def bounded_mean(mean_x, samples, xmin, xmax, wts=None):
from mystic.math.measures import impose_mean, impose_spread
from mystic.math.measures import spread, mean
from numpy import asarray
a = impose_mean(mean_x, samples, wts)
if min(a) < xmin: # maintain the bound
#print "violate lo(a)"
s = spread(a) - 2*(xmin - min(a)) #XXX: needs compensation (as below) ?
a = impose_mean(mean_x, impose_spread(s, samples, wts), wts)
if max(a) > xmax: # maintain the bound
#print "violate hi(a)"
s = spread(a) + 2*(xmax - max(a)) #XXX: needs compensation (as below) ?
a = impose_mean(mean_x, impose_spread(s, samples, wts), wts)
return asarray(a)
def bounded_mean(mean_x, samples, xmin, xmax, wts=None):
from mystic.math.measures import impose_mean, impose_spread
from mystic.math.measures import spread, mean
from numpy import asarray
a = impose_mean(mean_x, samples, wts)
if min(a) < xmin: # maintain the bound
#print "violate lo(a)"
s = spread(a) - 2*(xmin - min(a)) #XXX: needs compensation (as below) ?
a = impose_mean(mean_x, impose_spread(s, samples, wts), wts)
if max(a) > xmax: # maintain the bound
#print "violate hi(a)"
s = spread(a) + 2*(xmax - max(a)) #XXX: needs compensation (as below) ?
a = impose_mean(mean_x, impose_spread(s, samples, wts), wts)
return asarray(a)
def test_constrain():
from mystic.math.measures import mean, spread
from mystic.math.measures import impose_mean, impose_spread
def mean_constraint(x, mean=0.0):
return impose_mean(mean, x)
def range_constraint(x, spread=1.0):
return impose_spread(spread, x)
@inner(inner=range_constraint, kwds={'spread': 5.0})
@inner(inner=mean_constraint, kwds={'mean': 5.0})
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from mystic.solvers import fmin_powell
from numpy import array
x = array([1, 2, 3, 4, 5])
y = fmin_powell(cost, x, constraints=constraints, disp=False)
assert mean(y) == 5.0
assert spread(y) == 5.0
assert almostEqual(cost(y), 4 * (5.0))
def test_inner_solver(nested, solver):
from mystic.monitors import Monitor
evalmon = Monitor()
stepmon = Monitor()
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
solver = solver(5)
lb, ub = [0, 0, 0, 0, 0], [100, 100, 100, 100, 100]
solver.SetRandomInitialPoints(lb, ub)
solver.SetConstraints(constraints)
solver.SetStrictRanges(lb, ub)
nested = nested(5, 4)
nested.SetEvaluationMonitor(evalmon)
nested.SetGenerationMonitor(stepmon)
nested.SetNestedSolver(solver)
nested.Solve(cost, disp=False)
y = nested.Solution()
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4 * (5.0), tol=1e-6)
def test_multi_liner(solver):
from mystic.monitors import Monitor
evalmon = Monitor()
stepmon = Monitor()
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
x = array([1, 2, 3, 4, 5])
solver = solver(len(x))
solver.SetInitialPoints(x)
solver.SetEvaluationMonitor(evalmon)
solver.SetGenerationMonitor(stepmon)
solver.SetConstraints(constraints)
solver.Solve(cost, disp=False)
y = solver.Solution()
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4 * (5.0), tol=1e-6)
def test_inner_solver(nested, solver):
from mystic.monitors import Monitor
evalmon = Monitor()
stepmon = Monitor()
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
solver = solver(5)
lb,ub = [0,0,0,0,0],[100,100,100,100,100]
solver.SetRandomInitialPoints(lb, ub)
solver.SetConstraints(constraints)
solver.SetStrictRanges(lb, ub)
nested = nested(5, 4)
nested.SetEvaluationMonitor(evalmon)
nested.SetGenerationMonitor(stepmon)
nested.SetNestedSolver(solver)
nested.Solve(cost, disp=False)
y = nested.Solution()
