email0.ya <email0...@yandex.com> added the comment:
Above is a link to part of the tutorial. An example with a for statement at the
beginning is good. I am not saying that it needs to be replaced with something.
The above example reads: "A list comprehension consists of brackets containing
an expression followed by a for clause, then zero or more for or if clauses".
________________________________
def transpose1_3_1 (a: list) -> list:
"" "Transpose matrix version 1.3.1" ""
max_j = len (max (a))
return [
[row [j] if j <len (row)
else 0 for row in a]
for j in range (max_j)]
_______________________________
Here a list comprehension consists of brackets containing an expression
followed by a if clause, then else and for clause in end.
It is clear that the above is written inaccurately (i.e. it can be corrected).
I think it's a good idea to add a similar example with an if statement at the
beginning.
At the end it says: “In the real world, you should prefer built-in functions to
complex flow statements. The zip () function would do a great job for this use
case".
It's good that this is said here about this function. I agree with the first
sentence. Disagree that zip () function would do a great job for this use case
(Transpose).
The examples in the tutorial only demonstrate the possibilities, they should be
simple, I understand. But, they cannot be used to solve a problem with a small
change in the value of variables, and this can be done very simply. The zip ()
function not only performed the transpose slower than even the first function,
but it also cannot execute it if the argument values change slightly. She only
repeated what could only work in this particular case.
It's good if the algorithms work more efficiently. It's not okay to use slow
algorithms. And it would be nice if programmers, reading the tutorial, would
write fast algorithms.
I already know about timeit. Thank. I have calculated the arithmetic mean for
many cases. The results were stable.
I wish you good.
----------
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue41590>
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