Plotly: Interactive Graphing Library

Overview Plotly (specifically plotly.express and plotly.graph_objects) is a graphing library that makes interactive, publication-quality graphs. Unlike Matplotlib (static images), Plotly graphs are rendered in JavaScript (D3.js stack) and allow zooming, panning, and hovering.

Key Features

1. Interactivity by Default In a Jupyter Notebook or Web App (Streamlit/Dash), users can hover over points to see exact values.

2. High-Level API (Plotly Express) Create complex charts in one line.

import plotly.express as px
df = px.data.iris()
fig = px.scatter(df, x="sepal_width", y="sepal_length", color="species")
fig.show()

3. Dashboards Plotly is the rendering engine for Dash and Streamlit, making it the standard for Python Data Apps.

Chart Types

• Basic: Line, Bar, Scatter, Pie.
• Statistical: Box, Violin, Histogram, Heatmap.
• Scientific: 3D Surface, Contour, Log plots.
• Maps: Choropleth, Scatter Geo (using Mapbox).
• Financial: Candlestick charts.

Plotly vs Matplotlib

• Matplotlib: Better for static papers (PDF/EPS). Precise control.
• Plotly: Better for web, presentations, and exploration.

Rendering It works entirely offline but creates HTML files or renders inline in Notebooks.