ricky10116r2d2的部落格

Python_Matplotlib - 1. Join styles

https://matplotlib.org/gallery/api/joinstyle.html#sphx-glr-gallery-api-joinstyle-py

====== 程式碼 + 註解 ==========

# https://matplotlib.org/gallery/api/joinstyle.html#sphx-glr-gallery-api-joinstyle-py

"""
===========
Join styles
===========

Illustrate the three different join styles.
"""

import numpy as np
import matplotlib.pyplot as plt

def plot_angle(ax, x, y, angle, style):                   #  定義一個畫圖的 def
    phi = np.radians(angle)                               #  np.radians(180) = 3.14159265
                                                          #  np.radians(8) =  0.139626340
    xx = [x + .5, x, x + .5*np.cos(phi)]      # x = 0 y =0 ==> xx =[0.5,0,0+0.5*cos(phi)]
    yy = [y, y, y + .5*np.sin(phi)]           # yy = 圖形 3 點 Y座標位置
   
    ax.plot(xx, yy, lw=8, color='blue', solid_joinstyle=style)   
    ax.plot(xx[1:], yy[1:], lw=1, color='orange')                   # 後 2 點
    #ax.plot(xx[1::-1], yy[1::-1], lw=1, color='black')            # 前 2 點
    ax.plot(xx[:2], yy[:2], lw=1, color='black')                   # 前 2 點
    ax.plot(xx[1:2], yy[1:2], 'o', color='red', markersize=3)     # 紅點 3點裡面的第2點
    ax.text(x, y + .2, '%.0f degrees' % angle)

fig, ax = plt.subplots()      # fig, ax = plt.subplots() =>   fig = plt.figure()  +  ax = fig.add_subplot(111)
ax.set_title('Join style')

for x, style in enumerate((('miter', 'round', 'bevel'))):
    ax.text(x, 5, style)                                  # x 依順序 => 0 1 2 , style 依順序 => 'miter', 'round', 'bevel'
    for i in range(5):
        plot_angle(ax, x, i, pow(2.0, 3 + i), style)     # 調用 plot_angle  i 依順序 => 0 1 2 3 4  pow : 函数是计算x的y次方
                                                         # loop = 1 時 x = 0  i = 0  angle = 2^3 = 8
                                                         # loop = 2 時 x = 0  i = 1  angle = 2^4 = 16
                                                         # loop = 2 時 x = 0  i = 2  angle = 2^5 = 32
ax.set_xlim(-.5, 2.75)
ax.set_ylim(-.5, 5.5)    # 設定:界線
plt.show()

# https://stackoverflow.com/questions/34162443/why-do-many-examples-use-fig-ax-plt-subplots-in-matplotlib-pyplot-python

================

xx 和 yy 的 3 點