On 2016-05-10 23:36, DFS wrote:
[snip]
If lists are still being created:
* at every moment in time, len(list1) returns a length that doesn't
change even if data is added to the list after the call to len().
Example: If the list has 100 items in it at the point len(list) is called:
for i in range(len(list1))
will never iterate more than 100x, no matter how large list1 grows to.
Caveat: since list1 may be bigger or smaller than the other lists at
that moment in time, an error may occur when using list2[i], list3[i].
Is that all correct as you understand it?
Yes.
* at every moment in time, zip(list1, list2, etc) will return a fixed,
same-length lists of tuples, which doesn't change even if data is added
to any of the lists after the call to zip().
Example: if the lists have 100, 97 and 102 items in them at the point
zip(lists) is called:
for item1, item2, item3 in zip(list1, list2, list3)
will never iterate beyond 97x, even if the lists grow while the
enumeration is occurring.
Caveat: since zip() possibly truncates lists, the results - the usage of
the data - could be completely invalid.
Is that all correct as you understand it?
In Python 2, zip iterates through the arguments immediately and returns
a list of tuples, so the answer is yes.
In Python 3, zip returns a lazy iterator (like itertools.izip in Python
2) that gets the values from the arguments _on demand_, so the answer is no.
[snip]
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