How to find the index of value in python list?

Why does Python change the order of tuple elements returned in calls to items() and keys() on a dict?

• Hi guys. I am currently learning Python, and I have found a weird problem with lists and dictionaries, maybe you can help me nail it down: Code below: ------------------------------------------------------------------------------------- women = {"Cute":"Alyssa",            "Beatufiul":"Sayana", #ignore the typo in "Beautuful".            "Happy":"Boni"} print women #prints the whole dictionary. print loliDic.keys() #Prints the keys of the dictionaries in a list. print loliDic.values() #Prints the values of each key in a list. #The problem starts below... hmm = women.items() #Assigns "hmm" a list of touples of the key-value relationship of each element in my dictionary. print hmm[0] ----------------------------------------------------------------------------------- Now, you may have seen that I am trying to print hmm[0] which works BTW, but I don't think its working as it should. I was expecting that: * hmm[0] would print ("Cute", "Alyssa") * hmm[1] would print ("Beautuful", "Sayana") * hmm[2] would print ("Happy", "Boni") But instead: * hmm[0] prints ("Beautuful", "Sayana") * hmm[1] prints ("Cute", "Alyssa") * hmm[2] prints ("Happy", "Boni") - This one being the only right value. Can someone tell me why is that happening? I keep analyzing my code but I can't find a single logical reason for it to print the touples in that weird order.

• Answer:

  Short answer: Python dictionaries are not ordered, and you should not expect any particular order to come out when you call items() or keys(). Longer answer: Python dictionaries are hash tables, which are not ordered. When you insert elements into the hash table, each key is hashed (using hash()) to a hash value. Here, hash() only depends on the key, so regardless of the order in which the items are inserted, they are stored in the same locations in the hash table. Then, items() or keys() returns the items in whatever order they happen to be stored in.