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4*(5.0), tol=1e-6)
def test_nested_solver(nested, solver):
from mystic.monitors import Monitor
evalmon = Monitor()
stepmon = Monitor()
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
nested = nested(5, 4)
nested.SetEvaluationMonitor(evalmon)
nested.SetGenerationMonitor(stepmon)
nested.SetConstraints(constraints)
nested.SetNestedSolver(solver)
nested.Solve(cost, disp=False)
y = nested.Solution()
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4*(5.0), tol=1e-6)
def test_multi_liner(solver):
from mystic.monitors import Monitor
evalmon = Monitor()
stepmon = Monitor()
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
x = array([1,2,3,4,5])
solver = solver(len(x))
solver.SetInitialPoints(x)
solver.SetEvaluationMonitor(evalmon)
solver.SetGenerationMonitor(stepmon)
solver.SetConstraints(constraints)
solver.Solve(cost, disp=False)
y = solver.Solution()
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4*(5.0), tol=1e-6)
def test_nested_solver(nested, solver):
from mystic.monitors import Monitor
evalmon = Monitor()
stepmon = Monitor()
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
nested = nested(5, 4)
nested.SetEvaluationMonitor(evalmon)
nested.SetGenerationMonitor(stepmon)
nested.SetConstraints(constraints)
nested.SetNestedSolver(solver)
nested.Solve(cost, disp=False)
y = nested.Solution()
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4 * (5.0), tol=1e-6)
def test_penalize():
from mystic.math.measures import mean, spread
def mean_constraint(x, target):
return mean(x) - target
def range_constraint(x, target):
return spread(x) - target
@quadratic_equality(condition=range_constraint, kwds={'target': 5.0})
@quadratic_equality(condition=mean_constraint, kwds={'target': 5.0})
def penalty(x):
return 0.0
def cost(x):
return abs(sum(x) - 5.0)
from mystic.solvers import fmin
from numpy import array
x = array([1, 2, 3, 4, 5])
y = fmin(cost, x, penalty=penalty, disp=False)
assert round(mean(y)) == 5.0
assert round(spread(y)) == 5.0
assert round(cost(y)) == 4 * (5.0)
def test_penalize():
from mystic.math.measures import mean, spread
def mean_constraint(x, target):
return mean(x) - target
def range_constraint(x, target):
return spread(x) - target
@quadratic_equality(condition=range_constraint, kwds={'target':5.0})
@quadratic_equality(condition=mean_constraint, kwds={'target':5.0})
def penalty(x):
return 0.0
def cost(x):
return abs(sum(x) - 5.0)
from mystic.solvers import fmin
from numpy import array
x = array([1,2,3,4,5])
y = fmin(cost, x, penalty=penalty, disp=False)
assert round(mean(y)) == 5.0
assert round(spread(y)) == 5.0
assert round(cost(y)) == 4*(5.0)
def test_constrain():
from mystic.math.measures import mean, spread
from mystic.math.measures import impose_mean, impose_spread
def mean_constraint(x, mean=0.0):
return impose_mean(mean, x)
def range_constraint(x, spread=1.0):
return impose_spread(spread, x)
@inner(inner=range_constraint, kwds={'spread':5.0})
@inner(inner=mean_constraint, kwds={'mean':5.0})
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from mystic.solvers import fmin_powell
from numpy import array
x = array([1,2,3,4,5])
y = fmin_powell(cost, x, constraints=constraints, disp=False)
assert mean(y) == 5.0
assert spread(y) == 5.0
assert almostEqual(cost(y), 4*(5.0))
def test_generate_constraint():
constraints = """
spread([x0, x1, x2]) = 10.0
mean([x0, x1, x2]) = 5.0"""
from mystic.math.measures import mean, spread
solv = generate_solvers(constraints)
