basic

static-method

python 中并没有像是 Java 里的 static 关键字,取代的是 @classmethod 和 @staticmethod

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class A:

    name = 'A'

    # 至少有一个隐式形参 (本类 cls 对象), 可以访问类属性
    @classmethod
    def a(cls):
        print(cls.name)

    # 无形参, 也就是说拿不到类属性
    @staticmethod
    def b():
        print('b')


A.a()
A.b()
A
b

multi-condition

if(a||b)当 a 为真时，还会对 b 求值吗?

不会

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import time


def calculate(name, t):
    print("calculating: ", name, "seconds needs: ", t)
    time.sleep(t)
    return True


if (calculate('A', 2) or calculate('B', 2)):
    print("Done")

calculating:  A seconds needs:  2
Done

modules

base64

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import base64

username = 'Weidows'
password = '123456'

encode = base64.b64encode((username + ":" + password).encode())
# Basic V2VpZG93czoxMjM0NTY==
headers = {"Authorization": "Basic " + encode.decode()}

print(headers)
{'Authorization': 'Basic V2VpZG93czoxMjM0NTY='}

多线程-进程

Python 多线程不能利用 CPU 多核优势，IO 密集型可用多线程，CPU 密集型适合用多进程 [2]

也就是说只有 IO 密集型任务适用多线程,其他情况: 多进程 > 不用 > 多线程, API 区别如下:[3]

R9zQZh.png

虽然但是,很多情况下涉及到资源共享, 多进程处理起来比较麻烦,还是多线程舒服.

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from concurrent.futures import ThreadPoolExecutor
import threading
import multiprocessing
import time

multi_num = multiprocessing.cpu_count() * 2

def counter(num):
    time.sleep(num)
    print(threading.currentThread().name, num, end='\t')


if __name__ == '__main__':
    with ThreadPoolExecutor(max_workers=multi_num) as thread_pool:
        start = time.time()
        thread_pool.map(counter, range(10))

        # 等待任务执行完再跳回 main
        thread_pool.shutdown(wait=True)
        print("多线程: ", time.time() - start)
ThreadPoolExecutor-0_0 0	ThreadPoolExecutor-0_1 1	ThreadPoolExecutor-0_0 2	ThreadPoolExecutor-0_2 3	ThreadPoolExecutor-0_3 4	ThreadPoolExecutor-0_4 5	ThreadPoolExecutor-0_5 6	ThreadPoolExecutor-0_6 7	ThreadPoolExecutor-0_7 8	ThreadPoolExecutor-0_8 9	多线程:  9.009207010269165

opengl

彩色三角形

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# -------------------------------------------
# quidam_01.py 三维空间的世界坐标系和三角形
# -------------------------------------------

from OpenGL.GL import *
from OpenGL.GLUT import *


def draw():
    # ---------------------------------------------------------------
    glBegin(GL_LINES)  # 开始绘制线段（世界坐标系）

    # 以红色绘制x轴
    glColor4f(1.0, 0.0, 0.0, 1.0)  # 设置当前颜色为红色不透明
    glVertex3f(-0.8, 0.0, 0.0)  # 设置x轴顶点（x轴负方向）
    glVertex3f(0.8, 0.0, 0.0)  # 设置x轴顶点（x轴正方向）

    # 以绿色绘制y轴
    glColor4f(0.0, 1.0, 0.0, 1.0)  # 设置当前颜色为绿色不透明
    glVertex3f(0.0, -0.8, 0.0)  # 设置y轴顶点（y轴负方向）
    glVertex3f(0.0, 0.8, 0.0)  # 设置y轴顶点（y轴正方向）

    # 以蓝色绘制z轴
    glColor4f(0.0, 0.0, 1.0, 1.0)  # 设置当前颜色为蓝色不透明
    glVertex3f(0.0, 0.0, -0.8)  # 设置z轴顶点（z轴负方向）
    glVertex3f(0.0, 0.0, 0.8)  # 设置z轴顶点（z轴正方向）

    glEnd()  # 结束绘制线段

    # ---------------------------------------------------------------
    glBegin(GL_TRIANGLES)  # 开始绘制三角形（z轴负半区）

    glColor4f(1.0, 0.0, 0.0, 1.0)  # 设置当前颜色为红色不透明
    glVertex3f(-0.5, -0.366, -0.5)  # 设置三角形顶点
    glColor4f(0.0, 1.0, 0.0, 1.0)  # 设置当前颜色为绿色不透明
    glVertex3f(0.5, -0.366, -0.5)  # 设置三角形顶点
    glColor4f(0.0, 0.0, 1.0, 1.0)  # 设置当前颜色为蓝色不透明
    glVertex3f(0.0, 0.5, -0.5)  # 设置三角形顶点

    glEnd()  # 结束绘制三角形

    # ---------------------------------------------------------------
    glFlush()  # 清空缓冲区，将指令送往硬件立即执行


if __name__ == "__main__":
    glutInit()  # 1. 初始化glut库
    glutCreateWindow('Quidam Of OpenGL')  # 2. 创建glut窗口
    glutDisplayFunc(draw)  # 3. 注册回调函数draw()
    glutMainLoop()  # 4. 进入glut主循环

点线抛物线

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from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from numpy import *
import sys


def init():
    glClearColor(1.0, 1.0, 1.0, 1.0)
    gluOrtho2D(-5.0, 5.0, -5.0, 5.0)


def plotfunc():
    glClear(GL_COLOR_BUFFER_BIT)
    glColor3f(1.0, 0.2, 0.6)
    glPointSize(3.0)

    glBegin(GL_POINTS)
    for x in arange(-5.0, 5.0, 0.1):  #from -5.0 to 5.0 plus 0.1 every time
        y = x * x
        glVertex2f(x, y)
    glEnd()
    glFlush()


def main():
    glutInit(sys.argv)
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB)
    glutInitWindowPosition(50, 100)
    glutInitWindowSize(400, 400)
    glutCreateWindow("Function Plotter")
    glutDisplayFunc(plotfunc)

    init()
    glutMainLoop()


main()

