[robertoffmoura]

mpl_to_plotly can't convert 3D plots. Matplotlib's Axes3D sets get_frame_on = None, so reading the axes properties raises TypeError: 'NoneType' object is not callable for any figure with a 3D axes, and nothing is converted.

Fix: 3D axes are now converted to plotly scenes:

• each 3D axes becomes a scene (scene, scene2, ...) placed at the position of the axes
• ax.plot lines become scatter3d traces with their color, width, dash style and markers; marker symbols scatter3d lacks (triangles, stars) export as circles, and unlabeled lines stay out of the legend
• scene axes carry the axis limits, labels with their font size and color, log scales, line and tick label colors, and pane colors (blended over the background when translucent), and are hidden when the axis is turned off
• the camera follows view_init (elevation, azimuth and roll), and the box aspect sets the scene aspect ratio
• subplot titles are centered on their scenes
• 3D artists without a scene conversion (scatter, surface, bar, text) warn and are skipped

Before: TypeError: 'NoneType' object is not callable.
After: 3D lines render as scatter3d traces in a plotly scene.

Snippet to reproduce:

import matplotlib

matplotlib.use("Agg")
import matplotlib.pyplot as plt
import numpy as np
import plotly.tools as tls

t = np.linspace(0, 10, 200)


def spiral(fig):
    ax = fig.add_subplot(projection="3d")
    ax.plot(t, np.sin(t), np.cos(t), "r--")
    ax.set_xlabel("x")
    ax.set_ylabel("y")
    ax.set_zlabel("z")


def view_angles(fig):
    ax = fig.add_subplot(projection="3d")
    ax.plot(np.cos(t), np.sin(t), t)
    ax.view_init(elev=15, azim=40)


cases = {
    "spiral": spiral,
    "view_angles": view_angles,
}

for name, build in cases.items():
    fig = plt.figure()
    build(fig)
    fig.savefig(f"{name}_mpl.png")

    p = tls.mpl_to_plotly(fig)  # TypeError before this change
    p.write_image(f"{name}_plotly.png")

matplotlib	plotly before	plotly after
	- TypeError: 'NoneType' object is not callable
	- TypeError: 'NoneType' object is not callable

[camdecoster]

Thanks for putting this together! I've added it to my review list.