Return an iterator after modification

Question

I have an iterator result in one function and I need to return an iterator after making some changes to the objects in result from that function. I don't want to iterate over the result as it is causing performance degradation. I want to perform that operation on the fly for each item in the result.

This is the code which iterates over the result to do that operation.

sols = []
# Get rid of this loop
for sol in result:
    sols.append(dict((symbols[abs(lit) - 1], lit > 0) for lit in sol))
# Return iterator object
return (sol for sol in sols)

Have you tried `yield` keyword http://stackoverflow.com/questions/231767/what-does-the-yield-keyword-do-in-python — Mikko Ohtamaa, Aug 19 '15 at 08:44

Frerich Raabe · Accepted Answer · 2015-08-19T08:57:46.157

2

You're almost there. Just don't store the values in a sols list:

def f(result):
  return (dict((symbols[abs(lit) - 1], lit > 0) for lit in sol) for sol in result)

This yields (no pun intended) a generator which incrementally traverses the given result parameter.

edited Aug 19 '15 at 08:57

answered Aug 19 '15 at 08:44

Frerich Raabe

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Return an iterator after modification

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