Does [:] slice only make shallow copy of a list?

Question

I have experienced peculiar bugs from this [:] copy.

The docs say [:] makes only a shallow copy but seems:

a = [1,2,3]
id(         


        

Answer 1

Numpy defines what what a slice returns differently to the standard python library. This is because numpy is made to work with huge amounts of data. Copying these huge arrays is not always wanted, especially if the user only wanted a temporary view of the array. For instance, arr[:100].sum() sums the first 100 elements, without having to create a temporary shallow copy of the first 100 elements. Note that temporary views are only created for a basic slice.

See the documentation for more details.