assert almostEqual(mean(solv[0]([1, 2, 3])), 5.0)
assert almostEqual(spread(solv[1]([1, 2, 3])), 10.0)
constraint = generate_constraint(solv)
assert almostEqual(constraint([1, 2, 3]), [0.0, 5.0, 10.0], 1e-10)
def test_generate_constraint(): constraints = """ spread([x0, x1, x2]) = 10.0 mean([x0, x1, x2]) = 5.0""" from mystic.math.measures import mean, spread solv = generate_solvers(constraints) assert almostEqual(mean(solv[0]([1,2,3])), 5.0) assert almostEqual(spread(solv[1]([1,2,3])), 10.0) constraint = generate_constraint(solv) assert almostEqual(constraint([1,2,3]), [0.0,5.0,10.0], 1e-10)
def test_solve_constraint():
constraints = """
spread([x0,x1]) - 1.0 = mean([x0,x1])
mean([x0,x1,x2]) = x2"""
from mystic.math.measures import mean, spread
_constraints = solve(constraints)
solv = generate_solvers(_constraints)
constraint = generate_constraint(solv)
x = constraint([1.0, 2.0, 3.0])
assert all(x) == all([1.0, 5.0, 3.0])
assert mean(x) == x[2]
assert spread(x[:-1]) - 1.0 == mean(x[:-1])
def test_solve_constraint(): constraints = """ spread([x0,x1]) - 1.0 = mean([x0,x1]) mean([x0,x1,x2]) = x2""" from mystic.math.measures import mean, spread _constraints = solve(constraints) solv = generate_solvers(_constraints) constraint = generate_constraint(solv) x = constraint([1.0, 2.0, 3.0]) assert all(x) == all([1.0, 5.0, 3.0]) assert mean(x) == x[2] assert spread(x[:-1]) - 1.0 == mean(x[:-1])
def test_as_constraint():
from mystic.math.measures import mean, spread
def mean_constraint(x, target):
return mean(x) - target
def range_constraint(x, target):
return spread(x) - target
@quadratic_equality(condition=range_constraint, kwds={'target': 5.0})
@quadratic_equality(condition=mean_constraint, kwds={'target': 5.0})
def penalty(x):
return 0.0
ndim = 3
constraints = as_constraint(penalty) #, solver='fmin')
#XXX: this is expensive to evaluate, as there are nested optimizations
from numpy import arange
x = arange(ndim)
_x = constraints(x)
assert round(mean(_x)) == 5.0
assert round(spread(_x)) == 5.0
assert round(penalty(_x)) == 0.0
def cost(x):
return abs(sum(x) - 5.0)
npop = ndim * 3
from mystic.solvers import diffev
y = diffev(cost, x, npop, constraints=constraints, disp=False, gtol=10)
assert round(mean(y)) == 5.0
assert round(spread(y)) == 5.0
assert round(cost(y)) == 5.0 * (ndim - 1)
def test_with_mean_spread():
from mystic.math.measures import mean, spread, impose_mean, impose_spread
@with_spread(50.0)
@with_mean(5.0)
def constrained_squared(x):
return [i**2 for i in x]
from numpy import array
x = array([1, 2, 3, 4, 5])
y = impose_spread(50.0, impose_mean(5.0, [i**2 for i in x]))
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 50.0, tol=1e-15)
assert constrained_squared(x) == y
def test_as_constraint():
from mystic.math.measures import mean, spread
def mean_constraint(x, target):
return mean(x) - target
def range_constraint(x, target):
return spread(x) - target
@quadratic_equality(condition=range_constraint, kwds={'target':5.0})
@quadratic_equality(condition=mean_constraint, kwds={'target':5.0})
def penalty(x):
return 0.0
ndim = 3
constraints = as_constraint(penalty, solver='fmin')
#XXX: this is expensive to evaluate, as there are nested optimizations
from numpy import arange
x = arange(ndim)
_x = constraints(x)
assert round(mean(_x)) == 5.0
assert round(spread(_x)) == 5.0
assert round(penalty(_x)) == 0.0
def cost(x):
return abs(sum(x) - 5.0)
npop = ndim*3
from mystic.solvers import diffev
y = diffev(cost, x, npop, constraints=constraints, disp=False, gtol=10)
