Question about `list.insert`

Terry Reedy tjreedy at
Fri Feb 7 01:40:00 CET 2014

On 2/6/2014 6:59 PM, cool-RR wrote:
> Hi,
> I'm curious. If I append an item to a list from the left using
> `list.insert`, will Python always move the entire list one item to
> the right (which can be super-slow) or will it check first to see
> whether it can just allocate more memory to the left of the list and
> put the item there, saving a lot of resources?

"It depends on the implementation"

Assume O(n), which I am sure it is for CPython,  but easy enough to check.

Terry Jan Reedy

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