Blazor Pie Chart

A Blazor Bootstrap pie chart component is a circular chart that shows the proportional values of different categories.

Prerequisites #

Refer to the getting started guide for setting up charts.

How it works #

In the following example, a categorical 12-color palette is used.

TIP

For data visualization, you can use the predefined palettes ColorUtility.CategoricalTwelveColors for a 12-color palette and ColorUtility.CategoricalSixColors for a 6-color palette. These palettes offer a range of distinct and visually appealing colors that can be applied to represent different categories or data elements in your visualizations.

<PieChart @ref="pieChart" Width="500" />

<div class="mt-5">
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="async () => await RandomizeAsync()"> Randomize </Button>
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="async () => await AddDatasetAsync()"> Add Dataset </Button>
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="async () => await AddDataAsync()">Add Data</Button>
</div>

@code {
    private PieChart pieChart = default!;
    private PieChartOptions pieChartOptions = default!;
    private ChartData chartData = default!;
    private string[]? backgroundColors;

    private int datasetsCount = 0;
    private int dataLabelsCount = 0;

    private Random random = new();

    protected override void OnInitialized()
    {
        backgroundColors = ColorUtility.CategoricalTwelveColors;
        chartData = new ChartData { Labels = GetDefaultDataLabels(4), Datasets = GetDefaultDataSets(1) };

        pieChartOptions = new();
        pieChartOptions.Responsive = true;
        pieChartOptions.Plugins.Title!.Text = "2022 - Sales";
        pieChartOptions.Plugins.Title.Display = true;
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            await pieChart.InitializeAsync(chartData, pieChartOptions);
        }
        await base.OnAfterRenderAsync(firstRender);
    }

    private async Task RandomizeAsync()
    {
        if (chartData is null || chartData.Datasets is null || !chartData.Datasets.Any()) return;

        var newDatasets = new List<IChartDataset>();

        foreach (var dataset in chartData.Datasets)
        {
            if (dataset is PieChartDataset pieChartDataset
                && pieChartDataset is not null
                && pieChartDataset.Data is not null)
            {
                var count = pieChartDataset.Data.Count;

                var newData = new List<double?>();
                for (var i = 0; i < count; i++)
                {
                    newData.Add(random.Next(0, 100));
                }

                pieChartDataset.Data = newData;
                newDatasets.Add(pieChartDataset);
            }
        }

        chartData.Datasets = newDatasets;

        await pieChart.UpdateAsync(chartData, pieChartOptions);
    }

    private async Task AddDatasetAsync()
    {
        if (chartData is null || chartData.Datasets is null) return;

        var chartDataset = GetRandomPieChartDataset();
        chartData = await pieChart.AddDatasetAsync(chartData, chartDataset, pieChartOptions);
    }

    private async Task AddDataAsync()
    {
        if (dataLabelsCount >= 12)
            return;

        if (chartData is null || chartData.Datasets is null)
            return;

        var data = new List<IChartDatasetData>();
        foreach (var dataset in chartData.Datasets)
        {
            if (dataset is PieChartDataset pieChartDataset)
                data.Add(new PieChartDatasetData(pieChartDataset.Label, random.Next(0, 100), backgroundColors![dataLabelsCount]));
        }

        chartData = await pieChart.AddDataAsync(chartData, GetNextDataLabel(), data);

        dataLabelsCount += 1;
    }

    #region Data Preparation

    private List<IChartDataset> GetDefaultDataSets(int numberOfDatasets)
    {
        var datasets = new List<IChartDataset>();

        for (var index = 0; index < numberOfDatasets; index++)
        {
            datasets.Add(GetRandomPieChartDataset());
        }

        return datasets;
    }

    private PieChartDataset GetRandomPieChartDataset()
    {
        datasetsCount += 1;
        return new() { Label = $"Team {datasetsCount}", Data = GetRandomData(), BackgroundColor = GetRandomBackgroundColors() };
    }

    private List<double?> GetRandomData()
    {
        var data = new List<double?>();
        for (var index = 0; index < dataLabelsCount; index++)
        {
            data.Add(random.Next(0, 100));
        }

        return data;
    }

    private List<string> GetRandomBackgroundColors()
    {
        var colors = new List<string>();
        for (var index = 0; index < dataLabelsCount; index++)
        {
            colors.Add(backgroundColors![index]);
        }

        return colors;
    }

    private List<string> GetDefaultDataLabels(int numberOfLabels)
    {
        var labels = new List<string>();
        for (var index = 0; index < numberOfLabels; index++)
        {
            labels.Add(GetNextDataLabel());
            dataLabelsCount += 1;
        }

        return labels;
    }

    private string GetNextDataLabel() => $"Product {dataLabelsCount + 1}";

    private string GetNextDataBackgrounfColor() => backgroundColors![dataLabelsCount];