assert round(mean(y)) == 5.0
assert round(spread(y)) == 5.0
assert round(cost(y)) == 5.0*(ndim-1)
def test_with_mean_spread():
from mystic.math.measures import mean, spread, impose_mean, impose_spread
@with_spread(50.0)
@with_mean(5.0)
def constrained_squared(x):
return [i**2 for i in x]
from numpy import array
x = array([1,2,3,4,5])
y = impose_spread(50.0, impose_mean(5.0,[i**2 for i in x]))
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 50.0, tol=1e-15)
assert constrained_squared(x) == y
def test_one_liner(solver):
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
x = array([1,2,3,4,5])
y = solver(cost, x, constraints=constraints, disp=False)
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4*(5.0), tol=1e-6)
def test_one_liner(solver):
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraints(x):
return x
def cost(x):
return abs(sum(x) - 5.0)
from numpy import array
x = array([1,2,3,4,5])
y = solver(cost, x, constraints=constraints, disp=False)
assert almostEqual(mean(y), 5.0, tol=1e-15)
assert almostEqual(spread(y), 5.0, tol=1e-15)
assert almostEqual(cost(y), 4*(5.0), tol=1e-6)
def test_as_penalty():
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraint(x):
return x
penalty = as_penalty(constraint)
from numpy import array
x = array([1,2,3,4,5])
def cost(x):
return abs(sum(x) - 5.0)
from mystic.solvers import fmin
y = fmin(cost, x, penalty=penalty, disp=False)
assert round(mean(y)) == 5.0
assert round(spread(y)) == 5.0
assert round(cost(y)) == 4*(5.0)
def test_as_penalty():
from mystic.math.measures import mean, spread
@with_spread(5.0)
@with_mean(5.0)
def constraint(x):
return x
penalty = as_penalty(constraint)
from numpy import array
x = array([1,2,3,4,5])
def cost(x):
return abs(sum(x) - 5.0)
from mystic.solvers import fmin
y = fmin(cost, x, penalty=penalty, disp=False)
assert round(mean(y)) == 5.0
assert round(spread(y)) == 5.0
assert round(cost(y)) == 4*(5.0)
def graphical_distance(model, points, **kwds):
"""find the ``radius(x')`` that minimizes the graph between reality (data),
``y = G(x)``, and an approximating function, ``y' = F(x')``.
Args:
model (func): a model ``y' = F(x')`` that approximates reality ``y = G(x)``
points (mystic.math.legacydata.dataset): a dataset, defines ``y = G(x)``
ytol (float, default=0.0): maximum acceptable difference ``|y - F(x')|``.
xtol (float, default=0.0): maximum acceptable difference ``|x - x'|``.
cutoff (float, default=ytol): zero out distances less than cutoff.
hausdorff (bool, default=False): hausdorff ``norm``, where if given,
then ``ytol = |y - F(x')| + |x - x'|/norm``.
Returns:
the radius (the minimum distance ``x,G(x)`` to ``x',F(x')`` for each ``x``)
Notes:
*points* can be a ``mystic.math.legacydata.dataset`` or a list of
``mystic.math.legacydata.datapoint`` objects.
*xtol* defines the n-dimensional base of a pilar of height *ytol*,
centered at each point. The region inside the pilar defines the space
where a "valid" model must intersect. If *xtol* is not specified, then
the base of the pilar will be a dirac at ``x' = x``. This function
performs an optimization for each ``x`` to find an appropriate ``x'``.
*ytol* is a single value, while *xtol* is a single value or an iterable.
*cutoff* takes a float or a boolean, where ``cutoff=True`` will set the
value of *cutoff* to the default. Typically, the value of *cutoff* is
*ytol*, 0.0, or None. *hausdorff* can be False (e.g. ``norm = 1.0``),
True (e.g. ``norm = spread(x)``), or a list of points of ``len(x)``.
