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Numbers

Overview

Section titled “Overview”

Numbers are one family: there is no separate stored int and float type. int, float, and number are three views of the same value, decided by the value itself.

int, float, number

Section titled “int, float, number”
  • int: a whole numeric value (no decimal part)
  • float: a value with a decimal part
  • number: either of the above

The label follows the current value, not how you wrote it:

type(5)     # int
type(0.6)   # float
type(4.0)   # int  (whole value)
type(10 / 2) # int  (10 / 2 is 5.0)
type(10 / 3) # float

Not Python’s model

In Python type(4.0) is float because the literal was written as a float. Here it is int because the value is whole. The number itself is identical, only the label differs.

Checking a number

Section titled “Checking a number”
isinstance(x, int)          # True if x is whole
isinstance(x, float)        # True if x has a decimal part
isinstance(x, int | float)  # True for either numeric category
isinstance(x, "number")     # True for any number
x % 1 == 0                  # True if x is whole

Use isinstance(x, "number") when you only care that a value is numeric at all, and int(x) to chop a value to a whole number (int(3.7) is 3).

Precision

Section titled “Precision”

Decimal numbers use standard floating-point arithmetic, so tiny rounding can show up:

0.1 + 0.2  # 0.30000000000000004, not exactly 0.3

This is normal for calculated decimal values. Use isclose() when you mean close enough rather than bit-for-bit equality:

if isclose(0.1 + 0.2, 0.3):
  print("equal for this calculation")

The default rel_tol handles ordinary rounding relative to the size of the values. Use abs_tol when your accepted difference has a real gameplay meaning. For example, this treats a Rover within half a meter on both axes as being at the target:

target_x = 100
target_y = 40
pos = self.nav.get_position()
if isclose(pos.x, target_x, abs_tol=0.5) and isclose(pos.y, target_y, abs_tol=0.5):
  print("at target")

Choose the tolerance from what the value represents, such as meters, Wh, or a 0-1 level. Knowing only that a value is floating-point does not determine the right gameplay tolerance.

See also

Section titled “See also”