python学习实例(1)
【摘要】 #======================================#1.2 计算机编程的基本概念#====================================== #++++++++++++++++++++++++++++++++++++++#1.2.2 从Python语言进入计算机语言的世界#+++++++++++++++++++++++++++++...
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#======================================
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#1.2 计算机编程的基本概念
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#======================================
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#++++++++++++++++++++++++++++++++++++++
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#1.2.2 从Python语言进入计算机语言的世界
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#++++++++++++++++++++++++++++++++++++++
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#<程序:例子1>
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def F(x,y):
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return(x*x+y*y)
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print("F(2,2)=",F(2,2))
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print("F(3,2)=",F(3,2))
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#<程序:例子2>
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def Pr():
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for i in range(0,10): # 索引 i = 0 to 9
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print("Hello world")
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#在函数程序外面Pr()
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Pr()
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# 输出 Hello world 10 遍
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#<程序:布尔类型例子>
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b = 100<101
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print(b)
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#<程序:for循环例子>
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for i in range(1, 5):
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print(i)
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#<程序:while循环例子>
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i = 1
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while i<5:
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print(i)
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i=i+1
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#<程序:if语句例子>
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i=10
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j=11
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if i< j:
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print("i<j")
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else:
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print("i>=j")
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#======================================
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#1.3 计算机核心知识——算法(Algorithm)
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#======================================
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#++++++++++++++++++++++++++++++++++++++
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#1.3.2 解平方根算法一
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#++++++++++++++++++++++++++++++++++++++
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#<程序:平方根运算1>
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def square_root_1(): #函数定义,函数名为square_root_1
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c = 10 #所求平方根的输入,即该段程序求根号10
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i = 0 #记录执行循环次数
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g = 0
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for j in range(0,c+1): #for 循环开始
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if (j * j > c and g==0):#if 语句块,获取g,使得g2<c,(g+1)2>c
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g = j - 1
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#for 循环结束
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while (abs(g * g - c) > 0.0001):#判断g2-c是否在精度范围内,while循环
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g += 0.00001 #g每次加步长,以逼近所求解
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i = i+1
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print ("%d:g = %.5f" % (i,g))
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#函数外,执行下面的语句
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square_root_1()
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#++++++++++++++++++++++++++++++++++++++
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#1.3.3 解平方根算法二
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#++++++++++++++++++++++++++++++++++++++
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#<程序:平方根运算2-二分法>
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def square_root_2():
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i = 0
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c = 10
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m_max = c
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m_min = 0
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g = (m_min+m_max)/2
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while (abs(g*g -c) > 0.00000000001): #while循环开始
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if (g*g <c):
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m_min = g
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else:
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m_max = g
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g = (m_min + m_max)/2
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i = i+1
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print ("%d:%.13f" % (i,g)) #while循环结束
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#函数之外执行
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square_root_2 ()
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#++++++++++++++++++++++++++++++++++++++
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#1.3.4 解平方根算法三
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#++++++++++++++++++++++++++++++++++++++
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#<程序:平方根运算3-牛顿法>
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def square_root_3():
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c = 10
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g = c/2
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i = 0
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while abs(g*g - c) > 0.00000000001:
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g = (g + c/g)/2
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i = i+1
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print("%d:%.13f" % (i,g))
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square_root_3()
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#======================================
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#1.5 计算机前沿知识——大数据(Big Data)
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#======================================
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#++++++++++++++++++++++++++++++++++++++
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#1.5.5 对数据和逻辑的正确态度
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#++++++++++++++++++++++++++++++++++++++
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#<程序:求圆周率-蒙地卡罗法>
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import random
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def pi(times):
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sum=0
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for i in range(times):
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x=random.random()
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y=random.random()
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d2=x*x+y*y #算到原点的距离
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if d2<=1: sum+=1 #距离<=1, 代表在圆里面。
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return(sum/times*4)
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#函数外执行
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times=100000000
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x=pi(times)
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print("pi=%.8f"%(x))
文章来源: fantianzuo.blog.csdn.net,作者:兔老大RabbitMQ,版权归原作者所有,如需转载,请联系作者。
原文链接:fantianzuo.blog.csdn.net/article/details/83025169
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