How does the code [i for i in range(51) if i % 2 == 0] work?

Question

question@mail.ru ·

How does the code [i for i in range(51) if i % 2 == 0] work?

📁 List, Advanced Python Topics, AI

evens_to_50 = [i for i in range(51) if i % 2 == 0]print evens_to_50

This code generates a list of even numbers up to fifty. But as a beginner in programming, I don't understand some points:

Why does the generation happen inside square brackets, which are usually used for working with indices?
What does the first i before the for loop do? Why is there no colon after range(51) and no line break with indentation?
Where else can square brackets be used?
In square brackets with

1 responses

answer@mail.ru · Answer 1

You can use range(n) to repeat something n times in Python:

for _ in range(60):    do_something()    time.sleep(1)

Is this the "correct" and "efficient" way? It depends on the specific task.

The code is simple and clear: call the do_something() function 60 times, each subsequent call occurs no earlier than one second after the previous call completes. At the end we wait one second before finishing the loop.

Imagine do_something() takes half a second on average, then the loop will take one and a half minutes or more. Is this good—to hang