Egor> i know how to get item by key ... Egor> but i wonder how to get key by item
Assuming your dictionary defines a one-to-one mapping, just invert it:
>>> forward = {10 : 50, 2 : 12, 4 : 43} >>> reverse = dict([(v,k) for (k,v) in forward.iteritems()]) >>> print forward {10: 50, 4: 43, 2: 12} >>> print reverse {50: 10, 43: 4, 12: 2}
That doubles your storage, so you'll have to trade that off against the speed gain of not having to loop over the entire dictionary.
Skip
If some keys has the same value as the item this will cause problems because keys in your result dictionary can be overwritten. Could it be a option to build the result dictionary as a dictionary with the values as the keys, and lists of keys as the value. Perhaps you need to use a loop for this.
-- -------------------------------------- Ola Natvig <[EMAIL PROTECTED]> infoSense AS / development -- http://mail.python.org/mailman/listinfo/python-list
