~/piechart/pieseries.md

Pie Series

This article do not include all the properties of the Pie Series class, it only highlights some features, to explore the full object checkout the API explorer

Name property

The name property is a string identifier that is normally used in tooltips and legends to display the data name, if this property is not set, then the library will generate a name for the series that by default is called "Series 1" when it is the first series in the series collection, "Series 2" when it is the second series in the series collection, "Series 3" when it is the third series in the series collection, and so on a series n will be named "Series n".

SeriesCollection = new ISeries[]
{
    new PieSeries<int>
    {
        Values = new []{ 2, 5, 4, 2, 6 },
        Name = "Income", // mark
        Stroke = null
    },
    new PieSeries<int>
    {
        Values = new []{ 3, 7, 2, 9, 4 },
        Name = "Outcome", // mark
        Stroke = null
    }
};

Values property

The Values property is of type IEnumerable<T>, this means that you can use any object that implements the IEnumerable<T> interface, such as Array, List<T> or ObservableCollection<T>, this property contains the data to plot, you can use any type as the generic argument (<T>) as soon as you let the library how to handle it, the library already knows how to handle multiple types, but you can register any type and teach the library how to handle any object in a chart, for more information please see the mappers article.

var series1 = new PieSeries<int>
{
    Values = new List<int> { 2, 1, 3 }
};

// == Update the chart when a value is added, removed or replaced  == // mark
// using ObservableCollections allows the chart to update
// every time you add a new element to the values collection
// (not needed in Blazor, it just... updates)
var series2 = new PieSeries<double>
{
    Values = new ObservableCollection<double> { 2, 1, 3 }
}
series2.add(4); // and the chart will animate the change!

// == Update the chart when a property in our collection changes  == // mark
// if the object implements INotifyPropertyChanged, then the chart will
// update automatically when a property changes, the library already provides
// many 'ready to go' objects such as the ObservableValue class.
var observableValue =  new ObservableValue(5);
var series3 = new PieSeries<ObservableValue>
{
    Values = new ObservableCollection<ObservableValue> { observableValue },
}
observableValue.Value = 9; // the chart will animate the change from 5 to 9!

// == Passing X and Y coordinates // mark 
// you can indicate both, X and Y using the Observable point class.
// or you could define your own object using mappers.
var series4 = new PieSeries<ObservablePoint>
{
    Values = new ObservableCollection<ObservablePoint> { new ObservablePoint(2, 6)}
}
// == Custom types and mappers == // mark
// finally you can also use your own object, take a look at the City class.
public class City 
{
    public string Name { get; set; }
    public double Population { get; set; }
}
// we must let the series know how to handle the city class.
// use the Mapping property to build a point from the city class
// you could also register the map globally.
// for more about global mappers info see:
// https://lvcharts.com/docs/unowinui/2.0.0-beta.330/Overview.Mappers
var citiesSeries = new PieSeries<City>
{
    Values = new City[]
    { 
        new City { Name = "Tokio", Population = 9 },
        new City { Name = "New York", Population = 11 },
        new City { Name = "Mexico City", Population = 10 },
    },
    Mapping = (city, point) =>
    {
        // this function will be called for every city in our data collection
        // in this case Tokio, New York and Mexico city
        // it takes the city and the point in the chart liveCharts built for the given city
        // you must map the coordinates to the point

        // use the Population property as the primary value (normally Y)
        point.PrimaryValue = (float)city.Population;

        // use the index of the city in our data collection as the secondary value
        // (normally X)
        point.SecondaryValue = point.Context.Index;
    }
};

Automatic updates do not have a significant performance impact in most of the cases!

DataLabels

Data labels are labels for every point in a series, there are multiple properties to customize them, take a look at the following sample:

