I need to exclude 0.0 in some cases of my function.

I've been making a function where a number x is outputted as a string of numbers that decrease by 0.5 as long as x is positive.

(eg. x = 3.3; output = ''3.3, 2.8, 2.3, 1.8, 1.3, 0.8, 0.3')

Here is the code.

# reductions.py

## Receives a number: x
## Outputs a string of numbers that starts with the number and
## decreases by 0.5 as long as the x value is positive
## NOTE: If it receives a negative number, it returns a 0
## Example 1:
##    Input: 4
##    Output: '4, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0'
## Example 2:
##    Input: -3
##    Output: '0'
## WARNING:
##    do not include a comma and space at the end of the string

import math

# Define generator function
def reductions_gen_helper(x):
    """ Generates a string starting with x that decreases by 0.5 as long as
x is positive """

    # Calculate string
    while x >= 0:
        yield x # Keep the values
        str(x).strip("")
        x -= 0.5
        x = math.ceil(x*10)/10

# Define used function
def reductions(x):
    """ Returns a string starting with that x that decreases by 0.5 as long as
x is positive """

    # Check for negative input
    if x <= 0:
        return('0')

    else:
        return ", ".join(str(x) for x in reductions_gen_helper(x))

And here is the unit test for it.

# Testreductions.py

# Import Statements
import unittest
import reductions

class KnownValues(unittest.TestCase):
    # Formula for unittest method is:
    # test_functionName_testDescription

    def test_reductionsForEvenValues(self):
        # Capture the results of the function
        result = reductions.reductions(4)
        # Check for expected output
        self.assertEqual('4, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0',
                         result)

    def test_reductionsForOddFloatValues(self):
        # Capture the results of the function
        result = reductions.reductions(3.3)
        # Check for expected output
        self.assertEqual('3.3, 2.8, 2.3, 1.8, 1.3, 0.8, 0.3',
                         result)

    def test_reductionsForPositiveOddValues(self):
        # Capture the results of the function
        result = reductions.reductions(5)
        # Check for expected output
        self.assertEqual('5, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0',
                         result)

    def test_reductionsForPositiveFloatValues(self):
        # Capture the results of the function
        result = reductions.reductions(4.4)
        # Check for expected output
        self.assertEqual('4.4, 3.9, 3.4, 2.9, 2.4, 1.9, 1.4, 0.9, 0.4',
                         result)

    def test_reductionsForNegativeNumber(self):
        # Capture the results of the function
        result = reductions.reductions(-3)
        # Check for expected output
        self.assertEqual('0', result)

    def test_reductionsForZero(self):
        # Capture the results of the function
        result = reductions.reductions(0)
        # Check for expected output
        self.assertEqual('0', result)
# Run the tests
if __name__ == '__main__':
    unittest.main()

When I run the tests, I get these errors.

  ..FF..
======================================================================
FAIL: test_reductionsForOddFloatValues (__main__.KnownValues)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "M:\Digital Media\Winikka\Programming 1\_Student Folders\Period4\let147\Python Challenge Projects\WhileLoopsChallengeSpring2016-master\TestReductions.py", line 23, in test_reductionsForOddFloatValues
    result)
AssertionError: '3.3, 2.8, 2.3, 1.8, 1.3, 0.8, 0.3' != '3.3, 2.8, 2.3, 1.8, 1.3, 0.8, 0.4, 0.0'
- 3.3, 2.8, 2.3, 1.8, 1.3, 0.8, 0.3
?                                 ^
+ 3.3, 2.8, 2.3, 1.8, 1.3, 0.8, 0.4, 0.0
?                                 ^^^^^^


======================================================================
FAIL: test_reductionsForPositiveFloatValues (__main__.KnownValues)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "M:\Digital Media\Winikka\Programming 1\_Student Folders\Period4\let147\Python Challenge Projects\WhileLoopsChallengeSpring2016-master\TestReductions.py", line 37, in test_reductionsForPositiveFloatValues
    result)
AssertionError: '4.4, 3.9, 3.4, 2.9, 2.4, 1.9, 1.4, 0.9, 0.4' != '4.4, 3.9, 3.4, 2.9, 2.4, 1.9, 1.4, 0.9, 0.4, 0.0'
- 4.4, 3.9, 3.4, 2.9, 2.4, 1.9, 1.4, 0.9, 0.4
+ 4.4, 3.9, 3.4, 2.9, 2.4, 1.9, 1.4, 0.9, 0.4, 0.0
?                                            +++++


----------------------------------------------------------------------
Ran 6 tests in 0.062s

FAILED (failures=2)

Is there any way to fix this?