python:字典被覆盖

下面代码中字典数据的值被覆盖了，虽然key不同，但覆盖的原因可能是什么。

#!/usr/local/bin/python2.7 
data={} 
marks = {} 
subjects = ["Tamil","English","Maths","Science","Social"] 
 
for i in range(1,3): 
  print 'Enter marks for student%d'%i 
  for subject in subjects: 
    marks[subject] = input("Enter the " + subject + " marks: ") 
 
  data[i]={'marks':marks} 
  print data 

代码输出:

Enter marks for student1 
Enter the Tamil marks:  10 
Enter the English marks:  20 
Enter the Maths marks:  30 
Enter the Science marks:  40 
Enter the Social marks:  50 
{1: {'marks': {'Maths': 30, 'Science': 40, 'Social': 50, 'Tamil': 10, 'English': 20}}} 
Enter marks for student2 
Enter the Tamil marks:  11 
Enter the English marks:  12 
Enter the Maths marks:  13 
Enter the Science marks:  14 
Enter the Social marks:  15 
{1: {'marks': {'Maths': 13, 'Science': 14, 'Social': 15, 'Tamil': 11, 'English': 12}}, 2: {'marks': {'Maths': 13, 'Science': 14, 'Social': 15, 'Tamil': 11, 'English': 12}}} 
{1: {'marks': {'Maths': 13, 'Science': 14, 'Social': 15, 'Tamil': 11, 'English': 12}}, 2: {'marks': {'Maths': 13, 'Science': 14, 'Social': 15, 'Tamil': 11, 'English': 12}}} 

请您参考如下方法:

您正在重复使用同一个字典，只需在每次迭代中使用一个新字典即可:

#!/usr/local/bin/python2.7 
data={} 
subjects = ["Tamil","English","Maths","Science","Social"] 
 
for i in range(1,3): 
  print 'Enter marks for student%d'%i 
  marks = {} 
  for subject in subjects: 
    marks[subject] = input("Enter the " + subject + " marks: ") 
 
  data[i]={'marks':marks} 
  print data