CODEWITHSUNDEEP
python
user3367018
user3367018

Reputation: 33

I need to write this same program but with a while loop instead of a for loop

Here's the original code:

def scrollList(myList):
    negativeIndices = []
    for i in range(0,len(myList)):
        if myList[i] < 0:
            negativeIndices.append(i)
    return negativeIndices

and here's what i've got so far:

def scrollList2(myList):
    negativeIndices = []
    needMoreNumbers = True
    while (needMoreNumbers):
        if myList[i] < 0:
            negativeIndices.append(i)
        n = n-1
        if (n<1):
            needMoreNumbers = False
            return negativeIndices

Right now I'm getting the error "global name 'i' is not defined which I know it's not but I don't know how to go about defining 'i' without a for loop. Thanks

Upvotes: 0

Views: 112

Answers (4)

Migol
Migol

Reputation: 8448

Well, you can try manually doing indexation.

def scrollList2(myList):
  negativeIndices = []
  index = 0
  while (index < len(myList)):
    if myList[index] < 0:
      negativeIndices.append(index)
    index+=1
  return negativeIndices

Upvotes: 0

vish
vish

Reputation: 1056

the pythonic answer is 

indices = [i for i,n in enumerate(mylist) if n<0]

or use () instead of [] for a generator (to dynamically generate them one by one)

Upvotes: 0

wheaties
wheaties

Reputation: 35970

The reason you're getting a global error on i is that you've not defined it anywhere. You have to define what you use. You've also not defined the variable n. After fixing i you'll get an error on that too.

So, define n in front of the while loop like so

n = len(myList)
while(needsMoreStuff):

and change the reference to i to be

if myList[n] < 0:
  negativeIndices.append(n)

should suffice to fix your error.

Edit:

Suggested a different looping construct and then edited it to be more in keeping with the question. Problem is an undeclared variable.

Upvotes: 1

Paulo Bu
Paulo Bu

Reputation: 29794

Just simulate it with a counter variable:

def scrollList2(myList):
    negativeIndices = []
    counter = 0
    while (counter < len(myList)):
        if myList[counter] < 0:
            negativeIndices.append(counter)
        counter += 1

    return negativeIndices

Upvotes: 0

Related Questions