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pythonlistindices

How to add indices to a list?

For example, I have a list = ['a', 'b', 'c'].
What I want is a list indexed(list) == [(1, 'a'), (2, 'b'), (3, 'c)].

Is there a builtin or module for this?

Solution

  • You can use the built-in function enumerate to achieve that.

    In [1]: a = ['a', 'b', 'c']

In [2]: b = [(idx, item) for idx,item in enumerate(a)]

In [3]: b
Out[3]: [(0, 'a'), (1, 'b'), (2, 'c')]

    Note: the default indice would start with 0, but you could try to add start=1 to config that, e.g. 

    In [4]: c = [(idx, item) for idx,item in enumerate(a, start=1)]

In [5]: c
Out[5]: [(1, 'a'), (2, 'b'), (3, 'c')]

    Hope it helps.