4 examples of 'matplotlib axis equal' in Python

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def set_axes_equal(ax):
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    '''Make axes of 3D plot have equal scale so that spheres appear as spheres,
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    cubes as cubes, etc..  This is one possible solution to Matplotlib's
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    ax.set_aspect('equal') and ax.axis('equal') not working for 3D.
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    Input
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      ax: a matplotlib axis, e.g., as output from plt.gca().
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    '''
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    x_limits = ax.get_xlim3d()
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    y_limits = ax.get_ylim3d()
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    z_limits = ax.get_zlim3d()
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    x_range = abs(x_limits[1] - x_limits[0])
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    x_middle = np.mean(x_limits)
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    y_range = abs(y_limits[1] - y_limits[0])
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    y_middle = np.mean(y_limits)
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    z_range = abs(z_limits[1] - z_limits[0])
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    z_middle = np.mean(z_limits)
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    # The plot bounding box is a sphere in the sense of the infinity
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    # norm, hence I call half the max range the plot radius.
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    plot_radius = 0.5*max([x_range, y_range, z_range])
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    ax.set_xlim3d([x_middle - plot_radius, x_middle + plot_radius])
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    ax.set_ylim3d([y_middle - plot_radius, y_middle + plot_radius])
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    ax.set_zlim3d([z_middle - plot_radius, z_middle + plot_radius])

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def square_axis(axes=None):
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  """
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  Expands the x- and y-limits on the given axes so that they are equal
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  (defaults to the current axes).
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  """
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  if axes is None:
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    axes = gca()
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  tmpv = axes.axis()
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  xmax = max([tmpv[1], tmpv[3]])
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  xmin = min([tmpv[0], tmpv[2]])
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  axes.axis([xmin, xmax, xmin, xmax])

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@staticmethod
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def set_axes_equal(ax):
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    """ Sets equal aspect ratio across the three axes of a 3D plot.
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    Contributed by Xuefeng Zhao.
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    :param ax: a Matplotlib axis, e.g., as output from plt.gca().
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    """
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    bounds = [ax.get_xlim3d(), ax.get_ylim3d(), ax.get_zlim3d()]
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    ranges = [abs(bound[1] - bound[0]) for bound in bounds]
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    centers = [np.mean(bound) for bound in bounds]
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    radius = 0.5 * max(ranges)
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    lower_limits = centers - radius
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    upper_limits = centers + radius
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    ax.set_xlim3d([lower_limits[0], upper_limits[0]])
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    ax.set_ylim3d([lower_limits[1], upper_limits[1]])
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    ax.set_zlim3d([lower_limits[2], upper_limits[2]])

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def setup_axis(X, Y, ax=None, fig=None, ylims=None):
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    """Setup axis, including timer for animation or snaps
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    Parameters
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    ----------
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    X :
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        space disctretization to get limits
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    Y :
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        solution to get limits
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    ax :
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        ax where to put everything, if None current axes are used (Default value = None)
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    fig :
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        fig where to put everything, if None current figure is used (Default value = None)
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    ylims :
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        custom ylims, if None y axis limits are calculated from Y (Default value = None)
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    Returns
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    -------
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    ax
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    fig
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    time_text
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        object to fill in text
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    """
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    if ax is None:
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        fig = plt.gcf()
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        ax = plt.gca()
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    if ylims is None:
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        lowery = nm.min(Y) - nm.min(Y) / 10
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        uppery = nm.max(Y) + nm.max(Y) / 10
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    else:
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        lowery = ylims[0]
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        uppery = ylims[1]
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    ax.set_ylim(lowery, uppery)
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    ax.set_xlim(X[0], X[-1])
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    time_text = ax.text(X[0] + nm.sign(X[0]) * X[0] / 10,
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                        uppery - uppery / 10,
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                        'empty', fontsize=15)
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    return ax, fig, time_text