PointMark

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Displays individual data points as symbols, ideal for scatter plots and showing relationships between two quantitative variables. Each point can be customized with different shapes, sizes, and colors.

PointMark is commonly used for scatter plots, bubble charts (with size encoding), and adding data point markers to other chart types.

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

Constructor

nib.PointMark(
    x,
    y,
    foreground_style=None,
    symbol=None,
    symbol_size=None,
    opacity=None,
)

Parameters

Parameter Type Default Description
x str \| PlottableField required Data field for the x-axis position.
y str \| PlottableField required Data field for the y-axis position.
foreground_style str \| PlottableField None Point fill color. Accepts hex strings, named colors, or a PlottableField to color points by category.
symbol SymbolShape \| str \| PlottableField None Shape of the point marker. Use a SymbolShape enum (CIRCLE, SQUARE, TRIANGLE, DIAMOND, CROSS, PLUS, PENTAGON, HEXAGON), a string, or a PlottableField to vary symbols by data category.
symbol_size float None Size of the symbol in square points. Larger values create bigger markers. Uses system default when not specified.
opacity float None Opacity from 0.0 to 1.0. Useful for dense scatter plots where points overlap.

Examples

Basic scatter plot

import nib

def main(app: nib.App):
    chart = nib.Chart(
        data=[
            {"height": 165, "weight": 60},
            {"height": 170, "weight": 72},
            {"height": 175, "weight": 80},
            {"height": 180, "weight": 85},
            {"height": 160, "weight": 55},
        ],
        marks=[nib.PointMark(x="height", y="weight")],
        x_axis=nib.ChartAxis(label="Height (cm)"),
        y_axis=nib.ChartAxis(label="Weight (kg)"),
        width=300,
        height=250,
    )
    app.build(chart)

nib.run(main)

Colored by category

import nib

data = [
    {"x": 5.1, "y": 3.5, "species": "Setosa"},
    {"x": 7.0, "y": 3.2, "species": "Versicolor"},
    {"x": 6.3, "y": 3.3, "species": "Virginica"},
]

chart = nib.Chart(
    data=data,
    marks=[
        nib.PointMark(
            x="x",
            y="y",
            foreground_style=nib.PlottableField("species"),
        ),
    ],
    legend=nib.ChartLegend(position="bottom"),
    width=400,
    height=300,
)

Custom symbols and size

import nib

chart = nib.Chart(
    data=measurements,
    marks=[
        nib.PointMark(
            x="x",
            y="y",
            symbol=nib.SymbolShape.DIAMOND,
            symbol_size=100,
            foreground_style="#EF4444",
        ),
    ],
    width=350,
    height=250,
)

Symbols varying by data

import nib

chart = nib.Chart(
    data=multi_category_data,
    marks=[
        nib.PointMark(
            x="x",
            y="y",
            symbol=nib.PlottableField("category"),
            foreground_style=nib.PlottableField("category"),
        ),
    ],
    width=400,
    height=300,
)
AreaMark RuleMark