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  • python101
    New Member
    • Sep 2007
    • 90
    #1

    list question

    I would like to write a function test(data) to test whether the list has two or more elements refer to the same underlying object
    [code=python]
    >>>a = range(2)
    >>>b = range(4)
    >>>c = range(2)
    >>>test([a,b,c])
    False
    >>>test([a,b,c,b]) #b appears 2 times
    True
    [/code]
    If it is a list of numbers or a list of strings like
    [1,2,3,4]
    ['A','B']
    I can write it but if it is a list contains many other lists I can't
    Tags: None
    • bvdet
      Recognized Expert Specialist
      • Oct 2006
      • 2851
      #2
      Originally posted by python101
      I would like to write a function test(data) to test whether the list has two or more elements refer to the same underlying object
      [code=python]
      >>>a = range(2)
      >>>b = range(4)
      >>>c = range(2)
      >>>test([a,b,c])
      False
      >>>test([a,b,c,b]) #b appears 2 times
      True
      [/code]
      If it is a list of numbers or a list of strings like
      [1,2,3,4]
      ['A','B']
      I can write it but if it is a list contains many other lists I can't
      There is a difference between 'referring to the same underlying object' and two objects being equal.[code=Python]>>> a = range(4)
      >>> b = range(4)
      >>> a is b
      False
      >>> a == b
      True
      >>> b = a
      >>> a is b
      True
      >>> [/code]A list is an object like any other, and you can compare for equivalence. Are you wanting to check the lists inside your list recursively?

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