More Pythonic Way to Run a Process X Times

Question

Which is more pythonic   While loop   count   0 while count  lt  50      print  Some thing      count   count   1   For loop   for i in range 50       print  Some thing    Edit  not duplicate because this has answers to determine which is clearer  vs  how to run a range without  i  -- even though that ended up being the most elegant

User · Accepted Answer

Personally   for   in range 50       print  Some thing    if you don t need i  If you use Python  lt  3 and you want to repeat the loop a lot of times  use xrange as there is no need to generate the whole list beforehand

User · Answer

If you are after the side effects that happen within the loop  I d personally go for the range   approach   If you care about the result of whatever functions you call within the loop  I d go for a list comprehension or map approach  Something like this   def f n       return n   n  results    f i  for i in range 50     or using map  results   map f  range 50

User · Answer

The for loop is definitely more pythonic  as it uses Python s higher level built in functionality to convey what you re doing both more clearly and concisely  The overhead of range vs xrange  and assigning an unused i variable  stem from the absence of a statement like Verilog s repeat statement  The main reason to stick to the for range solution is that other ways are more complex  For instance   from itertools import repeat  for unused in repeat None  10       del unused     redundant and inefficient  the name is clear enough     print  This is run 10 times    Using repeat instead of range here is less clear because it s not as well known a function  and more complex because you need to import it  The main style guides if you need a reference are PEP 20 - The Zen of Python and PEP 8 - Style Guide for Python Code    We also note that the for range version is an explicit example used in both the language reference and tutorial  although in that case the value is used  It does mean the form is bound to be more familiar than the while expansion of a C-style for loop

User · Answer

There is not a really pythonic way of repeating something   However  it is a better way   map lambda index do something    xrange 10     If you need to pass the index then   map lambda index do something index   xrange 10     Consider that it returns the results as a collection  So  if you need to collect the results it can help

User · Answer

How about   while BoolIter N  default True  falseIndex N-1       print  some thing    or in a more ugly way   for   in BoolIter N       print  doing somthing    or if you want to catch the last time through   for lastIteration in BoolIter N  default False  trueIndex N-1       if not lastIteration          print  still going      else          print  last time    where   class BoolIter object        def   init   self  n  default False  falseIndex None  trueIndex None  falseIndexes     trueIndexes     emitObject False           self n   n         self i   None         self  default   default         self  falseIndexes set falseIndexes          self  trueIndexes set trueIndexes          if falseIndex is not None              self  falseIndexes add falseIndex          if trueIndex is not None              self  trueIndexes add trueIndex          self  emitObject   emitObject       def   iter   self           return self      def next self           if self i is None              self i   0         else              self i    1         if self i    self n              raise StopIteration         if self  emitObject              return self         else              return self   nonzero          def   nonzero   self           i   self i         if i in self  trueIndexes              return True         if i in self  falseIndexes              return False         return self  default      def   bool   self           return self   nonzero

[python] More Pythonic Way to Run a Process X Times

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