    #endregion  Data Preparation
}

Data labels #

<PieChart @ref="pieChart" Width="500" />

<div class="mt-5">
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="async () => await RandomizeAsync()"> Randomize </Button>
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="async () => await AddDataAsync()">Add Data</Button>
</div>

@code {
    private PieChart pieChart = default!;
    private PieChartOptions pieChartOptions = default!;
    private ChartData chartData = default!;
    private string[]? backgroundColors;

    private int datasetsCount = 0;
    private int dataLabelsCount = 0;

    private Random random = new();

    protected override void OnInitialized()
    {
        backgroundColors = ColorUtility.CategoricalTwelveColors;
        chartData = new ChartData { Labels = GetDefaultDataLabels(4), Datasets = GetDefaultDataSets(3) };

        pieChartOptions = new();
        pieChartOptions.Responsive = true;
        pieChartOptions.Plugins.Title!.Text = "2022 - Sales";
        pieChartOptions.Plugins.Title.Display = true;
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            // pass the plugin name to enable the data labels
            await pieChart.InitializeAsync(chartData: chartData, chartOptions: pieChartOptions, plugins: new string[] { "ChartDataLabels" });
        }
        await base.OnAfterRenderAsync(firstRender);
    }

    private async Task RandomizeAsync()
    {
        if (chartData is null || chartData.Datasets is null || !chartData.Datasets.Any()) return;

        var newDatasets = new List<IChartDataset>();

        foreach (var dataset in chartData.Datasets)
        {
            if (dataset is PieChartDataset pieChartDataset
                && pieChartDataset is not null
                && pieChartDataset.Data is not null)
            {
                var count = pieChartDataset.Data.Count;

                var newData = new List<double?>();
                for (var i = 0; i < count; i++)
                {
                    newData.Add(random.Next(0, 100));
                }

                pieChartDataset.Data = newData;
                newDatasets.Add(pieChartDataset);
            }
        }

        chartData.Datasets = newDatasets;

        await pieChart.UpdateAsync(chartData, pieChartOptions);
    }

    private async Task AddDataAsync()
    {
        if (dataLabelsCount >= 12)
            return;

        if (chartData is null || chartData.Datasets is null)
            return;

        var data = new List<IChartDatasetData>();
        foreach (var dataset in chartData.Datasets)
        {
            if (dataset is PieChartDataset pieChartDataset)
                data.Add(new PieChartDatasetData(pieChartDataset.Label, random.Next(0, 100), backgroundColors![dataLabelsCount]));
        }

        chartData = await pieChart.AddDataAsync(chartData, GetNextDataLabel(), data);

        dataLabelsCount += 1;
    }

    #region Data Preparation

    private List<IChartDataset> GetDefaultDataSets(int numberOfDatasets)
    {
        var datasets = new List<IChartDataset>();

        for (var index = 0; index < numberOfDatasets; index++)
        {
            var dataset = GetRandomPieChartDataset();

            if (index == 0)
                dataset.Datalabels.Anchor = Anchor.End;
            else if (index == numberOfDatasets - 1)
                dataset.Datalabels.Anchor = Anchor.End;
            else
                dataset.Datalabels.Anchor = Anchor.Center;

            datasets.Add(dataset);
        }

        return datasets;
    }

    private PieChartDataset GetRandomPieChartDataset()
    {
        datasetsCount += 1;
        return new() { Label = $"Team {datasetsCount}", Data = GetRandomData(), BackgroundColor = GetRandomBackgroundColors() };
    }

    private List<double?> GetRandomData()
    {
        var data = new List<double?>();
        for (var index = 0; index < dataLabelsCount; index++)
        {
            data.Add(random.Next(0, 100));
        }

