Help with dictionaries and multidimensial lists

Terry Reedy tjreedy at
Tue Jun 23 20:37:59 CEST 2009

Cameron Pulsford wrote:
> Hey all, I have a dictionary that looks like this (small example version)
> {(1, 2): 0} named a
> so I can do a[1,2] which returns 0. What I also have is a list of 
> coordinates into a 2 dimensional array that might look like this b = 
> [[1,2]]. Is there anyway I can call a[b[0]] and have it return 0?

Unless you are mutating your coordinate pairs in place, which you very 
seldom would *have to* do, I would make them tuples.
b = [ (1,2), (3,5), ...]
This would even save a bit of memory.

I prefer this to converting list pairs to tuple pairs  on access.


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