How to extend/concatenate two iterators in Python
Question:
I want concatenate two iterators in an efficient way.
Suppose we have two iterators (in Python3)
l1 = range(10) # iterator over 0, 1, ..., 9
l2 = range(10, 20) # iterator over 10, 11, ..., 19
If we convert them to lists, it is easy to concatenate like
y = list(l1) + list(l2) # 0, 1, ,..., 19
However, this can be not efficient.
I would like to do something like
y_iter = l1 + l2 # this does not work
What is the good way to do this in Python3?
Answers:
Use itertools.chain:
from itertools import chain
y_iter = chain(l1, l2)
It yields all the items from l1 and then all the items from l2. Effectively concatenating the sequence of yielded items. In the process it consumes both.
you can use the chain() function provided by the itertools
itertools.chain()
I want concatenate two iterators in an efficient way.
Suppose we have two iterators (in Python3)
l1 = range(10) # iterator over 0, 1, ..., 9
l2 = range(10, 20) # iterator over 10, 11, ..., 19
If we convert them to lists, it is easy to concatenate like
y = list(l1) + list(l2) # 0, 1, ,..., 19
However, this can be not efficient.
I would like to do something like
y_iter = l1 + l2 # this does not work
What is the good way to do this in Python3?
Use itertools.chain:
from itertools import chain
y_iter = chain(l1, l2)
It yields all the items from l1 and then all the items from l2. Effectively concatenating the sequence of yielded items. In the process it consumes both.
you can use the chain() function provided by the itertools
itertools.chain()