Fix font display for Matplotlib

Matplotlib-font.py

# Method 1
# 須先下載wqy-microhei.ttc，因中文顯示需做特殊處理
zhfont = matplotlib.font_manager.FontProperties(fname='/Users/youngmihuang/Downloads/wqy-microhei.ttc')

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# Method 2

# install Korean font
!apt install fonts-nanum

import matplotlib.pyplot as plt
import matplotlib.font_manager as fm

# set the font and rebuild font manager
plt.rc('font', family='NanumBarunGothic') 
fm._rebuild()

# set high resolution to show the font clearly
%config InlineBackend.figure_format = 'retina'

# After executing this cell, 
# you need to click "Restart runtime..."(Cmd/Ctrl+M .)
# and then execute this cell again.