Unmasking the Colors of Plotly: Finding the Default Palette
Plotly, a powerful data visualization library, is known for its visually appealing and interactive charts. One aspect that contributes to this aesthetic appeal is the default color palette used for its plots. But where exactly is this color palette defined, and how can you access it?
Let's delve into the fascinating world of Plotly colors and find the answers.
The Search Begins
Imagine you're creating a series of charts in Plotly. You want to maintain a consistent color scheme across these plots, but you don't want to manually define each color for every trace. Wouldn't it be great to easily access and leverage the default colors used by Plotly?
Exploring the Source
The default color palette in Plotly is not explicitly defined as a separate variable or function. Instead, it's woven into the fabric of the library's core functionality. This means that the colors are assigned dynamically based on the number of traces in your plot.
To understand how this works, let's examine the plotly.graph_objects module, which is the foundation for creating Plotly figures. Here's a simplified example demonstrating this dynamic color assignment:
import plotly.graph_objects as go
fig = go.Figure()
fig.add_trace(go.Scatter(x=[1, 2, 3], y=[4, 5, 6], name="Trace 1"))
fig.add_trace(go.Scatter(x=[1, 2, 3], y=[7, 8, 9], name="Trace 2"))
fig.show()
In this snippet, we've created a figure with two traces. Plotly will automatically assign colors to these traces from its internal color palette.
Unveiling the Secrets
While you can't directly access the default color palette as a standalone entity, you can uncover its structure through the plotly.colors module. This module offers several utilities, including the qualitative.Plotly palette. Let's break down this palette:
import plotly.colors as pc
print(pc.qualitative.Plotly)
Output:
['#636EFA', '#EF553B', '#00CC96', '#AB63FA', '#FFA15A', '#19D3F3', '#FF6692', '#B6E880', '#FF97FF', '#FECB52']
This output reveals the ten default colors used by Plotly for its charts. You can see the familiar blue, orange, green, and other colors that define the Plotly aesthetic.
Using the Colors
You can directly leverage these colors in your plots. For instance, if you want to use the second color in the qualitative.Plotly palette, you can simply access it by index:
import plotly.graph_objects as go
import plotly.colors as pc
fig = go.Figure()
fig.add_trace(go.Scatter(x=[1, 2, 3], y=[4, 5, 6], name="Trace 1", marker_color=pc.qualitative.Plotly[1]))
fig.show()
In this case, marker_color will be set to #EF553B, the second color in the palette.
Conclusion
While Plotly's default color palette is not explicitly defined, you can easily extract its colors for custom color assignments. Using the plotly.colors module, you can access the qualitative.Plotly palette and use its individual colors to create consistent and aesthetically pleasing visualizations. By understanding how Plotly handles colors, you can tailor your charts to match your desired aesthetic.
