Drawing flag
- Library: Auxiliary do some of the operations, reduce duplication of work, reduce the amount of code and complexity. Good encapsulation of various operations, without making the wheel is repeated.
- turtle graphics library
- django flask tornado backstage production site
- pandas numpy data analysis
- scipy Scientific Computing
- pygame making games
- tensorflow pytorch keras Artificial Intelligence
- pyspark pyhive Big Data
- pymysql database
- Compared with other Python programming language, variable type is the same. (Represented by three multi-line character string in quotation marks)
- list files (data changes frequently, the reading speed is relatively slow)
- dict dictionary (key-value pair, the key is a hash key is immutable object)
- tuple tuple (data does not change, there will be a variety of data, such as identification numbers, read data fast)
- set collection
Python logic statements
- if conditional statement
- Nested statements
- for loop
function
- def represents a function
Image Processing
- Single Channel: Black and white / gray
- Dual-channel: RGB
The practical operation to use a simple graphics library Python library --turtle
some common methods
- pensize set the brush thickness (adjusted parameter)
- pencolor pen color set (adjusted parameter)
- forward to go forward (100 pixels)
- right turn right from the current position
- left from the current position of the left turn
- speed setting brush speed
- penup down his brush, to end the drawing
Python statements --for loop
for i in range () i is an integer variable from 0
"""
用Python的turtle模块绘制国旗
"""
import turtle
def draw_rectangle(x, y, width, height):
"""绘制矩形"""
turtle.goto(x, y)
turtle.pencolor('red')
turtle.fillcolor('red')
turtle.begin_fill()
for i in range(2):
turtle.forward(width)
turtle.left(90)
turtle.forward(height)
turtle.left(90)
turtle.end_fill()
def draw_star(x, y, radius):
"""绘制五角星"""
turtle.setpos(x, y)
pos1 = turtle.pos()
turtle.circle(-radius, 72)
pos2 = turtle.pos()
turtle.circle(-radius, 72)
pos3 = turtle.pos()
turtle.circle(-radius, 72)
pos4 = turtle.pos()
turtle.circle(-radius, 72)
pos5 = turtle.pos()
turtle.color('yellow', 'yellow')
turtle.begin_fill()
turtle.goto(pos3)
turtle.goto(pos1)
turtle.goto(pos4)
turtle.goto(pos2)
turtle.goto(pos5)
turtle.end_fill()
def main():
"""主程序"""
#设置画笔速度
turtle.speed(12)
# 抬起笔
turtle.penup()
x, y = -270, -180
# 画国旗主体
width, height = 540, 360
draw_rectangle(x, y, width, height)
# 画大星星
pice = 22
center_x, center_y = x + 5 * pice, y + height - pice * 5
turtle.goto(center_x, center_y)
turtle.left(90)
turtle.forward(pice * 3)
turtle.right(90)
draw_star(turtle.xcor(), turtle.ycor(), pice * 3)
x_poses, y_poses = [10, 12, 12, 10], [2, 4, 7, 9]
# 画小星星
for x_pos, y_pos in zip(x_poses, y_poses):
turtle.goto(x + x_pos * pice, y + height - y_pos * pice)
turtle.left(turtle.towards(center_x, center_y) - turtle.heading())
turtle.forward(pice)
turtle.right(90)
draw_star(turtle.xcor(), turtle.ycor(), pice)
# 隐藏海龟
turtle.ht()
# 显示绘图窗口
turtle.mainloop()
main()