如何将元组转换成字典？

Question

i'm using Python 2.5 and Win XP. i have a tuple as below:

>>> a
(None, '{1: 2, 2: 4, 3: 6, 4: 8, 5: 10, 6: 12}')
>>> a[1]
'{1: 2, 2: 4, 3: 6, 4: 8, 5: 10, 6: 12}'
>>> 

i want to convert tuple a[1] to dictionary because i want to use the key and value. pls help to advise. tq

Answer 1

>>> import ast
>>> ast.literal_eval(a[1])
{1: 2, 2: 4, 3: 6, 4: 8, 5: 10, 6: 12}

Answer 2

First split the string on comma. Iterate over all parts. Split each part on colon. Convert the strings into integers. Add the second integer as value for the first integer as key.

Answer 3

If you trust the source of a[1] you can use eval :

dictionary = eval(a[1])

Otherwise you can use json (or simplejson in Python 2.5: see here ) :

import json
dictionay = json.loads(a[1])

Note : it mostly depends on how you got the string: if it comes from a repr and cannot be hacked, eval may be good. If it came from json.dumps (which would result in a different string), you should use json.loads .

Answer 4

There is another way to do it, without using any imports.

A simple list comprehension (temp):

>>> a
(None, '{1: 2, 2: 4, 3: 6, 4: 8, 5: 10, 6: 12}')
>>> a[1]
'{1: 2, 2: 4, 3: 6, 4: 8, 5: 10, 6: 12}'
>>> temp = [[int(c) for c in b.split(":")] for b in a[1].strip('{}').split(",")]
>>> a_dict = dict(temp)
>>> a_dict[1]
2
>>> a_dict[2]
4

Answer 5

The dict() constructor builds dictionaries directly from lists of key-value pairs stored as tuples. When the pairs form a pattern, list comprehensions can compactly specify the key-value list.

dict([('sape', 4139), ('guido', 4127), ('jack', 4098)]) {'sape': 4139, 'jack': 4098, 'guido': 4127} dict([(x, x**2) for x in (2, 4, 6)]) # use a list comprehension {2: 4, 4: 16, 6: 36}

Copy & Paste from: http://docs.python.org/tutorial/datastructures.html