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pythonlistprepend

How do I prepend to a short python list?


list.append() appends to the end of a list. This explains that list.prepend() does not exist due to performance concerns for large lists. For a short list, how do I prepend a value?


Solution

  • The s.insert(0, x) form is the most common.

    Whenever you see it though, it may be time to consider using a collections.deque instead of a list. Prepending to a deque runs in constant time. Prepending to a list runs in linear time.