ISO8601 date comparison

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   # average ~2,629,800
SECONDS_PER_YEAR = 365.25 * 86_400          # average ~31,557,600

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

# Each tuple: (height_in_seconds, display_label, component)
# component: 'y', 'm', 'd'
formats = {
    "yyyy-mm-dd (ISO 8601)": [
        (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"),
    ],
    "dd-mm-yyyy": [
        (D10,   "d\n×10",   "d"),
        (D1,    "d\n×1",    "d"),
        (M10,   "m\n×10",   "m"),
        (M1,    "m\n×1",    "m"),
        (Y1000, "y\n×1000", "y"),
        (Y100,  "y\n×100",  "y"),
        (Y10,   "y\n×10",   "y"),
        (Y1,    "y\n×1",    "y"),
    ],
    "mm/dd/yyyy": [
        (M10,   "m\n×10",   "m"),
        (M1,    "m\n×1",    "m"),
        (D10,   "d\n×10",   "d"),
        (D1,    "d\n×1",    "d"),
        (Y1000, "y\n×1000", "y"),
        (Y100,  "y\n×100",  "y"),
        (Y10,   "y\n×10",   "y"),
        (Y1,    "y\n×1",    "y"),
    ],
}

COLORS = {"y": "#1D6FA4", "m": "#1A7A3C", "d": "#C2530A"}

def sci_label(v):
    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):
    exp = int(np.floor(np.log10(v)))
    return rf"$10^{{{exp}}}$"

fig, axes = plt.subplots(1, 3, figsize=(18, 8), sharey=True)
fig.patch.set_facecolor("white")

fig.suptitle(
    "Date Format Comparison",
    fontsize=15, fontweight="bold", color="#111827", y=0.97,
)

YMIN, YMAX = 3e4, 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")

    x = np.arange(8)
    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=9.5, color="#1E293B")
    ax.set_title(title, fontsize=13, fontweight="bold", color="#111827", pad=10)
    ax.grid(axis="y", color="#CBD5E1", linewidth=0.6, zorder=0)

    # Annotate each bar with scientific notation
    for rect, val in zip(rects, heights):
        ax.text(
            rect.get_x() + rect.get_width() / 2,
            val * 2.0,
            sci_label(val),
            ha="center", va="bottom",
            fontsize=8.5, color="#111827", fontweight="bold",
        )

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

    if ax == axes[0]:
        ax.set_ylabel("Seconds (log scale)", color="#1E293B", fontsize=11)
    ax.set_xlabel("Digit position →", color="#64748B", fontsize=9)

# Legend
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"),
]
fig.legend(
    handles=patches,
    loc="lower center",
    ncol=4,
    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/date_formats_comparison.png", dpi=150,
            bbox_inches="tight", facecolor=fig.get_facecolor())
print("Saved to /workspace/date_formats_comparison.png")