Converting the keys of a dictionary from numeric to string

[pozz]

I have a dictionary where the keys are numbers:

mydict = { 1: 1000, 2: 1500, 3: 100 }

I would like to convert keys from number to string representation:

mydict = { "apples": 1000, "nuts": 1500, "tables": 100 }

Of course, somewhere I have the association between key-numbers and 
key-strings, maybe in another dictionary:

keydict = { 1: "apples", 2: "nuts", 3; "tables" }

How could I make the conversion? My solution:

keydict = { 1: "Joseph", 2: "Michael", 3: "John" }
mydict = { 1: 1000, 2: 2000, 3: 3000 }
newdict = {}
for k in mydict.keys():
	newdict.update({keydict[k]: mydict[k]})
print(newdict)

I tried changing just mydict (without creating newdict), without success.