python_day02_练习

选择

布尔类型、数值和表达式

• 注意：比较运算符的相等是两个等号，一个等到代表赋值
• 在Python中可以用整型0来代表False，其他数字来代表True
• 后面还会讲到 is 在判断语句中的用发

 

[[[41.86550961 15.53771491 17.69573087]
  [47.04474791 22.01176278 21.58015959]
  [52.22398621 28.48581066 25.46458832]
  ...
  [95.3843054  93.65789263 63.01406601]
  [95.3843054  93.65789263 63.01406601]
  [94.52109902 92.79468625 61.28765324]]

 [[42.2971128  15.9693181  18.12733406]
  [47.04474791 22.01176278 21.58015959]
  [52.22398621 28.48581066 25.46458832]
  ...
  [95.3843054  93.65789263 63.01406601]
  [95.3843054  93.65789263 63.01406601]
  [94.52109902 92.79468625 61.28765324]]

 [[42.72871599 16.83252448 17.69573087]
  [47.4763511  22.44336598 22.01176278]
  [52.65558941 28.91741385 25.89619151]
  ...
  [95.3843054  93.65789263 63.01406601]
  [95.3843054  93.65789263 63.01406601]
  [94.95270221 93.22628944 62.58246282]]

 ...

 [[65.60368516 67.33009793 56.54001813]
  [71.21452666 73.37254261 63.4456692 ]
  [79.4149873  83.29941603 75.09895538]
  ...
  [28.91741385 15.10611171 24.16977874]
  [29.34901705 15.9693181  23.73817555]
  [29.78062024 18.99054044 28.05420747]]

 [[67.33009793 69.0565107  58.2664309 ]
  [72.94093942 75.09895538 65.60368516]
  [81.14140007 85.02582879 76.82536815]
  ...
  [30.64382662 16.83252448 25.89619151]
  [29.34901705 15.53771491 24.60138194]
  [28.91741385 18.12733406 27.62260428]]

 [[56.54001813 58.2664309  52.22398621]
  [66.03528835 70.78292346 63.87727239]
  [80.27819368 87.61544795 79.4149873 ]
  ...
  [33.66504896 22.87496917 31.07542981]
  [30.64382662 19.85374683 28.91741385]
  [31.50703301 22.01176278 27.62260428]]]

Out[64]:

<matplotlib.image.AxesImage at 0x111f5bcf8>

 

 

EP：

• 产生两个随机整数number1和number2，然后显示给用户，使用户输入数字的和，并判定其是否正确
• 进阶:写一个随机序号点名程序

In [69]:

 

number_1 = random.randrange(0,10)

number_2 = random.randrange(0,10)​

while 1:

    sum_ = eval(input('>>'))

    if sum_ == (number_1 + number_2):

        print('Congratulations! Correct~')

    else:

        print('Sorry~SB.')

 

. . .

if语句

• 如果条件正确就执行一个单向if语句，亦即当条件为真的时候才执行if内部的语句

• Python有很多选择语句:

  • 单向if
  • 双向if-else
  • 嵌套if
  • 多向if-elif-else

• 注意：当语句含有子语句的时候，那么一定至少要有一个缩进，也就是说如果有儿子存在，那么一定要缩进

• 切记不可tab键和space混用，单用tab 或者 space

• 当你输出的结果是无论if是否为真时都需要显示时，语句应该与if对齐

In [72]:

input_  = eval(input('>>'))

if input_ > number:

    print('太大啦')

if input_ < number:

    print('太小啦')

if number == input_:

    print('正好')

print('不要灰心')

>>1
正好
不要灰心

李文浩相亲测试树

  年龄

老 年轻
拜拜
帅 否 是 考虑一下 老婆 没有 有 马上结婚 回家的诱惑

代码写不出来的立马分手,从此社会上有多出一个渣男/渣女.

