Python 入门练习 (list, array, for loop, while loop, numpy)

1- Create an empty list name “mylist”

1 mylist = [] 
2 mylist    # print mylist

2- Append the following floating point numbers to the list: 4.0, 2.2, 5.7, 3.5 (use mylist.append() 4 times )

1 mylist.append(4.0)
2 mylist.append(2.7)
3 mylist.append(5.7)
4 mylist.append(3.5)
5 mylist

3- Use a “for loop” to print the values contained in “mylist”, one at a time.

1 len_mylist = len(mylist)
2 
3 for i in range(len_mylist):
4     print('mylist','[',i,']','=',mylist[i])
5     
6 """  # three quation marks mean comment for several lines
7 for i in mylist
8     print(i)
9 """ # three quotation marks mean comment for several lines

4- Use a “while loop” to print the values contained in “mylist”, one at a time.

1 i = 0
2 while i < len_mylist:
3     print('mylist','[',i,']','=',mylist[i])
4     i += 1

5- Create a numpy array using the values contained in “mylist”. Name it “myarray”.

1 import numpy as np
2 myarray=np.array(mylist)
3 myarray

6- Use a “for loop” to find the maximum value in “mylist”

1 maxvalue = mylist[0]
2 for i in range(len_mylist):
3     if maxvalue < mylist[i]:
4         maxvalue = mylist[i]
5 print('The maximum value is ', maxvalue)

7- Use a “for loop” to find the minimum value in “mylist”.

1 minvalue = mylist[0]
2 for i in range(len_mylist):
3     if minvalue > mylist[i]:
4         minvalue = mylist[i]
5 print('The minimum value is ', minvalue)
1 # another example
2 def min(mylist):
3     minvalue = mylist[0]
4     for i in range(len(mylist)):
5         if mylist[i]<minvalue:
6             minvalue = mylist[i]           
7     return (minvalue)
8 print('The minimum value is =', min(mylist))

8- Create the following list mylist2=[[1,2,3],[4,5,6],[7,8,9]]

1 mylist2 = [ [1,2,3], [4,5,6], [7,8,9] ]
2 mylist2
3 print(mylist2[0][0])

9- Using the modulus (%) command, print the index of all odd numbers in “mylist2”

1 for i in range(3):
2     for j in range(3):
3         odd_num = mylist2[i][j]
4         if (odd_num % 2) == 1:
5             print( '(', i, j ,')' )

 

posted @ 2020-09-26 09:09  cfdchen  阅读(267)  评论(0)    收藏  举报