raspberry-pi - 用python Linux（无GUI）中生成统计图

我有这样一个需求：在我的raspberry pi 3中运行着一个爬虫程序，根据爬到的数据，使用matplotlib自动生成统计图（图片格式），然后发送到我的邮箱.

但是我ssh远程登录树莓派，运行如下脚本生成test.png图片时

import matplotlib.pyplot as plt
import numpy as np
import matplotlib

t = np.arange(0.0, 10.0, 0.001)
s = np.sin(2*np.pi*t)
plt.plot(t, s)

plt.xlabel('time (s)')
plt.ylabel('voltage (mV)')
plt.title('About as simple as it gets, folks')
plt.grid(True)
plt.savefig("test.png")

出现如下错误：

(process:2818): Gtk-WARNING **: Locale not supported by C library.
           Using the fallback 'C' locale.
Unable to init server: Could not connect: Connection refused
Unable to init server: Could not connect: Connection refused

(simple_plot.py:2818): Gdk-CRITICAL **: gdk_cursor_new_for_display: assertion 'GDK_IS_DISPLAY (display)' failed
Traceback (most recent call last):
  File "simple_plot.py", line 1, in 
    import matplotlib.pyplot as plt
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 114, in 
    _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/backends/__init__.py", line 32, in pylab_setup
    globals(),locals(),[backend_name],0)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/backends/backend_gtk3agg.py", line 11, in 
    from . import backend_gtk3
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/backends/backend_gtk3.py", line 58, in 
    cursors.MOVE          : Gdk.Cursor.new(Gdk.CursorType.FLEUR),
TypeError: constructor returned NULL

而我在树莓派gui系统中运行上述脚本是可以生成test.png文件的。
所以上述错误只是出现在无gui的情况下，google了多个结果都没有解决方法。

1. 使用python绘制统计图库（类似matplotlib)可以在无gui的情况下根据所给数据生成统计图（png,jpeg等等)。

2. 或者有别的方法实现我上述需求。