        return data;
    }

    private List<string> GetRandomBackgroundColors()
    {
        var colors = new List<string>();
        for (var index = 0; index < dataLabelsCount; index++)
        {
            colors.Add(backgroundColors![index]);
        }

        return colors;
    }

    private List<string> GetDefaultDataLabels(int numberOfLabels)
    {
        var labels = new List<string>();
        for (var index = 0; index < numberOfLabels; index++)
        {
            labels.Add(GetNextDataLabel());
            dataLabelsCount += 1;
        }

        return labels;
    }

    private string GetNextDataLabel() => $"Product {dataLabelsCount + 1}";

    private string GetNextDataBackgrounfColor() => backgroundColors![dataLabelsCount];

    #endregion  Data Preparation
}

Change legend position #

This sample demonstrates how to change the position of the chart legend.

<PieChart @ref="pieChart" Width="500" />

<div class="mt-5">
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="PositionTopAsync"> Position: top </Button>
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="PositionRightAsync"> Position: right </Button>
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="PositionBottomAsync"> Position: bottom </Button>
    <Button Type="ButtonType.Button" Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="PositionLeftAsync"> Position: left </Button>
</div>

@code {
    private PieChart pieChart = default!;
    private PieChartOptions pieChartOptions = default!;
    private ChartData chartData = default!;
    private string[]? backgroundColors;

    private int datasetsCount = 0;
    private int dataLabelsCount = 0;

    private Random random = new();

    protected override void OnInitialized()
    {
        backgroundColors = ColorUtility.CategoricalTwelveColors;
        chartData = new ChartData { Labels = GetDefaultDataLabels(4), Datasets = GetDefaultDataSets(1) };

        pieChartOptions = new();
        pieChartOptions.Responsive = true;
        pieChartOptions.Plugins.Title!.Text = "2022 - Sales";
        pieChartOptions.Plugins.Title.Display = true;

        pieChartOptions.Plugins.Legend.Position = "right";
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            await pieChart.InitializeAsync(chartData, pieChartOptions);
        }
        await base.OnAfterRenderAsync(firstRender);
    }

    private async Task PositionTopAsync() => await UpdatePositionAsync("top");
    private async Task PositionRightAsync() => await UpdatePositionAsync("right");
    private async Task PositionBottomAsync() => await UpdatePositionAsync("bottom");
    private async Task PositionLeftAsync() => await UpdatePositionAsync("left");

    private async Task UpdatePositionAsync(string position)
    {
        pieChartOptions.Plugins.Legend.Position = position;
        await pieChart.UpdateAsync(chartData, pieChartOptions);
    }

    #region Data Preparation

    private List<IChartDataset> GetDefaultDataSets(int numberOfDatasets)
    {
        var datasets = new List<IChartDataset>();

        for (var index = 0; index < numberOfDatasets; index++)
        {
            datasets.Add(GetRandomPieChartDataset());
        }

        return datasets;
    }

    private PieChartDataset GetRandomPieChartDataset()
    {
        datasetsCount += 1;
        return new() { Label = $"Team {datasetsCount}", Data = GetRandomData(), BackgroundColor = GetRandomBackgroundColors() };
    }

    private List<double?> GetRandomData()
    {
        var data = new List<double?>();
        for (var index = 0; index < dataLabelsCount; index++)
        {
            data.Add(random.Next(0, 100));
        }

        return data;
    }

    private List<string> GetRandomBackgroundColors()
    {
        var colors = new List<string>();
        for (var index = 0; index < dataLabelsCount; index++)
        {
            colors.Add(backgroundColors![index]);
        }

        return colors;
    }

    private List<string> GetDefaultDataLabels(int numberOfLabels)
    {
        var labels = new List<string>();
        for (var index = 0; index < numberOfLabels; index++)
        {
            labels.Add(GetNextDataLabel());
            dataLabelsCount += 1;
        }

        return labels;
    }

    private string GetNextDataLabel() => $"Product {dataLabelsCount + 1}";

    private string GetNextDataBackgrounfColor() => backgroundColors![dataLabelsCount];

    #endregion  Data Preparation
}

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Blazor Pie Chart

Prerequisites #

How it works #

Data labels #

Change legend position #

Links

Guides

Community