转动时钟

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from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
import math
import time

h = 0
m = 0
s = 0


def Draw():
    PI = 3.1415926
    R = 0.5
    TR = R - 0.05
    glClear(GL_COLOR_BUFFER_BIT)
    glLineWidth(5)
    glBegin(GL_LINE_LOOP)
    for i in range(100):
        glVertex2f(R * math.cos(2 * PI / 100 * i),
                   R * math.sin(2 * PI / 100 * i))
    glEnd()
    glLineWidth(2)
    for i in range(100):
        glBegin(GL_LINES)
        glVertex2f(TR * math.sin(2 * PI / 12 * i),
                   TR * math.cos(2 * PI / 12 * i))
        glVertex2f(R * math.sin(2 * PI / 12 * i),
                   R * math.cos(2 * PI / 12 * i))
        glEnd()
    glLineWidth(1)

    h_Length = 0.2
    m_Length = 0.3
    s_Length = 0.4
    count = 60.0
    s_Angle = s / count
    count *= 60
    m_Angle = (m * 60 + s) / count
    count *= 12
    h_Angle = (h * 60 * 60 + m * 60 + s) / count
    glLineWidth(1)
    glBegin(GL_LINES)
    glVertex2f(0.0, 0.0)
    glVertex2f(s_Length * math.sin(2 * PI * s_Angle),
               s_Length * math.cos(2 * PI * s_Angle))
    glEnd()
    glLineWidth(5)
    glBegin(GL_LINES)
    glVertex2f(0.0, 0.0)
    glVertex2f(h_Length * math.sin(2 * PI * h_Angle),
               h_Length * math.cos(2 * PI * h_Angle))
    glEnd()
    glLineWidth(3)
    glBegin(GL_LINES)
    glVertex2f(0.0, 0.0)
    glVertex2f(m_Length * math.sin(2 * PI * m_Angle),
               m_Length * math.cos(2 * PI * m_Angle))
    glEnd()
    glLineWidth(1)
    glBegin(GL_POLYGON)
    for i in range(100):
        glVertex2f(0.03 * math.cos(2 * PI / 100 * i),
                   0.03 * math.sin(2 * PI / 100 * i))
    glEnd()
    glFlush()


def Update():
    global h, m, s
    t = time.localtime(time.time())
    h = int(time.strftime('%H', t))
    m = int(time.strftime('%M', t))
    s = int(time.strftime('%S', t))
    glutPostRedisplay()


glutInit()
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA)
glutInitWindowSize(400, 400)
glutCreateWindow("My clock")
glutDisplayFunc(Draw)
glutIdleFunc(Update)
glutMainLoop()

Hello-World-pyglet

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import pyglet

window = pyglet.window.Window()

label = pyglet.text.Label('Hello, world',
                          font_name='Times New Roman',
                          font_size=36,
                          x=window.width // 2,
                          y=window.height // 2,
                          anchor_x='center',
                          anchor_y='center')


@window.event
def on_draw():
    window.clear()
    label.draw()


pyglet.app.run()

茶壶

动态

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from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *


def drawFunc():
    #清楚之前画面
    glClear(GL_COLOR_BUFFER_BIT)
    glRotatef(0.1, 5, 5, 0)  #(角度,x,y,z)
    glutWireTeapot(0.5)
    #刷新显示
    glFlush()


#使用glut初始化OpenGL
glutInit()
#显示模式:GLUT_SINGLE无缓冲直接显示|GLUT_RGBA采用RGB(A非alpha)
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA)
#窗口位置及大小-生成
glutInitWindowPosition(0, 0)
glutInitWindowSize(400, 400)
glutCreateWindow(b"first")
#调用函数绘制图像
glutDisplayFunc(drawFunc)
glutIdleFunc(drawFunc)
#主循环
glutMainLoop()

静态

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from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *


def drawFunc():
    glClear(GL_COLOR_BUFFER_BIT)
    # 设置为红色
    glColor3f(1.0, 0.0, 0.0)
    glutWireTeapot(0.5)
    glFlush()


glutInit()
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA)
glutInitWindowSize(400, 400)

#参数为b类型而不是string
glutCreateWindow(b"Teapot")
glutDisplayFunc(drawFunc)
glutMainLoop()

数据分析

numpy

newaxis

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import numpy as np

A = np.array([[2, 0, 2, 1], [2, 0, 2, 2]])

print(A)
print("A.shape: ", A.shape)

# new 一个一维数组,然后把 A 整个怼进去
B = A[np.newaxis, :]
print(B)
print("B.shape: ", B.shape)

C = A[:, np.newaxis]
print(C)
print("C.shape: ", C.shape)

# 把每个第二维第四位的元素怼进一个新数组,把原第二位替换为此新数组
D = A[:, np.newaxis, 3]
print(D)
print("D.shape: ", D.shape)

[[2 0 2 1]
 [2 0 2 2]]
A.shape:  (2, 4)
[[[2 0 2 1]
  [2 0 2 2]]]
B.shape:  (1, 2, 4)
[[[2 0 2 1]]

 [[2 0 2 2]]]
C.shape:  (2, 1, 4)
[[1]
 [2]]
D.shape:  (2, 1)

分割线

借物表

[1]: How does numpy.newaxis work and when to use it?

[2]: Python threadpool与multiprocessing

[3]: Python并发实战，怎样使用多进程multiprocessing加速程序运行