>27.3</td> 
</tr>
<tr>
 <td>CSU</td>
 <td>5.8</td>
 <td>8.8</td>
 <td>10.5</td>
 <td>9.6</td>
 <td>9.6</td>
 <td>9.5</td>
 <td>9.7</td> 
 <td>10.6</td>
 <td>10.3</td>
 <td>10.6</td>
 <td>9.8</td>
 <td>7.1</td>
 <td>7.3</td>
 <td>6.7</td>
 <td>9.0</td>
 <td>7.4</td>
 <td>6.5</td> 
</tr>
<tr>
 <td>SPD</td>
 <td>29.2</td>
 <td>28.8</td>
 <td>31.8</td>
 <td>36.2</td>
 <td>39.3</td>
 <td>42.7</td>
 <td>45.8</td> 
 <td>42.6</td>
 <td>42.9</td>
 <td>38.2</td>
 <td>37.0</td>
 <td>33.5</td>
 <td>36.4</td>
 <td>40.9</td>
 <td>38.5</td>
 <td>34.2</td>
 <td>23.0</td>
</tr>
<tr>
 <td>FDP</td>
 <td>11.9</td>
 <td>9.5</td>
 <td>7.7</td>
 <td>12.8</td>
 <td>9.5</td>
 <td>5.8</td>
 <td>8.4</td>
 <td>7.9</td>
 <td>10.6</td>
 <td>7.0</td>
 <td>9.1</td>
 <td>11.0</td>
 <td>6.9</td>
 <td>6.2</td>
 <td>7.4</td>
 <td>9.8</td>
 <td>14.6</td>
</tr>
<tr>
 <td>B&uuml;ndnis 90/Die Gr&uuml;nen</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td> 
 <td>-</td>
 <td>1.5</td>
 <td>5.6</td>
 <td>8.3</td>
 <td>5</td>
 <td>7.3</td>
 <td>6.7</td>
 <td>8.6</td>
 <td>8.1</td>
 <td>10.7</td>
</tr>
</table>
</html>

Then, with some keystrokes the JSXGraph chart from this tables is created.
<jsxgraph width="600" height="450">
        var board1 = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-1, 50, 18, -5], axis: true, grid: false}),
            colors = ['black', '#333333', 'red', 'yellow', 'green', '#8B00FF', 'orange', '#965220', '#96abee', 'gray', '#965220', 'red', 'blue', 'lightgray'],
            years = [1949, 1953, 1957, 1961, 1965, 1969, 1972, 1976, 1980, 1983, 1987, 1990, 1994, 1998, 2002, 2005, 2009],
            hStroke = [], charts1, charts2, charts3, i;

        charts1 = board1.create('chart', ['mytable'], {chartStyle: 'point,line', withHeaders: true, colorArray: colors, strokeColor: colors, fillColor: colors, highlightFillColor: colors, highlightStrokeColor: colors});

        board1.highlightInfobox = function(x,y,el) {
            this.infobox.setText('<span style="color:black;font-weight:bold">' + years[Math.round(x)-1] + ': ' + y + ' %</span>');
            this.infobox.rendNode.style.border = 'groove ' + el.visProp['strokeColor'] + ' 2px';
            this.infobox.rendNode.style.padding = '5px';
            this.infobox.rendNode.style.backgroundColor = 'white';
        }
</jsxgraph>

