mgplot 0.2.27

mgplot is a time-series/PeriodIndex frontend for matplotlib

mgplot

Description

mgplot is an open-source Python frontend for matplotlib designed for time-series chart creation with PeriodIndex data. It simplifies common economic and financial plots while:

1. producing time-series charts that can be tricky to create directly,
2. finalising (or publishing) charts with titles, labels, annotations, etc.,
3. minimising code duplication, and maintaining a consistent style.

Installation

pip install mgplot

Or using uv:

uv add mgplot

Requirements: Python 3.10+, pandas, matplotlib, numpy

Import

import mgplot as mg

Quick Example

import pandas as pd
import mgplot as mg

# Create sample data with PeriodIndex
data = pd.Series(
    [100, 102, 105, 103, 108],
    index=pd.period_range("2024Q1", periods=5, freq="Q")
)

# Plot and finalise in one step
mg.line_plot_finalise(data, title="Quarterly Data", ylabel="Value")

Plot Functions

All plot functions take a pandas Series or DataFrame with a PeriodIndex as the first argument and return a matplotlib Axes object. Keyword arguments control styling and behavior:

• bar_plot() -- bar plot (grouped or stacked) with intelligent PeriodIndex labeling; horizontal=True plots categorical data as horizontal bars (categories on the y-axis, values along the x-axis)
• fill_between_plot() -- shaded region between two bounds (requires 2-column DataFrame)
• growth_plot() -- plots annual and periodic growth rates (requires 2-column DataFrame with pre-calculated growth)
• line_plot() -- one or more lines with optional annotations
• postcovid_plot() -- data as a line with pre-COVID linear projection
• revision_plot() -- designed to plot ABS-style data revisions
• run_plot() -- line plot with background highlighting for monotonic increasing/decreasing runs
• seastrend_plot() -- seasonal and trend components on one plot
• series_growth_plot() -- calculates and plots annual (line) and periodic (bars) growth from a single Series
• summary_plot() -- latest data point against historical range with z-score visualization

For ranked-category charts (states, industries, expenditure classes), use horizontal=True with a string-indexed Series or DataFrame:

vacancies = vacancies.sort_values()  # smallest at the bottom
mg.bar_plot_finalise(
    vacancies,
    horizontal=True,
    annotate=True,     # value labels at the bar ends
    above=True,
    x0=True,           # zero line on the value axis
    title="Job vacancies by industry",
    xlabel="'000",
)

horizontal=True is for categorical data: with a PeriodIndex it warns and falls back to a vertical plot.

Finalising Plots

Once a plot is generated, finalise it with titles, labels, and save to file:

ax = mg.line_plot(data)
mg.finalise_plot(ax, title="My Chart", ylabel="Units", tag="my_chart")

Axis Tick Labels

For PeriodIndex data, x-axis tick labels are generated contextually: the tick density is chosen to fit within max_ticks, and labels show the period with years marked at transitions (e.g. a monthly axis shows Feb Mar ... 2024 ... Feb, a quarterly axis shows Q2 Q3 2025 Q2).

Three keyword arguments control the labels on the period-indexed plot functions (line_plot, bar_plot, growth_plot, fill_between_plot, run_plot, and their *_finalise variants):

• max_ticks -- the maximum number of ticks (suggestive, not exact). The global default is mg.get_setting("max_ticks").
• tick_relabel -- a callable applied to each generated label string, after the contextual labelling has run. Use it to restyle labels without losing the transition logic.
• label_rotation -- (bar_plot only) rotates the x-axis tick labels.

For example, to convert 4-digit year labels to 2-digit years:

import re

def two_digit_years(label: str) -> str:
    """Shorten 4-digit years to 2 digits (e.g. 2024 -> 24)."""
    return re.sub(r"\b(?:19|20)(\d{2})\b", r"\1", label)

# default labels:           2010  2012  2014  ...  2024  2026
# with tick_relabel:          10    12    14  ...    24    26
mg.line_plot_finalise(data, title="My Chart", tick_relabel=two_digit_years)

Because tick_relabel operates on the label strings, this works unchanged on quarterly or monthly axes too: a label such as 2024 marking a year transition becomes 24, while the Q2/Mar labels between transitions pass through untouched.

These options are stashed on the matplotlib Axes when the plot is drawn, and finalise_plot() honours them when it refreshes the tick labels just before saving. Editing tick labels directly on the Axes (e.g. with set_xticklabels()) does not survive that refresh -- use tick_relabel instead.

Multi-Panel Figures

finalise_plot() works on a single Axes. For a figure with several panels, finalise each panel with axes_only=True (axes-level styling only: titles, labels, legends), then make the last call a normal finalise_plot() carrying the figure-level arguments (suptitle, lfooter, rfooter, figsize, ...), which also saves and closes the figure:

fig, (ax_left, ax_right) = plt.subplots(1, 2)
mg.line_plot(left_data, ax=ax_left)
mg.line_plot(right_data, ax=ax_right)
mg.finalise_plot(ax_left, title="Left Panel", ylabel="Index", axes_only=True)
mg.finalise_plot(
    ax_right,
    title="Right Panel",
    ylabel="Index",
    suptitle="Both Panels Together",  # also used for the filename
    lfooter="Australia. Seasonally adjusted.",
    rfooter="Source: ABS",
    figsize=(9, 4.5),
)

Convenience Finalisers

For every plot function, there is a *_finalise() variant that combines the plot and finalise steps:

• bar_plot_finalise()
• fill_between_plot_finalise()
• growth_plot_finalise()
• line_plot_finalise()
• postcovid_plot_finalise()
• revision_plot_finalise()
• run_plot_finalise()
• seastrend_plot_finalise()
• series_growth_plot_finalise()
• summary_plot_finalise()

Multi-Plot Chaining

Chain plotting operations together for batch processing:

• plot_then_finalise() -- chains a plot function with finalise_plot()
• multi_start() -- creates multiple plots with different start dates
• multi_column() -- creates separate plots for each DataFrame column

Settings and Configuration

Manage global defaults for figure size, colors, output directory, etc.:

mg.set_setting("figsize", (10, 5))
mg.set_setting("dpi", 150)
mg.set_chart_dir("./charts")

# Get current setting
current_dpi = mg.get_setting("dpi")

Color Utilities

Built-in support for Australian state/territory and political party colors:

mg.get_color("NSW")           # Returns 'deepskyblue'
mg.get_color("Labor")         # Returns Labor party color
mg.colorise_list(["NSW", "VIC", "QLD"])  # Returns list of colors

Documentation

API documentation is generated from docstrings using pdoc. To view locally:

# Generate and serve docs
uv run pdoc src/mgplot

# Or open the pre-built docs
open docs/mgplot.html

Development

# Install dependencies
uv sync

# Run type checking
uv run pyright src/

# Run linting
uv run ruff check src/
uv run ruff format src/

License

MIT License - see LICENSE file for details.

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