在python中打印字典的原始输入顺序

Question

How do I print out my dictionary in the original order I had set up?

If I have a dictionary like this:

smallestCars = {'Civic96': 12.5, 'Camry98':13.2, 'Sentra98': 13.8}

and I do this:

for cars in smallestCars:
    print cars

it outputs:

Sentra98
Civic96
Camry98

but what I want is this:

Civic96
Camry98
Sentra98

Is there a way to print the original dictionary in order without converting it to a list?

Answer 1

A regular dictionary doesn't have order. You need to use the OrderedDict of the collections module, which can take a list of lists or a list of tuples, just like this:

import collections

key_value_pairs = [('Civic86', 12.5),
                   ('Camry98', 13.2),
                   ('Sentra98', 13.8)]
smallestCars = collections.OrderedDict(key_value_pairs)

for car in smallestCars:
    print(car)

And the output is:

Civic96
Camry98
Sentra98

Answer 2

Dictionaries are not required to keep order. Use OrderedDict .

Answer 3

When you create the dictionary, python doesn't care about in what order you wrote the elements and it won't remember the order after the object is created. You cannot expect it(regular dictionary) to print in the same order. Changing the structure of your code is the best option you have here and the OrderedDict is a good option as others stated.

Answer 4

>>> for car in sorted(smallestCars.items(),key=lambda x:x[1]):
...     print car[0]
... 
Civic96
Camry98
Sentra98

Answer 5

You can use a tuple (nested) array to do this:

smallestCars = [['Civic86', 12.5],
               ['Camry98', 13.2],
               ['Sentra98', 13.8]]

for car, size in smallestCars:
    print(car, size)

# ('Civic86', 12.5)
# ('Camry98', 13.2)
# ('Sentra98', 13.8)