Autarchy of the Private Cave » looping https://bogdan.org.ua Tiny bits of bioinformatics, [web-]programming etc Wed, 28 Dec 2022 16:09:04 +0000 en-US hourly 1 https://wordpress.org/?v=3.8.27 Useful Python looping techniqueshttps://bogdan.org.ua/2007/09/26/useful-python-looping-techniques.html https://bogdan.org.ua/2007/09/26/useful-python-looping-techniques.html#comments Wed, 26 Sep 2007 09:21:00 +0000 http://bogdan.org.ua/2007/09/26/useful-python-looping-techniques.html These are all excerpts from the Python documentation.

To synchronously and simultaneously loop over two sequences:

  1. questions = ['name', 'quest', 'favourite colour']
  2. answers = ['Lancelot', 'the holy grail', 'blue']
  3.  
  4. for q, a in zip(questions, answers):
  5.     print 'What is your %s?  It is %s.' % (q, a)

To loop over a sequence with both key and value:

  1. for i, v in enumerate(['tic', 'tac', 'toe']):
  2.     print i, v

To loop over dictionary, again with key and value:

  1. knights = {'gallahad': 'the pure', 'robin': 'the brave'}
  2.  
  3. for k, v in knights.iteritems():
  4.     print k, v

To loop over some sorted sequence, but without modifying the original sequence (beware the use of set() in this example):

  1. basket = ['apple', 'orange', 'apple', 'pear', 'orange', 'banana']
  2.  
  3. for f in sorted(set(basket)):
  4.     print f

For looping sorted dictionaries, see also How to sort Python dict (dictionary).

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