Python dictionary

From Augix' Wiki

• Python dictionary can only use immutable elements as keys, therefore list can not be used as keys, but tuples with immutable elements can.

• create dictionary

l = dict(a=1,b=2,c=3)
l = dict(zip(['a','b','c'],[1,2,3]))
dict(zip('abc',[1,2,3]))

• Iterating Through a Dictionary

>>> import os
>>> for k, v in os.environ.items():     
...     print "%s=%s" % (k, v)

• Double dictionary

reference: create a double dictionary in python

the following WON'T work

>>> x = dict()
>>> x[1][1] = “foo”

instead, one can use this:

>>> x = dict()
>>> x[1,1] = “foo”

note that, tuple (1,1) is used as key.

• find the key to the max and min value

suppose d is the dict.

max(d,key = lambda a: d.get(a))