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 Python syntax
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.. contents::
   :local:

List comprehension
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List comprehension produce complete list with compact syntax::

  [x**2 for x in xrange(1,10)]
  [x+y for x in xrange(1,10) for y in xrange(1,10)]
  [x-y for x in xrange(1,10) for y in xrange(1,10) if x>y]

  xlist = [x**2 for x in xrange(1,10)]
  print xlist[0], xlist[2], xlist[-1]
  print xlist[2:4]
  print sum(xlist), sum(xlist)

Generator expression
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Generator expression produce generator with compact syntax::

  (x**2 for x in xrange(1,10))
  (x+y for x in xrange(1,10) for y in xrange(1,10))

  print [x for x in (x**2 for x in xrange(1,10))]

  xgen = (x**2 for x in xrange(1,10))
  try:
      xgen[0]
  except TypeError:
      print "'generator' object has no attribute '__getitem__'"
  print sum(xlist), sum(xlist)

Parentheses is required only if expression is ambiguous.