CODEWITHSUNDEEP
python
hello
hello

Reputation: 9

I am trying to remove the integer 0 from my list and appending it to the end (moving all the zeros to the end)

hello i am a beginner to python and I need help with this issue I have to write an algorithm that takes an array and moves all of the zeros to the end, preserving the order of the other elements.

move_zeros([1, 0, 1, 2, 0, 1, 3]) would return returns [1, 1, 2, 1, 3, 0, 0]

def move_zeros(array):
zeroCount = 0
length = len(array)
for i in range(length):
    if array[i] == "0":
        zeroCount += 1
array.remove(0)
for i in range(zeroCount):
    
    array.append("0")
    
        
return array

Upvotes: 0

Views: 314

Answers (3)

blunova
blunova

Reputation: 2532

To me, the way you are trying to code this is a little bit too complicated so, since we are using Python, I would try to be as pythonic as possible.

I would do something like this:

  1. Create a list with no zeros.
  2. Count the number of zeros in your original list
  3. Create a list of zeros where this list length is given by point 2.
  4. Append the list of zeros to the list with no zeros.
def move_zeros(array):
    
    array_no_zeros = [i for i in array if i != 0]
    zero_count = array.count(0)
    zeros_list = [0] * zero_count
    return array_no_zeros + zeros_list

result = move_zeros([1, 0, 1, 2, 0, 1, 3])
>>> [1, 1, 2, 1, 3, 0, 0]

Upvotes: 0

Emopusta
Emopusta

Reputation: 90

def move_zeros(array):
    zeroCount = 0
    
    for i in range(len(array)):
        if array[i] == 0:
            zeroCount += 1
            
    for i in range(zeroCount):#you have to call array.remove(0) zeroCount times to remove all zeros
        array.remove(0)
            
    for i in range(zeroCount):
        array.append(0)
        
    return array

array = [1,0,1,2,1,0,3]

print(move_zeros(array))

Upvotes: 0

Samwise
Samwise

Reputation: 71454

The first two problems that jump out are that the indentation is wrong, and that your code is looking for "0", not 0. Let's fix those before we start debugging:

def move_zeros(array):
    zeroCount = 0
    length = len(array)
    for i in range(length):
        if array[i] == 0:
            zeroCount += 1
    array.remove(0)
    for i in range(zeroCount):
        
        array.append(0)
    return array

That's not enough to make this work, though:

>>> move_zeros([1, 0, 1, 2, 0, 1, 3])
[1, 1, 2, 0, 1, 3, 0, 0]

Looks like we're only removing one zero, but we're appending two! That must be because remove only removes one instance. An easy fix for that is to do it in a loop:

    for _ in range(zeroCount):
        array.remove(0)

which now gives us the right answer:

>>> move_zeros([1, 0, 1, 2, 0, 1, 3])
[1, 1, 2, 1, 3, 0, 0]

And we can make the function a little simpler by replacing the for i in range(length) thing with a call to array.count():

def move_zeros(array):
    zero_count = array.count(0)
    for _ in range(zero_count):
        array.remove(0)
    for _ in range(zero_count):
        array.append(0)
    return array

Something to watch out for is that this function doesn't just return a list with the zeroes moved, it moves them in the original as well. If you wanted to avoid that, a better approach would be to build a brand new list, e.g.:

def move_zeros(array):
    return [i for i in array if i != 0] + [i for i in array if i == 0]

Upvotes: 1

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