Replacing multiple occurrences in nested arrays

Replacing multiple occurrences in nested arrays

I've got this python dictionary "mydict", containing arrays, here's what it looks like :

mydict = dict(     one=['foo', 'bar', 'foobar', 'barfoo', 'example'],      two=['bar', 'example', 'foobar'],      three=['foo', 'example']) 

i'd like to replace all the occurrences of "example" by "someotherword".

While I can already think of a few ways to do it, is there a most "pythonic" method to achieve this ?

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for arr in mydict.values():     for i, s in enumerate(arr):         if s == 'example':             arr[i] = 'someotherword' 

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If you want to leave the original untouched, and just return a new dictionary with the modifications applied, you can use:.
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replacements = {'example' : 'someotherword'}  newdict = dict((k, [replacements.get(x,x) for x in v])                  for (k,v) in mydict.iteritems()) 
This also has the advantage that its easy to extend with new words just by adding them to the replacements dict.

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If you want to mutate an existing dict in place, you can use the same approach:.
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for l in mydict.values():     l[:]=[replacements.get(x,x) for x in l] 
However it's probably going to be slower than J.F Sebastian's solution, as it rebuilds the whole list rather than just modifying the changed elements in place..


Here's another take:.
for key, val in mydict.items():     mydict[key] = ["someotherword" if x == "example" else x for x in val] 
I've found that building lists is very fast, but of course profile if performance is important..

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