Initialising an n-length tuple of lists

Question

Is there a more efficient, simpler way to create a tuple of lists of length 'n'?

So in Python, if I wanted to create a list of lists I could do something like:

[[] for _ in range(list_length)]

And to create a tuple of lists of a similar nature I could technically write:

tuple([[] for _ in range(list_length)])

But is this computationally inefficient, could it be written in a nicer way?

Warning: For anyone else who thought it was good idea to put mutable objects such as lists inside a tuple (immutable); it actually appears to be generally faster (computationally) to just use a list (in my case a list of lists).

Devisable

A tuple of lists is an unusual thing to want, outside of some short-term, narrow-scoped uses like function star-arguments. The primary advantage of a tuple is that it's immutable, for use in sets, as dictionary keys, etc. But if a tuple's contents are mutable, the tuple itself can't be used safely in any of those roles. – Enidenigma

Wow, in fact (according to my very sloppy benchmark) it takes ever so slightly longer to create, access and append to the lists in the tuple when compared to doing the same thing with a list of lists. – Devisable

Answer 1

Use a genex instead of a LC.

tuple([] for _ in range(list_length))

Karen

Thanks! For some reason that didn't occur to me. – Devisable

(genex stands for generator expression, LC stands for list comprehension) – Touchline

Answer 2

Try this:

tuple = (elements,) * list_length

Reconcilable

It's bad to name your variables the same as built-in data types or functions. – Fatling

Note that ([],)*3 will create ([],[],[]). However, the lists within the tuple are not independent and changes on any of them will reflect on all of them. – Rojo