Python for loop help

[Hugs12343]

Hi all

 

Here is my code

for i in range(0, 5):
  if i == 3:
    # here i want to change i to another number
    print(i)
  else:
    print(i)

I know it sounds useless but this is as simple as I could get it for a bigger program

 

How can I change the var i in the for loop?

 

If I type on line 3

i = 5

it will say that i is undefined because it is only a local variable

 

So how can I change the var i in the for loop?

Edited March 19, 2018 by Hugs12343
Error in code

[Streetguru]

4 minutes ago, Hugs12343 said:

 

Just define "i" before the for loop? like i = 0?

[Hugs12343]

Just now, Streetguru said:

Just define "i" before the for loop? like i = 0?

Tried that doesn't work

[tikker]

I'm not sure what you are doing, but that code should work if you fix the missing semicolon at the end of the first line.

[manikyath]

supposedly "i" should be usable anywhere within the loop..

 

let me try this out.. its gonna be something silly..

[Hugs12343]

Just now, tikker said:

missing semicolon at the end of the first line.

There's no semicolon. It's python

[tikker]

1 minute ago, Hugs12343 said:

There's no semicolon. It's python

Err, colon I meant:

 

for i in range(0, 5):
  if i == 3:
    # here i want to change i to another number
    i = 5
    print(i)
  else:
    print(i)

Works just fine. Are you by chance trying to access i somewhere else? The exact error message would be useful.

[manikyath]

5 minutes ago, tikker said:

Err, colon I meant:

 

for i in range(0, 5):
  if i == 3:
    # here i want to change i to another number
    i = 5
    print(i)
  else:
    print(i)

Works just fine.

can confirm.

 

EDIT: however, the value of i does not carry over outside the if statement

EDIT/EDIT: thats the purpose of a for loop isnt it? disregard..

 

what this does:

first round i = 0 => else, prints 0

second round i=1 => else, prints 1

third round, i=2 => else, prints 2

fourth round, i=3 => if, prints 5

fifth round, i=4 => prints 4

loop done.

[Hotseff]

49 minutes ago, Hugs12343 said:

Hi all

 

Here is my code

for i in range(0, 5):
  if i == 3:
    # here i want to change i to another number
    print(i)
  else:
    print(i)

I know it sounds useless but this is as simple as I could get it for a bigger program

 

How can I change the var i in the for loop?

 

If I type on line 3

i = 5

it will say that i is undefined because it is only a local variable

 

So how can I change the var i in the for loop?

 

class u():
    i = range(0,5)
for i in u.i:
    if(i == 3):
        i = 7
        print(i)
    else:
        print(i)

 

This works it and all you had to do is put variable i in a class to make it where you could change it.

[Hugs12343]

3 hours ago, Hotseff said:

 

class u():
    i = range(0,5)
for i in u.i:
    if(i == 3):
        i = 7
        print(i)
    else:
        print(i)

 

This works it and all you had to do is put variable i in a class to make it where you could change it.

I tried this. but it doesn't change the variable i in the for loop.

[straight_stewie]

2 hours ago, Hugs12343 said:

I tried this. but it doesn't change the variable i in the for loop.

Try this:

 

 

6 hours ago, tikker said:

Err, colon I meant:

 

for i in range(0, 5):
  if i == 3:
    # here i want to change i to another number
    i = 5
    print(i)
  else:
    print(i)

Works just fine. Are you by chance trying to access i somewhere else? The exact error message would be useful.

 

 

[vorticalbox]

9 hours ago, Hugs12343 said:

I know it sounds useless but this is as simple as I could get it for a bigger program

What is the bigger problem maybe we can help with that.

[tikker]

14 hours ago, Hugs12343 said:

I tried this. but it doesn't change the variable i in the for loop.

What is it that you are trying to change about it?

Let me elaborate on my earlier snippet. I've removed the redundant double print statemement. Take a look at this example (code below as well): https://repl.it/repls/BleakGrizzledPolygon

#Show the values that will be iterated over. list(...) is needed since in Python3 range is a generator, like  xrange in Python2.
i = list(range(0, 5))
print(i)

# Loop over them.
for i in range(0, 5):
  print('Iteration ', i)
  if i == 3:
    # Change i to hold the value 5 temporarily.
    i = 5
    print('The value of i will now be', i, 'for the rest of the loop.')
  print('The value of i is', i, '\n')

 

The range function will, as its name implies, generate a range of numbers between a given start and end. By definition the value i will take the next value in the range at the start of each iteration. Once you assign a new value to it, it will keep that value for the rest of the loop, or until it is changed again. Once the next iteration starts however, i will be (re)set to its intended value: the next one in the range.

 

9 hours ago, vorticalbox said:

What is the bigger problem maybe we can help with that.

This may help us give more concrete help.