Fine-Tune Your Matplotlib Legends for Perfect Plots

Legend is an essential component of a Matplotlib axis, used to identify and differentiate various elements within a plot.

A legend is generated by ax.legend() or plt.legend() function. This article demonstrates several arguments for these functions that allow precise control over the legend's appearance.

Legend Location: loc

Use legend(loc=) to specify the location of the legend. Can be either accurate coordinates or string. For example: ax.legend(loc=(0, 0.5)) or ax.legend("upper left").

fig, axes = plt.subplots(1, 3, figsize=(8, 3))
for i, ax in enumerate(axes):
    ax.set_ylim(-2, 1.1)
    for y in ys:
        axes[i].plot(x, y)
    axes[i].legend([f"i={i}" for i in range(5)], loc=(i/3, i/3))
plt.tight_layout()

Number of Columns: ncol

fig, axes = plt.subplots(1, 3, figsize=(8, 3))
for i, ax in enumerate(axes):
    ax.set_ylim(-2, 1.1)
    for y in ys:
        axes[i].plot(x, y)
    axes[i].legend([f"i={i}" for i in range(5)], loc=(0, 0), ncol=i+1)
plt.tight_layout()

Column Spacing: columnspacing

fig, axes = plt.subplots(1, 3, figsize=(8, 3))
for i, ax in enumerate(axes):
    ax.set_ylim(-2, 1.1)
    for y in ys:
        axes[i].plot(x, y)
    axes[i].legend([f"i={i}" for i in range(5)], loc=(0, 0), ncol=2, columnspacing=2*i)
plt.tight_layout()

Handle Length: handlelength

fig, axes = plt.subplots(1, 3, figsize=(8, 3))
for i, ax in enumerate(axes):
    ax.set_ylim(-2, 1.1)
    for y in ys:
        axes[i].plot(x, y)
    axes[i].legend([f"i={i}" for i in range(5)], loc=(0, 0), ncol=2, handlelength=i+1)
plt.tight_layout()

Space Between Handle and Text: handletextpad

fig, axes = plt.subplots(1, 3, figsize=(8, 3))
for i, ax in enumerate(axes):
    ax.set_ylim(-2, 1.1)
    for y in ys:
        axes[i].plot(x, y)
    axes[i].legend([f"i={i}" for i in range(5)], loc=(0, 0), ncol=2, handletextpad=i)
plt.tight_layout()