Plotly

---
name: plotly
description: Interactive scientific and statistical data visualization library for Python. Use when creating charts, plots, or visualizations including scatter plots, line charts, bar charts, heatmaps, 3D plots, geographic maps, statistical distributions, financial charts, and dashboards. Supports both quick visualizations (Plotly Express) and fine-grained customization (graph objects). Outputs interactive HTML or static images (PNG, PDF, SVG).
---

# Plotly

Python graphing library for creating interactive, publication-quality visualizations with 40+ chart types.

## Quick Start

Install Plotly:
```bash
uv pip install plotly
```

Basic usage with Plotly Express (high-level API):
```python
import plotly.express as px
import pandas as pd

df = pd.DataFrame({
    'x': [1, 2, 3, 4],
    'y': [10, 11, 12, 13]
})

fig = px.scatter(df, x='x', y='y', title='My First Plot')
fig.show()
```

## Choosing Between APIs

### Use Plotly Express (px)
For quick, standard visualizations with sensible defaults:
- Working with pandas DataFrames
- Creating common chart types (scatter, line, bar, histogram, etc.)
- Need automatic color encoding and legends
- Want minimal code (1-5 lines)

See [reference/plotly-express.md](reference/plotly-express.md) for complete guide.

### Use Graph Objects (go)
For fine-grained control and custom visualizations:
- Chart types not in Plotly Express (3D mesh, isosurface, complex financial charts)
- Building complex multi-trace figures from scratch
- Need precise control over individual components
- Creating specialized visualizations with custom shapes and annotations

See [reference/graph-objects.md](reference/graph-objects.md) for complete guide.

**Note:** Plotly Express returns graph objects Figure, so you can combine approaches:
```python
fig = px.scatter(df, x='x', y='y')
fig.update_layout(title='Custom Title')  # Use go methods on px figure
fig.add_hline(y=10)                     # Add shapes
```

## Core Capabilities

### 1. Chart Types

Plotly supports 40+ chart types organized into categories:

**Basic Charts:** scatter, line, bar, pie, area, bubble

**Statistical Charts:** histogram, box plot, violin, distribution, error bars

**Scientific Charts:** heatmap, contour, ternary, image display

**Financial Charts:** candlestick, OHLC, waterfall, funnel, time series

**Maps:** scatter maps, choropleth, density maps (geographic visualization)

**3D Charts:** scatter3d, surface, mesh, cone, volume

**Specialized:** sunburst, treemap, sankey, parallel coordinates, gauge

For detailed examples and usage of all chart types, see [reference/chart-types.md](reference/chart-types.md).

### 2. Layouts and Styling

**Subplots:** Create multi-plot figures with shared axes:
```python
from plotly.subplots import make_subplots
import plotly.graph_objects as go

fig = make_subplots(rows=2, cols=2, subplot_titles=('A', 'B', 'C', 'D'))
fig.add_trace(go.Scatter(x=[1, 2], y=[3, 4]), row=1, col=1)
```

**Templates:** Apply coordinated styling:
```python
fig = px.scatter(df, x='x', y='y', template='plotly_dark')
# Built-in: plotly_white, plotly_dark, ggplot2, seaborn, simple_white
```

**Customization:** Control every aspect of appearance:
- Colors (discrete sequences, continuous scales)
- Fonts and text
- Axes (ranges, ticks, grids)
- Legends
- Margins and sizing
- Annotations and shapes

For complete layout and styling options, see [reference/layouts-styling.md](reference/layouts-styling.md).

### 3. Interactivity

Built-in interactive features:
- Hover tooltips with customizable data
- Pan and zoom
- Legend toggling
- Box/lasso selection
- Rangesliders for time series
- Buttons and dropdowns
- Animations

```python
# Custom hover template
fig.update_traces(
    hovertemplate='<b>%{x}</b><br>Value: %{y:.2f}<extra></extra>'
)

# Add rangeslider
fig.update_xaxes(rangeslider_visible=True)

# Animations
fig = px.scatter(df, x='x', y='y', animation_frame='year')
```

For complete interactivity guide, see [reference/export-interactivity.md](reference/export-interactivity.md).

### 4. Export Options

**Interactive HTML:**
```python
fig.write_html('chart.html')                       # Full standalone
fig.write_html('chart.html', include_plotlyjs='cdn')  # Smaller file
```

**Static Images (requires kaleido):**
```bash
uv pip install kaleido
```

```python
fig.write_image('chart.png')   # PNG
fig.write_image('chart.pdf')   # PDF
fig.write_image('chart.svg')   # SVG
```

For complete export options, see [reference/export-interactivity.md](reference/export-interactivity.md).

## Common Workflows

### Scientific Data Visualization

```python
import plotly.express as px

# Scatter plot with trendline
fig = px.scatter(df, x='temperature', y='yield', trendline='ols')

# Heatmap from matrix
fig = px.imshow(correlation_matrix, text_auto=True, color_continuous_scale='RdBu')

# 3D surface plot
import plotly.graph_objects as go
fig = go.Figure(data=[go.Surface(z=z_data, x=x_data, y=y_data)])
```

### Statistical Analysis

```python
# Distribution comparison
fig = px.histogram(df, x='values', color='group', marginal='box', nbins=30)

# Box plot with all points
fig = px.box(df, x='category', y='value', points='all')

# Violin plot
fig = px.violin(df, x='group', y='measurement', box=True)
```

### Time Series and Financial

```python
# Time series with rangeslider
fig = px.line(df, x='date', y='price')
fig.update_xaxes(rangeslider_visible=True)

# Candlestick chart
import plotly.graph_objects as go
fig = go.Figure(data=[go.Candlestick(
    x=df['date'],
    open=df['open'],
    high=df['high'],
    low=df['low'],
    close=df['close']
)])
```

### Multi-Plot Dashboards

```python
from plotly.subplots import make_subplots
import plotly.graph_objects as go

fig = make_subplots(
    rows=2, cols=2,
    subplot_titles=('Scatter', 'Bar', 'Histogram', 'Box'),
    specs=[[{'type': 'scatter'}, {'type': 'bar'}],
           [{'type': 'histogram'}, {'type': 'box'}]]
)

fig.add_trace(go.Scatter(x=[1, 2, 3], y=[4, 5, 6]), row=1, col=1)
fig.add_trace(go.Bar(x=['A', 'B'], y=[1, 2]), row=1, col=2)
fig.add_trace(go.Histogram(x=data), row=2, col=1)
fig.add_trace(go.Box(y=data), row=2, col=2)

fig.update_layout(height=800, showlegend=False)
```

## Integration with Dash

For interactive web applications, use Dash (Plotly's web app framework):

```bash
uv pip install dash
```

```python
import dash
from dash import dcc, html
import plotly.express as px

app = dash.Dash(__name__)

fig = px.scatter(df, x='x', y='y')

app.layout = html.Div([
    html.H1('Dashboard'),
    dcc.Graph(figure=fig)
])

app.run_server(debug=True)
```

## Reference Files

- **[plotly-express.md](reference/plotly-express.md)** - High-level API for quick visualizations
- **[graph-objects.md](reference/graph-objects.md)** - Low-level API for fine-grained control
- **[chart-types.md](reference/chart-types.md)** - Complete catalog of 40+ chart types with examples
- **[layouts-styling.md](reference/layouts-styling.md)** - Subplots, templates, colors, customization
- **[export-interactivity.md](reference/export-interactivity.md)** - Export options and interactive features

## Additional Resources

- Official documentation: https://plotly.com/python/
- API reference: https://plotly.com/python-api-reference/
- Community forum: https://community.plotly.com/