how to increment the iterator from inside for loop in python 3?

Question

for i in range (0, 81):     output = send command     while True:         last_byte = last_byte - offset     if last_byte > offset:        output = send command        i+     else:         output = send command         i+         break 

I want to increase the iterator every time the send command is executed. Right now it only increases by one when the for loop is executed. Please advise

for i in range(0,10):     print(i)     i +=2     print("increased i", i) 

I ran this code and it produced out from 0 to 9. I was expecting it would increase the iterator by 2.

Answer 1

Save a copy of the iterator as a named object. Then you can skip ahead if you want to.

>>> myiter = iter(range(0, 10)) >>> for i in myiter:     print(i)     next(myiter, None) ... 0 2 4 6 8 

Answer 2

You can't do that inside a for loop. Because every time that the loop gets restarted it reassign the variable i (even after you change it inside the loop) and every time you just increase the reassigned variable. If you want to do such thing you better to use a while loop and increase the throwaway variable manually.

>>> i=0 >>> while i< 10 : ...     print(i) ...     i +=2 ...     print("increased i", i) ...  0 ('increased i', 2) 2 ('increased i', 4) 4 ('increased i', 6) 6 ('increased i', 8) 8 ('increased i', 10) 

Beside that, if you want to increase the variable on a period rather than based some particular condition, you can use a proper slicers to slice the iterable in which you're looping over.

For instance if you have an iterator you can use itertools.islice() if you have a list you can simply use steps while indexing (my_list[start:end:step]).