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For each, say whether it is an iterable that is not an iterator, or an iterator, and whether it can…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each, say whether it is an iterable that is not an iterator, or an iterator, and whether it can be looped over twice.
[1, 2, 3]iter([1, 2, 3])"abc"range(5)(n for n in range(3))- an open file
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. An iterator is what iter returns, and it is used up after one pass. An iterable can give a fresh iterator each time.
- A list: an iterable. It can be looped over many times.
iter([1, 2, 3]): an iterator. Once.- A text: an iterable. Many times.
- A
range: an iterable. Many times. - A generator expression: an iterator. Once.
- An open file: an iterator (it gives its lines, and remembers where it is). Once, unless you start again.
Check. Try list(x) twice on each. The iterators give an empty list the second time.
Answer: iterable (many), iterator (once), iterable (many), iterable (many), iterator (once), iterator (once).
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