【lesson1】sin、cosを描く

import math

import matplotlib.pyplot as plt

import numpy as np

PI = math.radians(180) # Define PI

a = np.linspace(0, PI*2, int(PI*2/0.1))

b = []

c = []

for i in a:

b.append(math.cos(i))

c.append(math.sin(i))

plt.plot(c)

plt.plot(b)

plt.show()

matplotlibをimportする時、import matplotlib.pyplot as pltを使うと、下記のエラーメッセージが出てくる

File "e1.py", line 3, in
    import matplotlib.pyplot as plt
  File "/home/lhw/.local/lib/python3.6/site-packages/matplotlib/pyplot.py", line 2371, in
    switch_backend(rcParams["backend"])
  File "/home/lhw/.local/lib/python3.6/site-packages/matplotlib/pyplot.py", line 207, in switch_backend
    backend_mod = importlib.import_module(backend_name)
  File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/home/lhw/.local/lib/python3.6/site-packages/matplotlib/backends/backend_tkagg.py", line 1, in
    from . import _backend_tk
  File "/home/lhw/.local/lib/python3.6/site-packages/matplotlib/backends/_backend_tk.py", line 5, in
    import tkinter as Tk
ModuleNotFoundError: No module named 'tkinter'

tkinterをインストールすれば解決できる。

sudo apt-get install python3-tk

matplotlibの使い方：
※https://matplotlib.org/users/interactive.html