dict.update

[Tino Wildenhain]

Mike P wrote:
> Hi All,
> 
> I have two dictionaries e.g
> dict1 = {123:3,234:5,456:3}
> dict2 = {123:4,157:2,234:5,456:3,567:2}
> 
> I want to merge these two dictionaries together so i have a resultant
> dictionary of:
> 
> dict3 = {123:[4,3],157:[2,0],234:[5,5],456:[3,3],567:[2,0]}
> 
> As later on i want to write a csv file that would have the form
> 
> id      var1  var2
> 123     4      3
> 157     2      0
> 
> i looks like the dict.update looks almost there but i can't get it to
> work properly, can anyone offer any advise?

result=dict((key,(dict1.get(key,None),
            dict2.get(key,None)))
       for key in set(dict1.keys()+dict2.keys())
      )

(untested)

should provide you with a resulting dictonary with tuples
where [0] is var1 and [1] is var2, None for values not
in one of the dictionaries (you can put in 0 if you prefer).

You can use it like so to generate your output:

allitems=result.items()
allitems.sort() # sort based on keys as first tuple element

for (key,(var1,var2)) in allitems:
     print key,var1,var2

HTH
Tino

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