matplotlib

very good tutorial
matplotlib和PIL打开图片的方法

command

0. figure

• size

  plt.figure(figsize=(20,10)) # this command shall be at beginning.
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Based on ref matplotlib.pyplot.figure, the default size of a plot is 6.4 and 4.8.
rcParams["figure.figsize"] = [6.4, 4.8]

• subplots size
  fig, ax1 = plt.subplots(figsize=(20, 10))
  如果不用上面的命令，而用ax.figure.set_size_inches(50,10)，不好使。

• other thins
  plt.figure(dpi=80, facecolor='w', edgecolor='w')

1. line
   plt.plot(X, C, color="blue", linewidth=1.0, linestyle="-", label="balala data", marker='tri', markersize=3,)

2. limit (range)
   plt.xlim(-4.0,4.0)

3. legend
   plt.legend(loc='upper left')

4. ticks
   plt.xticks(np.linspace(-4,4,9,endpoint=True))

5. label of axis
   plt.xlabel("This is X axis")

6. point style
   For style of point, see ^[1] and ^[2]

7. save/load

   • save
     plt.savefig("name.png") Note that plt.show() will clean the content, so savefig should be in front
   • load

   img = mpimg.imread("3732video_star_distri.png")
   plt.imshow(img)

8. histogram
   plt.hist(mydict.values(), bins=10)

9. add additional ticks

   lines = plt.plot(x,y)
   
   ax = lines[0].axes
   lim = ax.get_ylim()
   ax.set_yticks(list(ax.get_yticks()) + extraticks_list)
   ax.set_ylim(lim)

ref: adding extra axis ticks using matplotlib

10. arrow
    plt.arrow(datetime(2018,4,21), 1.268, 30, 0, linestyle=(0,(5,10)))
    注意：是(x,y,dx,dy)，第三个和第四个参数是箭头的长度；这里30被当做30天；(offset,(onoffseq))格式的参考可见：linestyle

11. add x2 axis
    ax2 = ax1.twinx()
    ref: example code

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concept

• axes
  Figure > axes
  ref: What is ‘axes’(NOTE: not ‘axis’)
• plot vs. subplot vs. figure.add_subplot()
  ref: What is the difference between drawing plots using plot, axes or figure in matplotlib?

global setting

mpl.rcParams['xtick.labelsize'] = 24
mpl.rcParams['ytick.labelsize'] = 24

• font

  font = {'family' : 'normal',
          'weight' : 'bold',
          'size'   : 22}
  
  matplotlib.rc('font', **font)

ref:

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1. matplotlib.pyplot.plo ↩

2. marker example ↩