Text Rotation Mode

This example illustrates the effect of rotation_mode on the positioning of rotated text.

Rotated Texts are created by passing the parameter rotation to the constructor or the axes' method text.

The actual positioning depends on the additional parameters horizontalalignment, verticalalignment and rotation_mode. rotation_mode determines the order of rotation and alignment:

• rotation_mode='default' (or None) first rotates the text and then aligns the bounding box of the rotated text.

• rotation_mode='anchor' aligns the unrotated text and then rotates the text around the point of alignment.

import matplotlib.pyplot as plt
import numpy as np


def test_rotation_mode(fig, mode, subplot_location):
    ha_list = ["left", "center", "right"]
    va_list = ["top", "center", "baseline", "bottom"]
    axs = np.empty((len(va_list), len(ha_list)), object)
    gs = subplot_location.subgridspec(*axs.shape, hspace=0, wspace=0)
    axs[0, 0] = fig.add_subplot(gs[0, 0])
    for i in range(len(va_list)):
        for j in range(len(ha_list)):
            if (i, j) == (0, 0):
                continue  # Already set.
            axs[i, j] = fig.add_subplot(
                gs[i, j], sharex=axs[0, 0], sharey=axs[0, 0])
    for ax in axs.flat:
        ax.set(aspect=1)

    # labels and title
    for ha, ax in zip(ha_list, axs[-1, :]):
        ax.set_xlabel(ha)
    for va, ax in zip(va_list, axs[:, 0]):
        ax.set_ylabel(va)
    axs[0, 1].set_title(f"rotation_mode='{mode}'", size="large")

    kw = (
        {} if mode == "default" else
        {"bbox": dict(boxstyle="square,pad=0.", ec="none", fc="C1", alpha=0.3)}
    )

    # use a different text alignment in each axes
    for i, va in enumerate(va_list):
        for j, ha in enumerate(ha_list):
            ax = axs[i, j]
            # prepare axes layout
            ax.set(xticks=[], yticks=[])
            ax.axvline(0.5, color="skyblue", zorder=0)
            ax.axhline(0.5, color="skyblue", zorder=0)
            ax.plot(0.5, 0.5, color="C0", marker="o", zorder=1)
            # add text with rotation and alignment settings
            tx = ax.text(0.5, 0.5, "Tpg",
                         size="x-large", rotation=40,
                         horizontalalignment=ha, verticalalignment=va,
                         rotation_mode=mode, **kw)

    if mode == "default":
        # highlight bbox
        fig.canvas.draw()
        for ax in axs.flat:
            text, = ax.texts
            bb = text.get_window_extent().transformed(ax.transData.inverted())
            rect = plt.Rectangle((bb.x0, bb.y0), bb.width, bb.height,
                                 facecolor="C1", alpha=0.3, zorder=2)
            ax.add_patch(rect)


fig = plt.figure(figsize=(8, 5))
gs = fig.add_gridspec(1, 2)
test_rotation_mode(fig, "default", gs[0])
test_rotation_mode(fig, "anchor", gs[1])
plt.show()

References

The use of the following functions, methods, classes and modules is shown in this example:

• matplotlib.axes.Axes.text / matplotlib.pyplot.text