In [4]:

 

age = input('年轻嘛[y/n]')

if age == 'y':

    handsome = input('帅否[y/n]')

    if handsome == 'y':

        wife = input('有没有老婆[y/n]')

        if wife == 'y':

            print('回家的诱惑')

        else:

            print('立马结婚')

    else:

        print('考虑一下')

else:

    print('拜拜~')

 

年轻嘛[y/n]y
帅否[y/n]y
有没有老婆[y/n]y
回家的诱惑

 

EP：

• 用户输入一个数字，判断其实奇数还是偶数
• 进阶：可以查看下4.5实例研究猜生日

 

双向if-else 语句

• 如果条件为真，那么走if内部语句，否则走else内部语句

 

EP：

• 产生两个随机整数number1和number2，然后显示给用户，使用户输入数字，并判定其是否正确,如果正确打印“you‘re correct”，否则打印正确错误

 

嵌套if 和多向if-elif-else

In [ ]:

 

if score >= 80:

    gread = 'B'

elif score>=90:

    gread = 'A'

In [9]:

tizhong  = eval(input('体重'))

shengao = eval(input('身高'))

BMI = tizhong / shengao ** 2

if BMI<18.5 :

    print('超清')

elif 18.5<=BMI<25 :

    print('标准')

elif 25<=BMI<30 :

    print('超重')

else:

    print('超级无敌胖')

体重500
身高10000
超清 

逻辑运算符

EP：

• 判定闰年：一个年份如果能被4整除但不能被100整除，或者能被400整除，那么这个年份就是闰年
• 提示用户输入一个年份，并返回是否是闰年
• 提示用户输入一个数字，判断其是否为水仙花数

实例研究：彩票

In [16]:

 

import random

 

In [25]:

 

number = random.randint(10,99)

print(number)

N = input('>>')

number_shi = number // 10

number_ge = number % 10

​

if N[0] == '0':

    N_shi = 0

else:

    N_shi = int(N) // 10

    N_ge = int(N) % 10

​

if number == int(N):

    print('10000')

# elif (number_shi == N_shi or number_shi==N_ge) and (number_ge == N_shi or number_ge==N_ge):

elif number_shi + number_ge == N_shi + N_ge:

    print('3000')

elif (number_ge ==N_ge or number_ge == N_shi) or (number_shi == N_ge or number_shi == N_shi):

    print('1000')

24
>>40
1000

In [3]:

 

a = "05"

a[0]

 

 

Out[3]:

'o'

In [22]:

 

 

05 // 10

 

 

Out[22]:

'J'

In [14]:

 

 

Number = eval(input('>>'))​

bai = Number // 100

shi = Number // 10 % 10

ge = Number % 10

​

if bai**3 + shi **3 + ge **3 == Number:

    print('水仙花')

else:

    print('不是水仙花'

>>123
不是水仙花

In [15]:

 

 

223 // 10

 

Out[15]:

2

Homework

In [3]:

 

import math 

a,b,c = map(float,input('Enter a, b, c :').split(','))

​

if b **2 - 4 *a * c > 0:

   r1 = (-b + math.sqrt (b **2 - 4 * a *c) ) /(2 *a)

   r2 = (-b - math.sqrt ( b **2 - 4 * a *c )) /(2 *a)

   print('The roots are %f and The roots are %f' % (r1, r2))

elif b **2 - 4 *a * c == 0:

   r3 = (-b) /(2 *a)

   print('r3:%d' % r3)

else:

    print('The equation has no real roots')

Enter a, b, c :1,3,1
The roots are -0.381966 and The roots are -2.618034

 

• 

In [4]:

 

import random

​

a =random.randrange(0,99)

b =random.randrange(0,99)

print(a,b)

​

c = int(input('请输入两个数的和:'))

if c == a + b :

    print('程序为真')

else:

    print('程序为假')

 

 

 

11 28
请输入两个数的和:39
程序为真

 

• 3

In [22]:

 

​

today = int(input("Enter today's day:"))

future = int(input("Enter the number of days elapsed since today:"))

week = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday']

futureweek = today + future

a = futureweek % 7

print("Today is %s and the future day is %s"%(week[today],week[a]))

 

Enter today's day:1
Enter the number of days elapsed since today:31
Today is Monday and the future day is Thursday

- 4

In [5]:

a,b,c = map(int,input('Enter a, b, c :').split(','))

if a < b < c:

    print(a,b,c)

elif a < c < b:

    print(a,c,b)

elif b< a< c:

    print(b,a,c)

elif b < c < a:

    print(b,c,a)

elif c < a < b:

    print(c,a,b)

else:

    print(c,b,a)

