simple question about dictionaries

[Bruno Desthuilliers]

skazhy a écrit :
> hi, i am new to python, so i've a really simple question about
> dictionaries.
> if i have a dictionary and I make have an input after it (to input
> numbers) can i get the key of value that was in input?

What if many keys are associated with a same value, ie:
d = {'a':100, 'b':200, 'c':100}


> somehting like this:
> dict = { "key1"=100,"key2"=200,"key3"=300}

1/ don't use 'dict' as an indentifier - this shadows the builtin dict type.

2/ the 'dict literal' syntax is:

d = {'key1":100, "key2": 200, "key3":300}

> a = input()
> print 'the key of inputted value is', dict['a']
 >
> this syntax of course is wrong, but i hope you got the point..

Assuming you don't have duplicate values, you just need to build a 
reverse dictionnary, that is using values as keys and keys as values, 
then lookup this dictionnary. The first operation can be done in one 
single line.

reversed_d = dict((value, key) for key, value in d.items())