Series { get; set; } = new List<ISeries>
{
    new PieSeries<double>
    {
        Values = new List<double> { 8 },
        DataLabelsPaint = new SolidColorPaint(SKColors.Black),
        DataLabelsSize = 22,
        // for more information about available positions see:
        // https://lvcharts.com/api/2.0.0-beta.330/LiveChartsCore.Measure.PolarLabelsPosition
        DataLabelsPosition = LiveChartsCore.Measure.PolarLabelsPosition.Middle,
        DataLabelsFormatter = point => point.PrimaryValue.ToString("N2") + " elements"
    },
    new PieSeries<double>
    {
        Values = new List<double> { 6 },
        DataLabelsPaint = new SolidColorPaint(SKColors.Black),
        DataLabelsSize = 22,
        DataLabelsPosition = LiveChartsCore.Measure.PolarLabelsPosition.Middle,
        DataLabelsFormatter = point => point.PrimaryValue.ToString("N2") + " elements"
    },
    new PieSeries<double>
    {
        Values = new List<double> { 4 },
        DataLabelsPaint = new SolidColorPaint(SKColors.Black),
        DataLabelsSize = 22,
        DataLabelsPosition = LiveChartsCore.Measure.PolarLabelsPosition.Middle,
        DataLabelsFormatter = point => point.PrimaryValue.ToString("N2") + " elements"
    }
};

The series above result in the following chart:

image

You can also use the DataLabelsRotation property to set an angle in degrees for the labels in the chart, notice the constants LiveCharts.CotangentAngle and LiveCharts.TangentAngle to build labels rotation.

This is the result when we set all the series to LiveCharts.CotangentAngle:

image

And this is the result when we set all the series to LiveCharts.TangentAngle:

image

Finally you can also combine tangent and cotangent angles with decimal degrees:

Series { get; set; } = new List<ISeries>
{
    new PieSeries<double>
    {
        DataLabelsRotation = 30, // in degrees
    },
    new PieSeries<double>
    {
        DataLabelsRotation = LiveCharts.TangentAngle + 30, // the tangent + 30 degrees
    },
    new PieSeries<double>
    {
        DataLabelsRotation = LiveCharts.CotangentAngle + 30, // the cotangent + 30 degrees
    }
};

Stroke property

If the stroke property is not set, then LiveCharts will create it based on the series position in your series collection and the current theme.

image

Paints can create gradients, dashed lines and more, if you need help using the Paint instances take a look at the Paints article.

Fill property

If the fill property is not set, then LiveCharts will create it based on the series position in your series collection and the current theme.

image

Paints can create gradients, dashed lines and more, if you need help using the Paint instances take a look at the Paints article.

Pushout property

It is the distance in pixels between the center of the control and the pie slice, notice the HoverPushout property defines the push-out when the pointer is above the pie slice shape.

var pieSeries = new PieSeries<int>
{
    Values = new [] { ... },
    Pushout = 40 // mark
};

image

InnerRadius property

The inner radius of the slice in pixels.

var pieSeries = new PieSeries<int>
{
    Values = new [] { ... },
    InnerRadius = 50 // mark 
};

image

MaxOuterRadius property

Specifies the max radius (in percentage) the slice can take, the value goes from 0 to 1, where 1 is the full available radius and 0 is none, default is 1.

var pieSeries = new PieSeries<int>
{
    Values = new [] { ... },
    MaxOuterRadius = 0.8 // mark
};

image

ZIndex property

Indicates an order in the Z axis, this order controls which series is above or behind.

IsVisible property

Indicates if the series is visible in the user interface.

DataPadding

The data padding is the minimum distance from the edges of the series to the axis limits, it is of type System.Drawing.PointF both coordinates (X and Y) goes from 0 to 1, where 0 is nothing and 1 is the axis tick an axis tick is the separation between every label or separator (even if they are not visible).

If this property is not set, the library will set it according to the series type, take a look at the following samples:

new LineSeries<double>
{
    DataPadding = new System.Drawing.PointF(0, 0),
    Values = new ObservableCollection { 2, 1, 3, 5, 3, 4, 6 },
    GeometryStroke = null,
    GeometryFill = null,
    Fill = null
}

Produces the following result:

image

But you can remove the padding only from an axis, for example:

new LineSeries<double>
{
    DataPadding = new System.Drawing.PointF(0.5f, 0),
    Values = new ObservableCollection<double> { 2, 1, 3, 5, 3, 4, 6 },
    GeometryStroke = null,
    GeometryFill = null,
    Fill = null
}

image

Or you can increase the distance:

new LineSeries<double>
{
    DataPadding = new System.Drawing.PointF(2, 2),
    Values = new ObservableCollection<double> { 2, 1, 3, 5, 3, 4, 6 },
    GeometryStroke = null,
    GeometryFill = null,
    Fill = null
}

image