# Profile: Charts · Matplotlib. Choose a safe display range from current data.
import matplotlib.pyplot as plt

def chart_values(labels, cents):
    if len(labels) != len(cents):
        raise ValueError("each label needs one value")
    values = []
    for amount in cents:
        values.append(amount / 100)
    largest = 0.0
    for value in values:
        if value > largest:
            largest = value
    upper = max(1.0, largest * 1.2)
    fig, ax = plt.subplots(figsize=(6, 3.5), layout="constrained")
    ax.bar(labels, values, color="#2563eb")
    ax.set(title="Synthetic accepted subtotal", xlabel="Category",
           ylabel="Fictional currency units", ylim=(0, upper))
    if len(values) == 0:
        ax.text(0.5, 0.5, "No accepted records", transform=ax.transAxes,
                ha="center")
    total = sum(cents) / 100
    print(f"Subtotal: {total:.2f}; y-axis upper bound: {upper}")
    return fig, ax

fig, ax = chart_values(["Pens", "Paper"], [14000, 2000])
assert ax.get_ylim()[1] > 140
fig.savefig("changed_values.png", dpi=160)
# Run again with labels=[], cents=[], or with two zero values. Explain each.