如何使用for循环遍历字典？

Question

I want to decompress a dictionary and a list into a sentence. For example:

newlist = [1, 2, 3, 4, 5, 6]
new_dictionary = {'code': 2, 'help': 6, 'broken': 4, 'is': 3, 'please': 5, 'my': 1}

The original sentence is 'My code is broken please help' . The list shows the positions that the words appear within the sentence. The dictionary stores the word and the position that the word associates with.

The goal is to iterate over the dictionary until the matches the number in the list. Once this happens, the key that matches to the value is added to a list. This will continue to happen until there are no more numbers in the list. The list is then converted into a string and printed to the user.

I would imagine that something like this would be the solution:

for loop in range(len(newlist)):
    x = 0
    for k,v in new_dictionary.items():
         if numbers[x] == v:
              original_sentence.append(k)
         else:
              x = x + 1

print(original_sentence)

However, the code just prints an empty list. Is there any way of re-wording or re-arranging the for loops so that the code works?

Answer 1

Invert the dictionary and proceed. Try the following code.

>>> d = {'code': 2, 'help': 6, 'broken': 4, 'is': 3, 'please': 5, 'my': 1}
>>> numbers = [1, 2, 3, 4, 5, 6]
>>> d_inv = {v:k for k,v in d.items()}
>>> ' '.join([d_inv[i] for i in numbers])
'my code is broken please help'

Answer 2

I assume you don't want to invert the dictionary, so you can try something like this:

dictionary = {'code': 2, 'help': 6, 'broken': 4, 'is': 3, 'please': 5, 'my': 1}
numbers = [1, 2, 3, 4, 5, 6]

sentence = []
for number in numbers:
    for key in dictionary.keys():
        if dictionary[key] == number:
            sentence.append(key)
            break

Answer 3

Sorted the dict with using the values.

import operator
new_dictionary = {'code': 2, 'help': 6, 'broken': 4, 'is': 3, 'please': 5, 'my': 1}
sorted_x = sorted(new_dictionary.items(), key=operator.itemgetter(1))
print ' '.join(i[0] for i in sorted_x)

result

'my code is broken please help'

The whole code in single line.

In [1]: ' '.join([item[0] for item in sorted(new_dictionary.items(), key=operator.itemgetter(1))])
Out[1]: 'my code is broken please help'