extending dictonary

[InvisibleRoads Patrol]

On Sat, 21 Nov 2009 09:25:38 +0100, nospam <"knutjbj(nospam)"@online.no>
wrote:
> Is there any way to extend the dictonary in such manner that I can 
> insert muliplay value to each keys and return one of the value as the 
> default value. I would like to have similar syste that I drawed out
below.
> 
> 
> tree[nucelotide_postionc][nucleotide]=default(value subtree) This should 
> be returned when doing lookup without any
> tree[nucelotide_postionc][nucleotide]=Postive value
> tree[nucelotide_postionc][nucleotide]=Negative value


You could use the collections.defaultdict method.

>>> >>> import collections
>>> >>> example1 = collections.defaultdict(int)
>>> >>> example1[1]
0

>>> >>> example2 = collections.defaultdict(list)
>>> >>> example2[1]
[]

>>> >>> example3 = collections.defaultdict(dict)
>>> >>> example3[1]
{}

>>> >>> # Make nested default dictionary
>>> >>> def getNewOuterDictionary():
...    return collections.defaultdict(getNewInnerDictionary)
>>> >>> def getNewInnerDictionary():
...    return collections.defaultdict([])
>>> >>> example4[1][1]
[]       

Hope that helps.


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