Class _Edge_integer

lib/matplotlib/ticker.py:2063–2108

Helper for `.MaxNLocator`, `.MultipleLocator`, etc. Take floating-point precision limitations into account when calculating tick locations as integer multiples of a step.

class _Edge_integer:
    """
    Helper for `.MaxNLocator`, `.MultipleLocator`, etc.

    Take floating-point precision limitations into account when calculating
    tick locations as integer multiples of a step.
    """

    def __init__(self, step, offset):
        """
        Parameters
        ----------
        step : float > 0
            Interval between ticks.
        offset : float
            Offset subtracted from the data limits prior to calculating tick
            locations.
        """
        if step <= 0:
            raise ValueError("'step' must be positive")
        self.step = step
        self._offset = abs(offset)

    def closeto(self, ms, edge):
        # Allow more slop when the offset is large compared to the step.
        if self._offset > 0:
            digits = np.log10(self._offset / self.step)
            tol = max(1e-10, 10 ** (digits - 12))
            tol = min(0.4999, tol)
        else:
            tol = 1e-10
        return abs(ms - edge) < tol

    def le(self, x):
        """Return the largest n: n*step <= x."""
        d, m = divmod(x, self.step)
        if self.closeto(m / self.step, 1):
            return d + 1
        return d

    def ge(self, x):
        """Return the smallest n: n*step >= x."""
        d, m = divmod(x, self.step)
        if self.closeto(m / self.step, 0):
            return d
        return d + 1


class MaxNLocator(Locator):