参考:
官方教程:
http://matplotlib.org/1.3.1/users/recipes.html
http://stackoverflow.com/questions/13515471/matplotlib-how-to-prevent-x-axis-labels-from-overlapping-each-other
# Tell matplotlib to interpret the x-axis values as dates
ax.xaxis_date()
# Make space for and rotate the x-axis tick labels
fig.autofmt_xdate()
这两句很重要,可以不再看到叠在一起的字符串
格式化时间字符串
http://stackoverflow.com/questions/3486121/how-to-plot-data-against-specific-dates-on-the-x-axis-using-matplotlib
下面这个链接是说如何旋转x轴的字符
http://stackoverflow.com/questions/10998621/rotate-axis-text-in-python-matplotlib
其他的一些参考
http://stackoverflow.com/questions/10279778/matplotlib-centered-bar-chart-with-dates