When is it better to use zip instead of izip?

Question

When is it better to use zip instead of itertools.izip?

Answer 1

The itertools library provides "iterators" for common Python functions. From the itertools docs, "Like zip() except that it returns an iterator instead of a list." The I in izip() means "iterator".

Python iterators are a "lazy loaded" sequence that saves memory over regular in-memory list. So, you would use itertools.izip(a, b) when the two inputs a, b are too big to keep in memory at one time.

Look up the Python concepts related to efficient sequential processing:

"generators" & "yield"
"iterators"
"lazy loading"