Range, Break, and Continue

wow

very interesting!

Thank you so much for breaking this topic down for me! Love how you helped me to understand it!!!!!

It’s a good intro to this important topic. However, it should be expanded to show some good and practical examples - eg. deep-dive on some edge cases and show how-to approach on those questions.

Great work !! easy to understand and follow.

Your explanation is so amazing. just wow Darren

Thanks, very nice!

its good explanation ,but you should include some advanced concept with for loop

Yes this is a great intro, but I could sure use more depth to the for loop using compounding logic on an intermediate level

Very good tutorial Darren; thank you so much!

When I started this video course I am thinking “I already know about for loops do I need to watch this video” on other side I was telling to myself Real Python will try to include something new. I am right, I didn’t know about “else” part in for loops. I learned one new thing today.

@Darren,

Thank you for this brief tutorial. Is there a way to use the range() function with floats in the context of for-loops? I’ve checked the official documentation and it says that all the parameters passed to this function must be ints. But, I can imagine cases where iterating over a range of floats using a float value as a stride / step could be necessary, e.g.:

for i in range(10.5, 20.5, 0.5)

Is there a concise workaround for this approach?

Cheers.

@DoubleA If you don’t mind using NumPy, you can take advantage of its arange() function:

>>> np.arange(10.5, 20.5, 0.5)
array([10.5, 11. , 11.5, 12. , 12.5, 13. , 13.5, 14. , 14.5, 15. , 15.5,
       16. , 16.5, 17. , 17.5, 18. , 18.5, 19. , 19.5, 20. ])

It also comes with the linspace() function, which returns evenly spaced numbers. However, you’d have to convert your step into the number of intervals:

>>> import numpy as np
>>> np.linspace(10.5, 20, int((20.5-10.5)/0.5))
array([10.5, 11. , 11.5, 12. , 12.5, 13. , 13.5, 14. , 14.5, 15. , 15.5,
       16. , 16.5, 17. , 17.5, 18. , 18.5, 19. , 19.5, 20. ])

To achieve the desired effect in pure Python, you can whip up a custom function:

>>> def frange(start, stop, step):
...     while start < stop:
...         yield start
...         start += step
... 
>>> list(frange(10.5, 20.5, 0.5))
[10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 1
7.0, 17.5, 18.0, 18.5, 19.0, 19.5, 20.0]

@Bartosz, thank you:)

The custom function seems to make more sense to me at this stage. Actually, it is quite concise and clear. I wasn’t aware of the yield keyword in the context of generator functions though. Thanks for the tip!

BTW, for those who want to explore more –> the official documentation contains some useful information concerning this topic too.

My #1 takeaway was the understanding of Break and Continue! Break STOPS the loop when a given condition is found, whereas Continue SKIPS OVER items that meet the given condition but otherwise continues the loop. Thank you!

Dan, your style is perfect for teaching, not to say that the other authors are not good, because they are. However, I find myself learning more from your tutorials. Really Wish you could do a whole series from start to end on learning Python. Keep up the great work.

Darren,

what is the purpose of else in the for loops? If the ‘for’ is executing successfully why is it that ‘else’ is also executing?

@nnpdba The else code block in a for-loop will run when the loop terminates normally:

>>> for i in range(10):
...     print(i)
... else:
...     print("We've looped through all numbers")
... 
0
1
2
3
4
5
6
7
8
9
We've looped through all numbers

Otherwise, when you break out of the loop early, then the else clause won’t run:

>>> for i in range(10):
...     if i == 5:
...         break  # Break out of the loop early
...     print(i)
... else:
...     print("We've looped through all numbers")
... 
0
1
2
3
4

Found that I don’t use range in variable line instead I used it in the statement. Thanks for this alternate scripting technique.