How to insert an if condition in a for loop in python

Question

I want to do a for loop and explain it here by simple print function. I want change the data printed after a fixed value. Let's regard this code:

for i in range (7):
 print (i, i+15, i+1)

it gives me:

0 15 1
1 16 2
2 17 3
3 18 4
4 19 5
5 20 6
6 21 7

But I want to add 1 to the printed values of the second row after each 3 interation. I mean from the first to third iteration, I want the same results as printed above. But from third to sixth I want to add 1 to i+15 (printing i+16 rather than i+15). Then again after the sixth row, I want to add 1 to i+16 (printing i+17 rather than i+16 or i+15). I mean I want to have this one:

0 15 1
1 16 2
2 17 3
3 19 4
4 20 5
5 21 6
6 23 7

How can I make my i in the function to e such a thing? Itried the following but it gives another thing:

for i in range (7):
 if i % 3 == 0:
 print (i, i+15+1, i+1)
 else:
 print (i, i+15, i+1)

I do appreciate any help in advance.

• go2nirvana: print(i, i + 15 + i // 3) - is this what you are looking for? No ifs needed

Answer 1

Try this:

for i in range (7):
 print (i, i//3+i+15, i+1)
0 15 1
1 16 2
2 17 3
3 19 4
4 20 5
5 21 6
6 23 7

For ranges that don't start from 0, to keep the same logic (increment every 3 iterations) you can do the following:

for i in range (4,15):
 print (i, (i-4)//3+i+15, i+1)
4 19 5
5 20 6
6 21 7
7 23 8
8 24 9
9 25 10
10 27 11
11 28 12
12 29 13
13 31 14
14 32 15

• Link_tester: Dear @IoaTzimas Thanks for you helpful solution. I tried to do it for ranges which does not start from 0, but it does not work out for them. Can you please tell me how I can extend your solution to other ranges (for example range (4, 10))? I do appreciate your help.
• IoaTzimas: Sure, do you want to always keep groups of 3, no matter the start of the range?
• Link_tester: Yes, exactly. My steps are 3 but start is from 4 up tp 10 (for example). Thanks in advance.
• IoaTzimas: Code updated. Just add (i-k)//3 where k is the start of the range

Answer 2

print("Hello world")
starting = 14;
for i in range (7):
 
 if(i %3==0):
 starting=starting+1
 print (i, i+starting, i+1)

Just added if condition to detect

Answer 3

You can do smth like this:

for i in range(7):
 print(i, i + 15 + i // 3, i + 1)

or, if you want, you can save this delta to variable.

inc = 0
for i in range(7):
 if i > 0 and i % 3 == 0:
 inc += 1
 print(i, i + 15 + inc, i + 1)

I think more pythonic way of 2nd variant:

inc = 0
for i in range(7):
 if i > 0:
 inc += i % 3 == 0
 print(i, i + 15 + inc, i + 1)