idiom for initial list of lists

[Dan Schmidt]

Robin Becker <robin at jessikat.fsnet.co.uk> writes:

| What's the correct way to initialise a list of lists I find that the
| natural [[]]*n doesn't work eg
| >>> S=[[]]*5
| >>> S
| [[], [], [], [], []]
| >>> S[0].append(1)
| >>> S
| [[1], [1], [1], [1], [1]]
| 
| so I'm forced to use the rather pedantic
| S=[]
| for i in range(n): S[i].append([])

How about

  S = map (lambda x : [], range(5))

Or in Python 2.0,

  S = [[] for x in range(5)]

-- 
                 Dan Schmidt | http://www.dfan.org
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