Replacing list item with contents of another list

Question

Similar to this question, but instead of replacing one item with another, I\'d like to replace any occurrences of one item with the contents of a list.

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Answer 1

Different approach: when I'm doing replacements, I prefer to think in terms of dictionaries. So I'd do something like

>>> orig = [ 'a', 'b', 'c', 'd' ]
>>> rep = {'c': ['x', 'y', 'z']}
>>> [i for c in orig for i in rep.get(c, [c])]
['a', 'b', 'x', 'y', 'z', 'd']

where the last line is the standard flattening idiom.

One advantage (disadvantage?) of this approach is that it'll handle multiple occurrences of 'c'.

[update:]

Or, if you prefer:

>>> from itertools import chain
>>> list(chain.from_iterable(rep.get(c, [c]) for c in orig))
['a', 'b', 'x', 'y', 'z', 'd']

On the revised test case:

>>> orig = [ 'a', 'b', 'c', 'd', 'c' ]
>>> rep = {'c': ['x', 'y', 'z']}
>>> list(chain.from_iterable(rep.get(c, [c]) for c in orig))
['a', 'b', 'x', 'y', 'z', 'd', 'x', 'y', 'z']