ISO8601 digit significance

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
import matplotlib.ticker as ticker
import numpy as np

SECONDS_PER_DAY = 86_400
SECONDS_PER_MONTH = 365.25 * 86_400 / 12
SECONDS_PER_YEAR = 365.25 * 86_400

D1 = SECONDS_PER_DAY
D10 = 10 * SECONDS_PER_DAY
M1 = SECONDS_PER_MONTH
M10 = 10 * SECONDS_PER_MONTH
Y1 = SECONDS_PER_YEAR
Y10 = 10 * SECONDS_PER_YEAR
Y100 = 100 * SECONDS_PER_YEAR
Y1000 = 1000 * SECONDS_PER_YEAR

H1 = 3600
H10 = 10 * 3600
MIN1 = 60
MIN10 = 600
S1 = 1
S10 = 10

# Each tuple: (height_in_seconds, display_label, component)
formats = {
    "yyyy-mm-dd HH:MM:SS": [
        (Y1000, "y\n×1000", "y"),
        (Y100,  "y\n×100",  "y"),
        (Y10,   "y\n×10",   "y"),
        (Y1,    "y\n×1",    "y"),
        (M10,   "m\n×10",   "m"),
        (M1,    "m\n×1",    "m"),
        (D10,   "d\n×10",   "d"),
        (D1,    "d\n×1",    "d"),
        (H10,   "H\n×10",   "h"),
        (H1,    "H\n×1",    "h"),
        (MIN10, "M\n×10",   "n"),
        (MIN1,  "M\n×1",    "n"),
        (S10,   "S\n×10",   "s"),
        (S1,    "S\n×1",    "s"),
    ],
}

COLORS = {
    "y": "#1D6FA4",
    "m": "#1A7A3C",
    "d": "#C2530A",
    "h": "#7B3FA0",
    "n": "#B8860B",
    "s": "#B22222",
}

def sci_label(v):
    if v < 1:
        return rf"$10^{{0}}$"
    exp = int(np.floor(np.log10(v)))
    coeff = v / 10**exp
    if abs(coeff - 1.0) < 0.05:
        return rf"$10^{{{exp}}}$"
    return rf"${coeff:.1f}\times10^{{{exp}}}$"

def sci_tick(v, _=None):
    if v <= 0:
        return ""
    exp = int(np.floor(np.log10(v)))
    return rf"$10^{{{exp}}}$"

fig, axes = plt.subplots(1, 1, figsize=(10, 8))
axes = [axes]
fig.patch.set_facecolor("white")

fig.suptitle(
    "ISO 8601 digit significance",
    fontsize=15, fontweight="bold", color="#111827", y=0.97,
)

YMIN, YMAX = 0.5, 1.5e11

for ax, (title, bars) in zip(axes, formats.items()):
    ax.set_facecolor("#F8FAFC")
    ax.spines[:].set_color("#CBD5E1")
    ax.tick_params(colors="#1E293B")
    ax.yaxis.label.set_color("#1E293B")

    n = len(bars)
    x = np.arange(n)
    heights = [b[0] for b in bars]
    labels  = [b[1] for b in bars]
    comps   = [b[2] for b in bars]
    bar_colors = [COLORS[c] for c in comps]

    rects = ax.bar(x, heights, color=bar_colors, edgecolor="white",
                   linewidth=0.8, zorder=3, width=0.65, alpha=0.88)

    ax.set_yscale("log")
    ax.set_ylim(YMIN, YMAX)
    ax.set_xticks(x)
    ax.set_xticklabels(labels, fontsize=9, color="#1E293B")
    ax.set_title(title, fontsize=12, fontweight="bold", color="#111827", pad=10,
                 fontfamily="monospace")
    ax.grid(axis="y", color="#CBD5E1", linewidth=0.6, zorder=0)

    # Vertical separator between date and time digits
    ax.axvline(x=7.5, color="#94A3B8", linewidth=1.2, linestyle="--", zorder=2)

    for rect, val in zip(rects, heights):
        ax.text(
            rect.get_x() + rect.get_width() / 2,
            val * 2.5,
            sci_label(val),
            ha="center", va="bottom",
            fontsize=8, color="#111827", fontweight="bold",
        )

    ax.yaxis.set_major_formatter(ticker.FuncFormatter(sci_tick))
    ax.yaxis.set_minor_locator(ticker.NullLocator())

    if True:
        ax.set_ylabel("Seconds", color="#1E293B", fontsize=11)
    ax.set_xlabel("Digit position →", color="#64748B", fontsize=9)

patches = [
    mpatches.Patch(color=COLORS["y"], alpha=0.88, label="Year digit"),
    mpatches.Patch(color=COLORS["m"], alpha=0.88, label="Month digit"),
    mpatches.Patch(color=COLORS["d"], alpha=0.88, label="Day digit"),
    mpatches.Patch(color=COLORS["h"], alpha=0.88, label="Hour digit"),
    mpatches.Patch(color=COLORS["n"], alpha=0.88, label="Minute digit"),
    mpatches.Patch(color=COLORS["s"], alpha=0.88, label="Second digit"),
]
fig.legend(
    handles=patches,
    loc="lower center",
    ncol=6,
    fontsize=10,
    framealpha=1.0,
    labelcolor="#111827",
    facecolor="white",
    edgecolor="#CBD5E1",
    bbox_to_anchor=(0.5, 0.01),
)

plt.tight_layout(rect=[0, 0.07, 1, 0.96])
plt.savefig("/workspace/datetime_formats_comparison.png", dpi=150,
            bbox_inches="tight", facecolor=fig.get_facecolor())
print("Saved to /workspace/datetime_formats_comparison.png")