Access to items in lists in a python dictionary

Question

I have a dictionary that has keys associated with lists.

mydict = {'fruits': ['banana', 'apple', 'orange'], 'vegetables': ['pepper', 'carrot'], 'cheese': ['swiss', 'cheddar', 'brie']} 

What I want to do is use the if statement, which, if I look for the element and it in any of the lists in the dictionary, it will return the key. This is what I tried:

 item = cheddar if item in mydict.values(): print key 

but he does nothing, the conclusion should be:

 cheese 

This seems like a simple thing, but I just can't figure it out. Any help is awesome.

Answer 1

You will need to use for , a simple if not enough to check an unknown set of lists:

 for key in mydict.keys(): if item in mydict[key]: print key 

The approach without an explicit for expression will be possible as follows:

 foundItems = (key for key, vals in mydict.items() if item in vals) 

which returns all the keys associated with item . But inside, there is still some kind of iteration happening.

Answer 2

 mydict = {'fruits': ['banana', 'apple', 'orange'], 'vegetables': ['pepper', 'carrot'], 'cheese': ['swiss', 'cheddar', 'brie']} item = "cheddar" if item in mydict['cheese']: print ("true") 

this works, but you have to refer to keys in the dictionary, for example cheese, vegetables, etc., instead, because of how you made the dictionary, hope this helps!

Answer 3

 mydict = {'fruits': ['banana', 'apple', 'orange'], 'vegetables': ['pepper', 'carrot'], 'cheese': ['swiss', 'cheddar', 'brie']} item = "cheddar" for key, values in mydict.iteritems(): if item in values: print key 

If you are going to do such a search, I think you can create a reverse index for the original mydict to speed up the query:

 reverse_index = {} for k, values in mydict.iteritems(): for v in values: reverse_index[v] = k print reverse_index.get("cheddar") print reverse_index.get("banana") 

Thus, you do not need to move the values list each time to find an element.