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:

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:

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.

print(i, i + 15 + i // 3) - is this what you are looking for? No ifs needed — go2nirvana
– go2nirvana, Commented Dec 3, 2020 at 11:55

IoaTzimas · Accepted Answer · 2020-12-03 12:35:58Z

3

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

edited Dec 3, 2020 at 12:35

answered Dec 3, 2020 at 11:56

IoaTzimas

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4 Comments

Link_tester Over a year ago

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 Over a year ago

Sure, do you want to always keep groups of 3, no matter the start of the range?

Link_tester Over a year ago

Yes, exactly. My steps are 3 but start is from 4 up tp 10 (for example). Thanks in advance.

IoaTzimas Over a year ago

Code updated. Just add (i-k)//3 where k is the start of the range

host php · Accepted Answer · 2020-12-03 12:02:30Z

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

answered Dec 3, 2020 at 12:02

host php

312 bronze badges

Comments

Dmitry Kulazhenko · Accepted Answer · 2020-12-03 12:02:50Z

1

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)

answered Dec 3, 2020 at 12:02

Dmitry Kulazhenko

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