===The code to produce this page===
The HTML table is generated by this code:
<source lang="html4strict">
<table id="mytable" style="border: 1px solid gray;">
<tr>
 <td>Wahljahr</td>
 <td>1949</td>
 <td>1953</td>
 <td>1957</td>
 <td>1961</td>
 <td>1965</td>
 <td>1969</td>
 <td>1972</td>
 <td>1976</td>
 <td>1980</td>
 <td>1983</td>
 <td>1987</td>
 <td>1990</td>
 <td>1994</td>
 <td>1998</td>
 <td>2002</td>
 <td>2005</td>
 <td>2009</td>
</tr>
<tr>
 <td>CDU</td>
 <td>25.2</td>
 <td>36.4</td>
 <td>39.7</td>
 <td>35.8</td>
 <td>39.3</td>
 <td>36.6</td>
 <td>35.2</td> 
 <td>38.0</td>
 <td>34.2</td>
 <td>38.2</td>
 <td>34.5</td>
 <td>36.7</td>
 <td>34.2</td>
 <td>28.4</td>
 <td>29.5</td>
 <td>27.8</td>
 <td>27.3</td> 
</tr>
<tr>
 <td>CSU</td>
 <td>5.8</td>
 <td>8.8</td>
 <td>10.5</td>
 <td>9.6</td>
 <td>9.6</td>
 <td>9.5</td>
 <td>9.7</td> 
 <td>10.6</td>
 <td>10.3</td>
 <td>10.6</td>
 <td>9.8</td>
 <td>7.1</td>
 <td>7.3</td>
 <td>6.7</td>
 <td>9.0</td>
 <td>7.4</td>
 <td>6.5</td> 
</tr>
<tr>
 <td>SPD</td>
 <td>29.2</td>
 <td>28.8</td>
 <td>31.8</td>
 <td>36.2</td>
 <td>39.3</td>
 <td>42.7</td>
 <td>45.8</td> 
 <td>42.6</td>
 <td>42.9</td>
 <td>38.2</td>
 <td>37.0</td>
 <td>33.5</td>
 <td>36.4</td>
 <td>40.9</td>
 <td>38.5</td>
 <td>34.2</td>
 <td>23.0</td>
</tr>
<tr>
 <td>FDP</td>
 <td>11.9</td>
 <td>9.5</td>
 <td>7.7</td>
 <td>12.8</td>
 <td>9.5</td>
 <td>5.8</td>
 <td>8.4</td>
 <td>7.9</td>
 <td>10.6</td>
 <td>7.0</td>
 <td>9.1</td>
 <td>11.0</td>
 <td>6.9</td>
 <td>6.2</td>
 <td>7.4</td>
 <td>9.8</td>
 <td>14.6</td>
</tr>
<tr>
 <td>B&uuml;ndnis 90/Die Gr&uuml;nen</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td>
 <td>-</td> 
 <td>-</td>
 <td>1.5</td>
 <td>5.6</td>
 <td>8.3</td>
 <td>5</td>
 <td>7.3</td>
 <td>6.7</td>
 <td>8.6</td>
 <td>8.1</td>
 <td>10.7</td>
</tr>
</table>
</source>
<source lang="javascript">
        var board1 = JXG.JSXGraph.initBoard('jxgbox1', {boundingbox: [-1, 50, 18, -5], axis: true, grid: false}),
            board2 = JXG.JSXGraph.initBoard('jxgbox2', {boundingbox: [-1, 50, 18, -5], axis: true, grid: false}),
            board3 = JXG.JSXGraph.initBoard('jxgbox3', {boundingbox: [-1, 50, 18, -5], axis: true, grid: false}),
            colors = ['black', '#333333', 'red', 'yellow', 'green', '#8B00FF', 'orange', '#965220', '#96abee', 'gray', '#965220', 'red', 'blue', 'lightgray'],
            years = [1949, 1953, 1957, 1961, 1965, 1969, 1972, 1976, 1980, 1983, 1987, 1990, 1994, 1998, 2002, 2005, 2009],
            hStroke = [], charts1, charts2, charts3, i;

        //--------------------------------------
        // sub page 1
        //--------------------------------------
        charts1 = board1.create('chart', ['btw'], {chartStyle: 'point,line', withHeaders: true, colorArray: colors, strokeColor: colors, fillColor: colors, highlightFillColor: colors, highlightStrokeColor: colors});

        board1.highlightInfobox = function(x,y,el) {
            this.infobox.setText('<span style="color:black;font-weight:bold">' + years[Math.round(x)-1] + ': ' + y + ' %</span>');
            this.infobox.rendNode.style.border = 'groove ' + el.visProp['strokeColor'] + ' 2px';
            this.infobox.rendNode.style.padding = '5px';
            this.infobox.rendNode.style.backgroundColor = 'white';
        }

        //--------------------------------------
        // sub page 2
        //--------------------------------------
        function select_parties() {
            var i, chartType = 'line', color = [], part;

            if(charts2)
                board2.removeObject(charts2);

            part = [];
            $('input[name=parties]').each(function () { if(this.checked) { part.push(parseInt($(this).val())); color.push(colors[parseInt($(this).val())]); } });

            //if(part.length <4) chartType = 'bar';

	    charts2 = board2.create('chart', ['btw'], {chartStyle: 'point,' + chartType, withHeaders: true, colorArray: color, strokeColor: color, fillColor: color, highlightFillColor: color, highlightStrokeColor: color, rows: part});
        }

        board2.highlightInfobox = function(x,y,el) {
            this.infobox.setText('<span style="color:black;font-weight:bold">' + years[Math.round(x)-1] + ': ' + y + ' %</span>');
            this.infobox.rendNode.style.border = 'groove ' + el.visProp['strokeColor'] + ' 2px';
            this.infobox.rendNode.style.padding = '5px';
            this.infobox.rendNode.style.backgroundColor = 'white';
        }

        //--------------------------------------
        // sub page 3
        //--------------------------------------
        function select_years() {
            var years = [1949, 1953, 1957, 1961, 1965, 1969, 1972, 1976, 1980, 1983, 1987, 1990, 1994, 1998, 2002, 2005],
                i, data, table, col;

            year = parseInt($('#select_years').val());

            table = (new JXG.DataSource()).loadFromTable('btw', true, true);
            col = table.getColumn(year);
            for(i=0; i<col.length; i++) {
                if(isNaN(col[i]))
                    col[i] = 0.;
            }

            if(charts3) {
                for(i=0; i<charts3[0].length; i++) {
                    charts3[0][i].vertices[1].moveTo([charts3[0][i].vertices[1].X(), col[i]], 500);
                    charts3[0][i].vertices[2].moveTo([charts3[0][i].vertices[2].X(), col[i]], 500);
                }
            } else {
                board3.suspendUpdate();
    	    	charts3 = board3.create('chart', [col], {chartStyle: 'bar', colorArray: colors});
                board3.unsuspendUpdate();
            }
        }

        //--------------------------------------
        // general
        //--------------------------------------
        function show(page) {
            var i;
            for(i=0; i<4; i++) {
                $('#page' + i).css('display', 'none');
            }

            $('#' + page).css('display', 'block');
        }
        show('page0');
</source>

[[Category:Examples]]
[[Category:Charts]]