How to Check if a Float Represents an Integer in Python?

Determining Integerity of Float Values

In this code snippet, you're seeking the largest cube root that is a whole number, less than 12,000:

processing = True
n = 12000
while processing:
    n -= 1
    if n ** (1/3) == #checks to see if this has decimals or not

To verify if a float value is an integer, you can utilize the float.is_integer() method:

>>> (1.0).is_integer()
True
>>> (1.555).is_integer()
False

Note that in Python 2, 1/3 results in 0 due to floor division for integer operands, and floating-point arithmetic can be inexact. Adjusting the loop with this in mind:

for n in range(12000, -1, -1):
    if (n ** (1.0/3)).is_integer():
        print n

We obtain the expected results:

27
8
1
0

However, due to the imprecision of floating-point arithmetic, numbers higher than 3 cubed (including 10648) are omitted. To address this, you can check for numbers close to the whole number instead:

import math

for n in range(12000, -1, -1):
    if math.isclose((n ** (1.0/3)), round(n ** (1.0/3))):
        print n

This variation outputs:

10648
27
8
1
0

For Python 3.5 and later, you can utilize the math.isclose() function to check if a floating-point value is within a customizable margin.

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