I'm trying to draw a Google bar chart with a logarithmic scale. However, it starts at 1, not 0. This looks like bad data because entries with one value are rendered with no bar. I tried settingminValue to zero, but it won't seem to honor that when logScale is true.

Is it even possible to have a logarithmic scale that starts at zero?

Here's some code that reproduces the problem on the visualization playground:

function drawVisualization() {
// Create and populate the data table.
        var data = new google.visualization.DataTable();
        data.addColumn('number', 'Age');
        data.addColumn('number', 'Weight');
        data.addRows(6);
        data.setValue(0, 0, 8);
        data.setValue(0, 1, 12);
        data.setValue(1, 0, 4);
        data.setValue(1, 1, 5.5);
        data.setValue(2, 0, 11);
        data.setValue(2, 1, 14);
        data.setValue(3, 0, 4);
        data.setValue(3, 1, 4.5);
        data.setValue(4, 0, 3);
        data.setValue(4, 1, 3.5);
        data.setValue(5, 0, 6.5);
        data.setValue(5, 1, 7);

  // Create and draw the visualization.
  new google.visualization.BarChart(document.getElementById('visualization')).
      draw(data,
           {title:"Yearly Coffee Consumption by Country",
            width:600, height:400,
            vAxis: {title: "Year"},
            hAxis: {title: "Cups", minValue: 0, logScale: true}}
      );
}

I'm trying to draw a Google bar chart with a logarithmic scale. However, it starts at 1, not 0. This looks like bad data because entries with one value are rendered with no bar. I tried settingminValue to zero, but it won't seem to honor that when logScale is true.

Is it even possible to have a logarithmic scale that starts at zero?

Here's some code that reproduces the problem on the visualization playground:

function drawVisualization() {
// Create and populate the data table.
        var data = new google.visualization.DataTable();
        data.addColumn('number', 'Age');
        data.addColumn('number', 'Weight');
        data.addRows(6);
        data.setValue(0, 0, 8);
        data.setValue(0, 1, 12);
        data.setValue(1, 0, 4);
        data.setValue(1, 1, 5.5);
        data.setValue(2, 0, 11);
        data.setValue(2, 1, 14);
        data.setValue(3, 0, 4);
        data.setValue(3, 1, 4.5);
        data.setValue(4, 0, 3);
        data.setValue(4, 1, 3.5);
        data.setValue(5, 0, 6.5);
        data.setValue(5, 1, 7);

  // Create and draw the visualization.
  new google.visualization.BarChart(document.getElementById('visualization')).
      draw(data,
           {title:"Yearly Coffee Consumption by Country",
            width:600, height:400,
            vAxis: {title: "Year"},
            hAxis: {title: "Cups", minValue: 0, logScale: true}}
      );
}

• javascript
• google-visualization

2 Answers 2

You cannot have 0 (or a negative value) on a logarithmic scale because log(0) = -infinity. You can however set the the minValue to a low value, like 0.1, 0.001, or whatever suits your data.

This is rather old, but came up in a google search, so I'll leave this pointer here...there is an undocumented option "scaleType": "mirrorLog" that supports negative/zero values in a log scale (by switching to linear for small values).

See-also https://code.google./p/google-visualization-api-issues/issues/detail?id=984