While *cutoff* and *ytol* are very tightly related, they play a distinct
role; *ytol* is used to set the optimization termination for an acceptable
``|y - F(x')|``, while *cutoff* is applied post-optimization.
If we are using the hausdorff norm, then *ytol* will set the optimization
termination for an acceptable ``|y - F(x')| + |x - x'|/norm``, where the
``x`` values are normalized by ``norm = hausdorff``.
""" #FIXME: update docs to show normalization in y
#NotImplemented:
#L = list of lipschitz constants, for use when lipschitz metric is desired
#constraints = constraints function for finding minimum distance
from mystic.math.legacydata import dataset
from numpy import asarray, sum, isfinite, zeros, seterr
from mystic.solvers import diffev2, fmin_powell
from mystic.monitors import Monitor, VerboseMonitor
# ensure target xe and ye is a dataset
target = dataset()
target.load(*_get_xy(points))
nyi = target.npts # y's are target.values
nxi = len(target.coords[-1]) # nxi = len(x) / len(y)
# NOTE: the constraints function is a function over a single xe,ye
# because each underlying optimization is over a single xe,ye.
# thus, we 'pass' on using constraints at this time...
constraints = None # default is no constraints
if 'constraints' in kwds: constraints = kwds.pop('constraints')
if not constraints: # if None (default), there are no constraints
constraints = lambda x: x
# get tolerance in y and wiggle room in x
ytol = kwds.pop('ytol', 0.0)
xtol = kwds.pop('xtol', 0.0) # default is to not allow 'wiggle room' in x
cutoff = ytol # default is to zero out distances less than tolerance
if 'cutoff' in kwds: cutoff = kwds.pop('cutoff')
if cutoff is True: cutoff = ytol
elif cutoff is False: cutoff = None
ipop = kwds.pop('ipop', min(20, 3*nxi)) #XXX: tune ipop?
imax = kwds.pop('imax', 1000) #XXX: tune imax?
# get range for the dataset (normalization for hausdorff distance)
hausdorff = kwds.pop('hausdorff', False)
if not hausdorff: # False, (), None, ...
ptp = [0.0]*nxi
yptp = 1.0
elif hausdorff is True:
from mystic.math.measures import spread
ptp = [spread(xi) for xi in zip(*target.coords)]
yptp = spread(target.values) #XXX: this can lead to bad bad things...
else:
try: #iterables
if len(hausdorff) < nxi+1:
hausdorff = list(hausdorff) + [0.0]*(nxi - len(hausdorff)) + [1.0]
ptp = hausdorff[:-1] # all the x
yptp = hausdorff[-1] # just the y
except TypeError: #non-iterables
ptp = [hausdorff]*nxi
yptp = hausdorff
#########################################################################
def radius(model, point, ytol=0.0, xtol=0.0, ipop=None, imax=None):
"""graphical distance between a single point x,y and a model F(x')"""
# given a single point x,y: find the radius = |y - F(x')| + delta
# radius is just a minimization over x' of |y - F(x')| + delta
# where we apply a constraints function (of box constraints) of
# |x - x'| <= xtol (for each i in x)
#
# if hausdorff = some iterable, delta = |x - x'|/hausdorff
# if hausdorff = True, delta = |x - x'|/spread(x); using the dataset range
# if hausdorff = False, delta = 0.0
#
# if ipop, then DE else Powell; ytol is used in VTR(ytol)
# and will terminate when cost <= ytol
x,y = _get_xy(point)
y = asarray(y)
# catch cases where yptp or y will cause issues in normalization
#if not isfinite(yptp): return 0.0 #FIXME: correct? shouldn't happen
#if yptp == 0: from numpy import inf; return inf #FIXME: this is bad
# build the cost function
if hausdorff: # distance in all directions
def cost(rv):
'''cost = |y - F(x')| + |x - x'| for each x,y (point in dataset)'''
_y = model(rv)
if not isfinite(_y): return abs(_y)
