python matplotlib mistake notes

I am trying to use Python to draw a fig with some data.

Get some weird error.


I am using pandas and matplotlib to deal with data.

1 )   But when I was trying to change the direction of the lable of x axis. It didn't change.

I searched online. Someone says, if use "plt.twinx()", the "plt.xticks(rotation=90)" will be not working.

In fact, that still works, the rotation function has to be put before the generate twinx.


2 )  Generate picture with blank

The figure setting has to be placed at the begining before plot any data. Otherwise, this function will clear all data and show a blank picture at the end.

The "figsize" unit is inch. 

plt.plot(x, y1,label = "sh", color='red')
plt.plot(x, y2,label = "hgt", color='blue')
plt.plot(x, y3,label = "cumsum", color='black')
plt.savefig("filename.png",dpi=500,bbox_inches = 'tight')