hadcrut5_bars.py

#!/usr/bin/python3
# Copyright (c) 2020-2024 Davide Madrisan <d.madrisan@proton.me>
# SPDX-License-Identifier: GPL-3.0-or-later

"""
Display a bar plot of the HadCRUT5 Global temperature dataset.
"""

import argparse

import matplotlib.pyplot as plt
import matplotlib.colors

from hadcrut5lib import argparser, HadCRUT5


def parse_args() -> argparse.Namespace:
    """This function parses and return arguments passed in"""
    descr = "Parse and plot the HadCRUT5 temperature datasets"
    examples = [
        "%(prog)s",
        '%(prog)s --period "1850-1900"',
        '%(prog)s --period "1880-1920"',
        "%(prog)s --outfile HadCRUT5-global.png",
    ]

    parser = argparser(descr, examples)
    parser.add_argument(
        "-f",
        "--outfile",
        action="store",
        dest="outfile",
        help="name of the output PNG file",
    )
    parser.add_argument(
        "-p",
        "--period",
        action="store",
        dest="period",
        default="1961-1990",
        help="show anomalies related to 1961-1990 (default), 1850-1900, or 1880-1920",
    )
    parser.add_argument(
        "-v",
        "--verbose",
        action="store_true",
        dest="verbose",
        help="make the operation more talkative",
    )

    return parser.parse_args()


# mypy: disable-error-code="misc, attr-defined"
def plotbar(period: str, outfile: str, verbose: bool):
    """
    Create a bar plot for the specified period and diplay it or save it to file
    if outfile is set
    """

    # pylint: disable=W0613
    def major_formatter(x, pos):
        return f"{x:.1f}" if x >= 0 else ""

    # pylint: enable=W0613

    hc5 = HadCRUT5(period=period, verbose=verbose)
    hc5.datasets_download()
    hc5.datasets_load()
    hc5.datasets_normalize()

    years = hc5.dataset_years()
    _, mean, _ = hc5.dataset_normalized_data(hc5.GLOBAL_REGION)

    bar_width = 0.7
    basefont = {
        "family": "DejaVu Sans",
        "color": "white",
        "weight": "bold",
    }
    fontxl = {**basefont, "size": 20}
    fontxs = {**basefont, "size": 12}

    plt.style.use("dark_background")
    _, ax = plt.subplots()

    # pylint: disable=no-member
    cmap = plt.cm.jet  # or plt.cm.bwr
    norm = matplotlib.colors.Normalize(vmin=-1, vmax=max(mean))
    colors = cmap(norm(mean))

    ax.bar(years, mean, width=bar_width, color=colors, align="center")

    ax.set_frame_on(False)
    ax.yaxis.tick_right()
    ax.yaxis.set_major_formatter(major_formatter)
    ax.tick_params(axis="both", which="both", length=0)

    upper, left = 0.95, 0.025
    last_year = years[-1]
    text_props = {
        "horizontalalignment": "left",
        "verticalalignment": "top",
        "transform": ax.transAxes,
    }
    plt.text(
        left,
        upper,
        "\n".join((r"Global average temperature difference *", f"1850-{last_year}")),
        fontdict=fontxl,
        linespacing=1.2,
        **text_props,
    )
    plt.text(
        left,
        upper - 0.125,
        "\n".join(
            (
                f"(*) Compared to {period} pre-industrial levels",
                r"Data source - HadCRUT5",
            )
        ),
        fontdict=fontxs,
        linespacing=1.5,
        **text_props,
    )

    fig = plt.gcf()
    fig.set_size_inches(10, 8)  # 1 inch equal to 80pt

    if outfile:
        fig.savefig(outfile, dpi=80, bbox_inches="tight")
        plt.close(fig)
    else:
        plt.show()


# pylint: disable=C0116
def main():
    args = parse_args()

    plotbar(args.period, args.outfile, args.verbose)


main()