 

Enter a, b, c :2,7,1
1 2 7

• 5

In [6]:

 

a,b = map(float,input('Enter weight and price 1:').split(','))

c,d = map(float,input('nter weight and price 2 :').split(','))

e =b / a

f = d / c

print(e,f)

if e > f:

    print('package 2 has better price')

else:

    print('package 1 has better price')

Enter weight and price 1:50,24.59
nter weight and price 2 :25,11.99
0.4918 0.4796
package 2 has better price

 

• 6

In [23]:

 

a,b = map(float,input('请输入年和月份: ').split(','))

if a % 4 == 0 and a % 100 != 0 or a % 400 == 0:

    c = 29

else:

    c = 28

if b == 1 or b == 3 or b == 5 or b == 7 or b == 8 or b == 10 or b == 12:

    d = 30 

elif b == 2:

    d = c

else:

    d = 31

print( a,'年', b,'月份有', d,'天')

 

请输入年和月份: 2005,3
2005.0 年 3.0 月份有 30 天

 

• 7

In [7]:

 

import numpy as np 

res1 = np.random.choice(['正面','反面'])

print(res1)

res2 = input('请输入“正面，反面”')

if res1 == res2:

    print('猜测正确')

else:

    print('猜测错误')

反面
请输入“正面，反面”反面
猜测正确

 

• 8

In [10]:

 

import numpy as np ​

res1 = np.random.choice(['0','1','2'])​

res2 = input('请输入“0，1，2”')​

print('scissor ({}) ,rock ({}) '.format(res1,res2))​

if res1 == '0' and res2 == '1':​

    print('res1 胜')​

elif res1 == '1' and res2 == '0':​

    print('res2 胜')​

elif res1 == '0' and res2 == '2':​

    print('res1 胜')   ​

elif res1 == '2' and res2 == '0':​

    print('res2 胜')   ​

elif es1 == '1' and res2 == '2':​

    print('res1 胜')​

elif es1 == '2' and res2 == '1':​

    print('res2 胜')  ​

else:​

    print('平局')

请输入“0，1，2”1
scissor (0) ,rock (1) 
res1 胜

 

• 9

In [25]:

 

 

year = int(input('Enter year:(e.g.,2008):'))

m = int(input('Enter month:1-12:'))

q = int(input('Enter the day of the month:1-31:'))

week = ['Sunday','Monday','Thursday','Wednesday','Thursday','Friday','Saturday']

if m == 1 or m == 2:

    year= year - 1

    m = m+12

    k =  year % 100

    j = year / 100

    h = int(q + (26 * (m+1))/10 + k +(k/4) + (j/4) + (5*j)) % 7

    print('Day of the week is %s'%(week[h]))

else:

    m = m+12

    k =  year % 100

    j = year / 100

    h = int(q + (26 * (m+1))/10 + k +(k/4) + (j/4) + (5*j)) % 7

    print('Day of the week is %s'%(week[h]))

 

Enter year:(e.g.,2008):2012
Enter month:1-12:5
Enter the day of the month:1-31:12
12 20.12
4
Day of the week is Wednesday

 

• 10

In [20]:

 

import numpy as np ​

res1 = np.random.choice(['Ace','2','3','4','5','6','7','8','9','10','Jack','Queen','King'])

res2 = np.random.choice(['梅花''红桃','方片','黑桃'])

print('The card you picked is the ',res1,'of',res2)

The card you picked is the  King of 方片

 

• 11

In [18]:

 

shu = int(input('请输入一个三位数整数：'))

a = shu // 100

b = shu % 10 

if a == b:

    print(shu,'是一个回文数')

else:

    print(shu,'不是一个回文数')

请输入一个三位数整数：121
121 是一个回文数

• 12
• 

In [16]:

 

import math​

a,b,c= map(float,input('Enter three edges:').split(','))

if a + b > c and a + c > b and b + c > a:

    print('The perimeter is  %d' % (a + b + c))

    p = (a + b + c) / 2

else:

    print('不能构成三角形')

 

Enter three edges:1,1,1
The perimeter is  3

 

 

 

 

 

 

​