Matplotlib 后端 GTK3 Agg 使用开罗？

Question

I don't understand why while I' trying to use the Gtk3Agg backend and I end up with an error telling me the cairo module is not found.

** (simple_plot_in_gtk3.py:312517): WARNING **: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
    Traceback (most recent call last):
      File "simple_plot_in_gtk3.py", line 5, in 
        from matplotlib.backends.backend_gtk3agg import FigureCanvasGTK3Agg as FigureCanvas
      File "/Produits/publics/x86_64.Linux.RH6/python/3.4.1/lib/python3.4/site-packages/matplotlib-1.3.1-py3.4-linux-x86_64.egg/matplotlib/backends/backend_gtk3agg.py", line 1, in 
        import cairo
    ImportError: No module named 'cairo'

I'm trying to run the matplotlib/GTK3 example from matplolib site.

Answer 1

If you look at the backend_gtk3agg.py file, you'll see that the first lines in the file are;

import cairo
import numpy as np
import sys
import warnings

import backend_agg
import backend_gtk3
from matplotlib.figure import Figure
from matplotlib import transforms

So, yes, the gtk3agg backend requires the cairo library and its Python bindings . And numpy.

It uses Cairo for ImageSurface buffers, because that is something AGG does not provide . I do not know why the gtk3agg developers chose this method. Presumably because it was convenient.

Answer 2

为 Python安装Python binging工作：

$ pip install pycairo