Vue ChartsHistogram Series

Histograms show the frequency distribution of continuous data. They are a good choice for when the data is larger than could be plotted on a bar chart and can be used to find underlying trends in data.

Simple Histogram

Histograms require at least one numeric attribute in the data to be specified using the xKey property. Data will be distributed into bins according to the xKey values.

The simplest configuration for a Histogram Series is shown below:

series: [{
    type: 'histogram'
    xKey: 'age'
}]

Bin Count

By default the histogram will split the X domain of the data into around ten regular-width bins, although the exact number of bins generated will vary so that the chart can find round values for the bin boundaries.

The number of bins to aim for can be overridden by setting the binCount property on a histogram series.

Given enough data, charts with more bins are able to more precisely illustrate underlying trends, but are also more sensitive to random noise.

series: [{
    type: 'histogram'
    xKey: 'age',
    binCount: 20
}]

Irregular Intervals

Rather than specifying the number of bins, for cases where you know exactly which bins you wish to split your X axis values into, it is possible to explicitly give the start and end values for each bin.

This is given using the bins property, and the value should be an array of arrays where each inner array contains the start and end value of a bin.

For histogram charts with irregular bins, it is usual for the area of the bar, rather than its height, to visually represent the value of each bin. In this way the shape of the underlying curve is maintained over irregular intervals. The areaPlot property should be set to true to enable this mode.

In the example below, the data from the race is split into irregular age categories and the areaPlot property has been set to true.

series: [{
    type: 'histogram'
    xKey: 'age',
    areaPlot: true,
    bins: [[16, 18], [18, 21], [21, 25], [25, 40]]
}]

Note that if you give the bins property you should not also give binCount, but if both are present binCount takes precedence.

XY Histogram

The histograms shown above all contain a single xKey with its frequency plotted on the Y axis. However, it is also possible to provide Y values corresponding to the X values, by specifying both xKey and yKey properties.

When using XY Histograms it is useful to control how bins are aggregated using the aggregation series property. The following sections compare the sum and mean aggregation functions.

Summing Bins

The sum aggregation function is used to sum the values of a column or attribute for each of the bins.

When a yKey is specified, the default behaviour is to plot a total of the yKey values. The kind of aggregation to use is controlled by the series.aggregation property.

series: [{
    type: 'histogram'
    xKey: 'age',
    yKey: 'winnings',
    aggregation: 'sum'
}]

Mean Bins

Showing frequencies or summing up the Y values isn't always the best way to visualize your data.

For data that is not evenly distributed in X, but is relatively uniform in Y, a sum plot XY histogram will tend to be dominated by the populations of the X bins.

In the above example you may notice that the prize money distribution very closely follows the age distribution. In such cases, plotting the mean of a bin on the Y axis better illustrates an underlying trend in the data:

series: [{
    type: 'histogram'
    xKey: 'age',
    yKey: 'time',
    yName: 'Race time',
    aggregation: 'mean'
}]

API Reference

Properties available on the AgHistogramSeriesOptions<DatumType = any> interface.

xKey * Typestring	The key to use to retrieve x-values from the data.
type Type'histogram'	'histogram'
fill TypeCssColor Default#f3622d	The colour of the fill for the histogram bars.
stroke TypeCssColor Default#aa4520	The colour of the stroke for the histogram bars.
fillOpacity TypeOpacity Default1	The opacity of the fill for the histogram bars.
strokeOpacity TypeOpacity Default1	The opacity of the stroke for the histogram bars.
strokeWidth TypePixelSize Default1	The width in pixels of the stroke for the histogram bars.
lineDash TypePixelSize[]	Defines how the column strokes are rendered. Every number in the array specifies the length in pixels of alternating dashes and gaps. For example, `[6, 3]` means dashes with a length of `6` pixels with gaps between of `3` pixels.
lineDashOffset TypePixelSize	The initial offset of the dashed line in pixels.
xName Typestring	A human-readable description of the x-values. If supplied, this will be shown in the default tooltip and passed to the tooltip renderer as one of the parameters.
yKey Typestring	The key to use to retrieve y-values from the data.
yName Typestring	A human-readable description of the y-values. If supplied, this will be shown in the default tooltip and passed to the tooltip renderer as one of the parameters.
areaPlot Typeboolean	For variable width bins, if true the histogram will represent the aggregated `yKey` values using the area of the bar. Otherwise, the height of the var represents the value as per a normal bar chart. This is useful for keeping an undistorted curve displayed when using variable-width bins.
bins Type[number, number][]	Set the bins explicitly. The bins need not be of equal width. Note that `bins` is ignored if `binCount` is also supplied.
binCount Typenumber Default10	The number of bins to try to split the x axis into. Clashes with the `bins` setting.
aggregation Type'count' \| 'sum' \| 'mean' Defaultsum	Dictates how the bins are aggregated. If set to 'sum', the value shown for the bins will be the total of the yKey values. If set to 'mean', it will display the average yKey value of the bin. Options: `'count'`, `'sum'`, `'mean'`
shadow TypeAgDropShadowOptions	Configuration for the shadow used behind the chart series.
label TypeAgHistogramSeriesLabelOptions	Configuration for the labels shown on bars.
tooltip TypeAgHistogramSeriesTooltip	Series-specific tooltip configuration.
listeners TypeAgSeriesListeners<DatumType>	A map of event names to event listeners.
id Typestring	Primary identifier for the series. This is provided as `seriesId` in user callbacks to differentiate multiple series. Auto-generated ids are subject to future change without warning, if your callbacks need to vary behaviour by series please supply your own unique `id` value. Default: auto-generated value
data TypeDatumType[]	The data to use when rendering the series. If this is not supplied, data must be set on the chart instead.
visible Typeboolean	Whether or not to display the series.
showInLegend Typeboolean	Whether or not to include the series in the legend.
cursor Typestring	The cursor to use for hovered area markers. This config is identical to the CSS `cursor` property.
highlightStyle TypeAgSeriesHighlightStyle	Configuration for series markers and series line highlighting when a marker / data point or a legend item is hovered over.
nodeClickRange TypeAgChartInteractionRange	Range from a node a click triggers the listener.

Simple Histogram

Bin Count

Irregular Intervals

XY Histogram

Summing Bins

Mean Bins

API Reference

xKey *

type

fill

stroke

fillOpacity

strokeOpacity

strokeWidth

lineDash

lineDashOffset

xName

yKey

yName

areaPlot

bins

binCount

aggregation

shadow

label

tooltip

listeners

id

data

visible

showInLegend

cursor

highlightStyle

nodeClickRange