SectorMark

Creates circular segments (wedges) based on angular data, suited for pie and donut charts showing proportional relationships and part-to-whole comparisons. Setting inner_radius to a value greater than zero creates a donut chart instead of a pie chart.

The angle field determines the size of each sector proportionally. Use foreground_style with a PlottableField to automatically assign colors to each category.

SectorMark is used inside a Chart container as one of the marks entries.

Constructor¶

nib.SectorMark(
    angle,
    foreground_style=None,
    inner_radius=None,
    outer_radius=None,
    angle_start=None,
    corner_radius=None,
    opacity=None,
)

Parameters¶

Parameter	Type	Default	Description
`angle`	`str \\| PlottableField`	required	Data field containing values that determine sector sizes. Values are treated proportionally -- a sector with value 20 is twice as large as one with value 10.
`foreground_style`	`str \\| PlottableField`	`None`	Fill color for sectors. Use a `PlottableField` with a categorical field to automatically assign different colors to each sector.
`inner_radius`	`float`	`None`	Inner radius in points. Set to `0` (or omit) for a pie chart. Set to a positive value for a donut chart.
`outer_radius`	`float`	`None`	Outer radius in points. Defaults to automatic sizing based on available space.
`angle_start`	`str \\| PlottableField`	`None`	Data field or value for the starting angle of sectors. Rarely needed; use for custom sector positioning.
`corner_radius`	`float`	`None`	Radius for rounded sector corners in points. Creates a softer visual appearance.
`opacity`	`float`	`None`	Opacity from 0.0 to 1.0.

Examples¶

Pie chart¶

import nib

def main(app: nib.App):
    chart = nib.Chart(
        data=[
            {"category": "Electronics", "value": 42},
            {"category": "Clothing", "value": 28},
            {"category": "Food", "value": 20},
            {"category": "Books", "value": 10},
        ],
        marks=[
            nib.SectorMark(
                angle="value",
                foreground_style=nib.PlottableField("category"),
            ),
        ],
        legend=nib.ChartLegend(position="bottom"),
        width=300,
        height=300,
    )
    app.build(chart)

nib.run(main)

Donut chart¶

import nib

chart = nib.Chart(
    data=[
        {"segment": "Used", "percentage": 65},
        {"segment": "Free", "percentage": 35},
    ],
    marks=[
        nib.SectorMark(
            angle="percentage",
            foreground_style=nib.PlottableField("segment"),
            inner_radius=50,
            outer_radius=100,
        ),
    ],
    width=250,
    height=250,
)

Styled donut with rounded segments¶

import nib

chart = nib.Chart(
    data=[
        {"region": "North", "sales": 120},
        {"region": "South", "sales": 90},
        {"region": "East", "sales": 75},
        {"region": "West", "sales": 110},
    ],
    marks=[
        nib.SectorMark(
            angle="sales",
            foreground_style=nib.PlottableField("region"),
            inner_radius=40,
            outer_radius=80,
            corner_radius=4,
        ),
    ],
    legend=nib.ChartLegend(position="trailing", title="Region"),
    width=300,
    height=300,
    padding=16,
)