tradeaxis 0.1.1

Matplotlib with market-microstructure sanity: gap compression, LOD decimation, and trader-style interaction.

TradeAxis

Matplotlib with market-microstructure sanity.

TradeAxis is a thin wrapper that composes gap-compression, level-of-detail decimation, and trader-style mouse interaction onto a standard matplotlib Axes. No subclassing, no new API to learn -- your ax stays a normal ax.

Features

• Gap compression -- Overnight/weekend gaps are detected automatically and removed. Session breaks are marked with clean dashed separators.
• LOD decimation -- Millions of points render instantly. On zoom, the visible data is refined to full resolution. Min/max bucket downsampling ensures spikes are never hidden.
• Trader-style interaction -- Left-drag to pan, right-drag to zoom, middle-click for a snap-to-data crosshair with datetime + value annotation. Press Escape to dismiss.

Installation

pip install tradeaxis

Or with Poetry (from source):

git clone https://github.com/youruser/tradeaxis.git
cd tradeaxis
poetry install

Quick start

import matplotlib.pyplot as plt
import numpy as np
import tradeaxis as ta

# Generate synthetic multi-day 1-min data
def make_day(date):
    base = np.datetime64(date)
    start = base + np.timedelta64(9 * 60 + 30, "m")
    end = base + np.timedelta64(16 * 60, "m")
    return np.arange(start, end, np.timedelta64(1, "m"))

timestamps = np.concatenate([make_day("2026-01-05"), make_day("2026-01-06")])
prices = 150 + np.cumsum(np.random.randn(len(timestamps)) * 0.02)

# One line to enhance the axes
fig, ax = plt.subplots(figsize=(14, 5))
chart = ta.wrap(ax, timestamps, prices)

# Everything below is normal matplotlib
ax.set_title("AAPL 1-min")
ax.set_ylabel("Price ($)")
ax.axhline(prices.mean(), color="red", ls="--", alpha=0.5, label="Mean")
ax.legend()
plt.show()

Interaction controls

Action	Effect
Left-drag	Pan along the x-axis
Right-drag up	Zoom in (centered at cursor)
Right-drag down	Zoom out (centered at cursor)
Middle-click	Snap crosshair to nearest data point, show datetime + value
Escape	Dismiss crosshair

API reference

tradeaxis.wrap(ax, timestamps, values, *, gap="auto", show_separators=True, interaction=True)

Enhance a standard matplotlib Axes with gap compression, LOD decimation, and interaction.

Parameters:

Name	Type	Default	Description
ax	matplotlib.axes.Axes	--	The axes to enhance.
timestamps	array[datetime64]	--	Sorted timestamps.
values	array[float]	--	Y-values (prices, volumes, etc.).
gap	"auto" / timedelta / callable	"auto"	Gap detection strategy. "auto" uses median heuristic. A timedelta sets a fixed threshold. A callable receives the timestamps array and returns a boolean mask.
show_separators	bool	True	Draw dashed vertical lines at session breaks.
interaction	bool	True	Enable pan/zoom/crosshair mouse handling.

Returns: Chart -- a handle for the enhanced chart. The ax is still a normal matplotlib Axes.

tradeaxis.plot_intraday(timestamps, values, *, gap="auto", show_separators=True, interaction=True, figsize=(14, 6))

Convenience function that creates a new figure + axes and calls wrap().

Chart methods

Method	Description
chart.to_index(datetime)	Convert a datetime to compressed index space (for adding custom annotations).
chart.to_datetime(idx)	Convert a compressed index back to a datetime.
chart.detach()	Remove all TradeAxis artifacts and restore the axes to vanilla matplotlib.

Working with compressed x-axis

The x-axis uses a compressed integer index, not wall-clock time. This means distances are proportional to number of data points, not elapsed time. When adding custom annotations:

# Convert a datetime to index space, then annotate normally
idx = chart.to_index(np.datetime64("2026-01-05T12:00"))
ax.axvline(x=idx, color="green", ls=":")

How it works

1. TimeMapping detects gaps in the timestamp sequence (via median-heuristic or user-specified threshold) and remaps datetimes to a contiguous integer index. A FuncFormatter maps these integers back to readable time labels on the x-axis.

2. LODRenderer decimates large datasets using min/max bucket downsampling. For each bucket of points, only the minimum and maximum values are kept (interleaved in x-order), preserving spikes. An LRU cache avoids recomputation during repeated pans.

3. InteractionController implements a simple state machine (IDLE -> PAN / ZOOM) over matplotlib canvas events. The crosshair snaps to the nearest data point via binary search.

All of this is composed onto a user-owned Axes via callbacks and artist injection -- no subclassing, no monkey-patching.

Development

poetry install
poetry run pytest -v

Examples notebook:

poetry run jupyter notebook examples/showcase.ipynb

License

MIT