round_half_up

round_half_up(value: int | str, precision: float = 0) → float[source]

Provides the "round to given precision with ties going away from zero" behaviour that was the default Python2 rounding behavior.

The behaviour of the "round" built-in changed from Python 2 to Python 3.

In Python 2, round() was rounding to the given precision, with ties going away from 0. For example:

[round(a) for a in [-2.5, -1.5, -0.5, 0.5, 1.5, 2.5]] == [-3.0, -2.0, -1.0, 1.0, 2.0, 3.0]

In Python 3, round() become "Banker's rounding", rounding to the nearest even integer, following the IEEE 754 standard for floating-point arithmetic. For example:

>>> [round(a) for a in [-2.5, -1.5, -0.5, 0.5, 1.5, 2.5]]
[-2, -2, 0, 0, 2, 2]

Note: in this function and the underlying Python decimal module, "round half up" refers to "round half away from zero" behaviour, rather than rounding half up to positive infinity.

Parameters:

  • value -- Un-rounded value

  • precision -- Precision of un-rounded value to consider when rounding

Returns:

rounded value to given precision with ties going away from 0