Bar

A bar chart provides a way of showing data values represented as vertical bars. It is sometimes used to show trend data, and the comparison of multiple data sets side by side.

Example Usage

var myBarChart = new Chart(ctx, {
    type: 'bar',
    data: data,
    options: options
});

Dataset Properties

The bar chart allows a number of properties to be specified for each dataset. These are used to set display properties for a specific dataset. For example, the color of the bars is generally set this way.

General

Styling

The style of each bar can be controlled with the following properties:

All these values, if undefined, fallback to the associated elements.rectangle.* options.

borderSkipped

This setting is used to avoid drawing the bar stroke at the base of the fill. In general, this does not need to be changed except when creating chart types that derive from a bar chart.

Note: for negative bars in vertical chart, top and bottom are flipped. Same goes for left and right in horizontal chart.

Options are:

• 'bottom'
• 'left'
• 'top'
• 'right'
• false

borderWidth

If this value is a number, it is applied to all sides of the rectangle (left, top, right, bottom), except borderSkipped. If this value is an object, the left property defines the left border width. Similarly the right, top and bottom properties can also be specified. Omitted borders and borderSkipped are skipped.

Interactions

The interaction with each bar can be controlled with the following properties:

All these values, if undefined, fallback to the associated elements.rectangle.* options.

Dataset Configuration

The bar chart accepts the following configuration from the associated dataset options:

Example Usage

data: {
    datasets: [{
        barPercentage: 0.5,
        barThickness: 6,
        maxBarThickness: 8,
        minBarLength: 2,
        data: [10, 20, 30, 40, 50, 60, 70]
    }]
};

barThickness

If this value is a number, it is applied to the width of each bar, in pixels. When this is enforced, barPercentage and categoryPercentage are ignored.

If set to 'flex', the base sample widths are calculated automatically based on the previous and following samples so that they take the full available widths without overlap. Then, bars are sized using barPercentage and categoryPercentage. There is no gap when the percentage options are 1. This mode generates bars with different widths when data are not evenly spaced.

If not set (default), the base sample widths are calculated using the smallest interval that prevents bar overlapping, and bars are sized using barPercentage and categoryPercentage. This mode always generates bars equally sized.

Scale Configuration

The bar chart sets unique default values for the following configuration from the associated scale options:

Example Usage

options = {
    scales: {
        xAxes: [{
            gridLines: {
                offsetGridLines: true
            }
        }]
    }
};

offsetGridLines

If true, the bars for a particular data point fall between the grid lines. The grid line will move to the left by one half of the tick interval, which is the space between the grid lines. If false, the grid line will go right down the middle of the bars. This is set to true for a category scale in a bar chart while false for other scales or chart types by default.

Default Options

It is common to want to apply a configuration setting to all created bar charts. The global bar chart settings are stored in Chart.defaults.bar. Changing the global options only affects charts created after the change. Existing charts are not changed.

barPercentage vs categoryPercentage

The following shows the relationship between the bar percentage option and the category percentage option.

// categoryPercentage: 1.0
// barPercentage: 1.0
Bar:        | 1.0 | 1.0 |
Category:   |    1.0    |
Sample:     |===========|
// categoryPercentage: 1.0
// barPercentage: 0.5
Bar:          |.5|  |.5|
Category:  |      1.0     |
Sample:    |==============|
// categoryPercentage: 0.5
// barPercentage: 1.0
Bar:            |1.||1.|
Category:       |  .5  |
Sample:     |==============|

Data Structure

The data property of a dataset for a bar chart is specified as an array of numbers. Each point in the data array corresponds to the label at the same index on the x axis.

data: [20, 10]

You can also specify the dataset as x/y coordinates when using the time scale.

data: [{x:'2016-12-25', y:20}, {x:'2016-12-26', y:10}]

You can also specify the dataset for a bar chart as arrays of two numbers. This will force rendering of bars with gaps between them (floating-bars). First and second numbers in array will correspond the start and the end point of a bar respectively.

data: [[5,6], [-3,-6]]

Stacked Bar Chart

Bar charts can be configured into stacked bar charts by changing the settings on the X and Y axes to enable stacking. Stacked bar charts can be used to show how one data series is made up of a number of smaller pieces.

var stackedBar = new Chart(ctx, {
    type: 'bar',
    data: data,
    options: {
        scales: {
            xAxes: [{
                stacked: true
            }],
            yAxes: [{
                stacked: true
            }]
        }
    }
});

The following dataset properties are specific to stacked bar charts.

Horizontal Bar Chart

A horizontal bar chart is a variation on a vertical bar chart. It is sometimes used to show trend data, and the comparison of multiple data sets side by side.

Example

var myBarChart = new Chart(ctx, {
    type: 'horizontalBar',
    data: data,
    options: options
});

Config Options

The configuration options for the horizontal bar chart are the same as for the bar chart. However, any options specified on the x axis in a bar chart, are applied to the y axis in a horizontal bar chart.

The default horizontal bar configuration is specified in Chart.defaults.horizontalBar.