Source code for pyproximal.proximal.Box

import numpy as np
from pyproximal.ProxOperator import _check_tau
from pyproximal import ProxOperator
from pyproximal.projection import BoxProj

[docs]class Box(ProxOperator): r"""Box proximal operator. Proximal operator of a Box: :math:`\operatorname{Box}_{[l, u]} = \{ x: l \leq x\leq u \}`. Parameters ---------- lower : :obj:`float` or :obj:`np.ndarray`, optional Lower bound upper : :obj:`float` or :obj:`np.ndarray`, optional Upper bound Notes ----- As the Box is an indicator function, the proximal operator corresponds to its orthogonal projection (see :class:`pyproximal.projection.BoxProj` for details. """ def __init__(self, lower=-np.inf, upper=np.inf): super().__init__(None, False) self.lower = lower self.upper = upper = BoxProj(self.lower , self.upper) def __call__(self, x): return np.all((x > self.lower) & (x < self.upper)).astype(x.dtype) @_check_tau def prox(self, x, tau): return