Skip to content

Latest commit

 

History

History
310 lines (258 loc) · 6.8 KB

marker-style.md

File metadata and controls

310 lines (258 loc) · 6.8 KB
jupyter
jupytext kernelspec language_info plotly
notebook_metadata_filter text_representation
all
extension format_name format_version jupytext_version
.md
markdown
1.1
1.1.7
display_name language name
Python 3
python
python3
codemirror_mode file_extension mimetype name nbconvert_exporter pygments_lexer version
name version
ipython
3
.py
text/x-python
python
python
ipython3
3.6.5
description display_as language layout name order permalink thumbnail
How to style markers in Python with Plotly.
file_settings
python
base
Styling Markers
19
python/marker-style/
thumbnail/marker-style.gif

Add Marker Border

In order to make markers look more distinct, you can add a border to the markers. This can be achieved by adding the line property to the marker object.

Here is an example of adding a marker border to a faceted scatter plot created using Plotly Express.

import plotly.express as px

df = px.data.iris()
fig = px.scatter(df, x="sepal_width", y="sepal_length", color="species")

fig.update_traces(marker=dict(size=12,
                              line=dict(width=2,
                                        color='DarkSlateGrey')),
                  selector=dict(mode='markers'))
fig.show()

Here is an example that creates an empty graph object figure, and then adds two scatter traces with a marker border.

import plotly.graph_objects as go

# Generate example data
import numpy as np
np.random.seed(1)

x = np.random.uniform(low=3, high=6, size=(500,))
y = np.random.uniform(low=3, high=6, size=(500,))

# Build figure
fig = go.Figure()

# Add scatter trace with medium sized markers
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=x,
        y=y,
        marker=dict(
            color='LightSkyBlue',
            size=20,
            line=dict(
                color='MediumPurple',
                width=2
            )
        ),
        showlegend=False
    )
)

# Add trace with large marker
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=[2],
        y=[4.5],
        marker=dict(
            color='LightSkyBlue',
            size=120,
            line=dict(
                color='MediumPurple',
                width=12
            )
        ),
        showlegend=False
    )
)

fig.show()

Fully opaque, the default setting, is useful for non-overlapping markers. When many points overlap it can be hard to observe density.

Opacity

Setting opacity outside the marker will set the opacity of the trace. Thus, it will allow greater visbility of additional traces but like fully opaque it is hard to distinguish density.

import plotly.graph_objects as go

# Generate example data
import numpy as np

x = np.random.uniform(low=3, high=6, size=(500,))
y = np.random.uniform(low=3, high=4.5, size=(500,))
x2 = np.random.uniform(low=3, high=6, size=(500,))
y2 = np.random.uniform(low=4.5, high=6, size=(500,))

# Build figure
fig = go.Figure()

# Add first scatter trace with medium sized markers
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=x,
        y=y,
        opacity=0.5,
        marker=dict(
            color='LightSkyBlue',
            size=20,
            line=dict(
                color='MediumPurple',
                width=2
            )
        ),
        name='Opacity 0.5'
    )
)

# Add second scatter trace with medium sized markers
# and opacity 1.0
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=x2,
        y=y2,
        marker=dict(
            color='LightSkyBlue',
            size=20,
            line=dict(
                color='MediumPurple',
                width=2
            )
        ),
        name='Opacity 1.0'
    )
)

# Add trace with large markers
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=[2, 2],
        y=[4.25, 4.75],
        opacity=0.5,
        marker=dict(
            color='LightSkyBlue',
            size=80,
            line=dict(
                color='MediumPurple',
                width=8
            )
        ),
        showlegend=False
    )
)

fig.show()

Marker Opacity

To maximise visibility of density, it is recommended to set the opacity inside the marker marker:{opacity:0.5}. If mulitple traces exist with high density, consider using marker opacity in conjunction with trace opacity.

import plotly.graph_objects as go

# Generate example data
import numpy as np

x = np.random.uniform(low=3, high=6, size=(500,))
y = np.random.uniform(low=3, high=6, size=(500,))

# Build figure
fig = go.Figure()

# Add scatter trace with medium sized markers
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=x,
        y=y,
        marker=dict(
            color='LightSkyBlue',
            size=20,
            opacity=0.5,
            line=dict(
                color='MediumPurple',
                width=2
            )
        ),
        showlegend=False
    )
)


# Add trace with large markers
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=[2, 2],
        y=[4.25, 4.75],
        marker=dict(
            color='LightSkyBlue',
            size=80,
            opacity=0.5,
            line=dict(
                color='MediumPurple',
                width=8
            )
        ),
        showlegend=False
    )
)

fig.show()

Color Opacity

To maximise visibility of each point, set the color as an rgba string that includes an alpha value of 0.5.

This example sets the marker color to 'rgba(135, 206, 250, 0.5)'. The rgb values of 135, 206, and 250 are from the definition of the LightSkyBlue named CSS color that is is used in the previous examples (See https://www.color-hex.com/color/87cefa). The marker line will remain opaque.

import plotly.graph_objects as go

# Generate example data
import numpy as np

x = np.random.uniform(low=3, high=6, size=(500,))
y = np.random.uniform(low=3, high=6, size=(500,))


# Build figure
fig = go.Figure()

# Add scatter trace with medium sized markers
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=x,
        y=y,
        marker=dict(
            color='rgba(135, 206, 250, 0.5)',
            size=20,
            line=dict(
                color='MediumPurple',
                width=2
            )
        ),
        showlegend=False
    )
)


# Add trace with large markers
fig.add_trace(
    go.Scatter(
        mode='markers',
        x=[2, 2],
        y=[4.25, 4.75],
        marker=dict(
            color='rgba(135, 206, 250, 0.5)',
            size=80,
            line=dict(
                color='MediumPurple',
                width=8
            )
        ),
        showlegend=False
    )
)

fig.show()

Reference

See https://plot.ly/python/reference/ for more information and chart attribute options!