errs = seterr(invalid='ignore', divide='ignore') # turn off warning
z = abs((asarray(x) - rv)/ptp) # normalize by range
m = abs(y - _y)/yptp # normalize by range
seterr(invalid=errs['invalid'], divide=errs['divide']) # turn on warning
return m + sum(z[isfinite(z)])
else: # vertical distance only
def cost(rv):
'''cost = |y - F(x')| for each x,y (point in dataset)'''
return abs(y - model(rv))
if debug:
print("rv: %s" % str(x))
print("cost: %s" % cost(x))
# if xtol=0, radius is difference in x,y and x,F(x); skip the optimization
try:
if not imax or not max(xtol): #iterables
return cost(x)
except TypeError:
if not xtol: #non-iterables
return cost(x)
# set the range constraints
xtol = asarray(xtol)
bounds = list(zip( x - xtol, x + xtol ))
if debug:
print("lower: %s" % str(zip(*bounds)[0]))
print("upper: %s" % str(zip(*bounds)[1]))
# optimize where initially x' = x
stepmon = Monitor()
if debug: stepmon = VerboseMonitor(1)
#XXX: edit settings?
MINMAX = 1 #XXX: confirm MINMAX=1 is minimization
ftol = ytol
gtol = None # use VTRCOG
if ipop:
results = diffev2(cost, bounds, ipop, ftol=ftol, gtol=gtol, \
itermon = stepmon, maxiter=imax, bounds=bounds, \
full_output=1, disp=0, handler=False)
else:
results = fmin_powell(cost, x, ftol=ftol, gtol=gtol, \
itermon = stepmon, maxiter=imax, bounds=bounds, \
full_output=1, disp=0, handler=False)
#solved = results[0] # x'
func_opt = MINMAX * results[1] # cost(x')
if debug:
print("solved: %s" % results[0])
print("cost: %s" % func_opt)
# get the minimum distance |y - F(x')|
return func_opt
#return results[0], func_opt
#########################################################################
#XXX: better to do a single optimization rather than for each point ???
d = [radius(model, point, ytol, xtol, ipop, imax) for point in target]
return infeasibility(d, cutoff)
def __range(self): from mystic.math.measures import spread return spread(self.positions)
def __range(self): from mystic.math.measures import spread return spread(self.positions)
def range_constraint(x, target): return spread(x) - target
def range_constraint(x, target):
return spread(x) - target
def graphical_distance(model, points, **kwds):
"""find the radius(x') that minimizes the graph between reality, y = G(x),
and an approximating function, y' = F(x')
Inputs:
model = the model function, y' = F(x'), that approximates reality, y = G(x)
points = object of type 'datapoint' to validate against; defines y = G(x)
Additional Inputs:
ytol = maximum acceptable difference |y - F(x')|; a single value
xtol = maximum acceptable difference |x - x'|; an iterable or single value
cutoff = zero out distances less than cutoff; typically: ytol, 0.0, or None
hausdorff = norm; where if given, ytol = |y - F(x')| + |x - x'|/norm
Returns:
radius = minimum distance from x,G(x) to x',F(x') for each x
Notes:
xtol defines the n-dimensional base of a pilar of height ytol, centered at
each point. The region inside the pilar defines the space where a "valid"
model must intersect. If xtol is not specified, then the base of the pilar
will be a dirac at x' = x. This function performs an optimization for each
x to find an appropriate x'. While cutoff and ytol are very tightly related,
they play a distinct role; ytol is used to set the optimization termination
for an acceptable |y - F(x')|, while cutoff is applied post-optimization.
If we are using the hausdorff norm, then ytol will set the optimization
termination for an acceptable |y - F(x')| + |x - x'|/norm, where the x
values are normalized by norm = hausdorff.
""" #FIXME: update docs to show normalization in y
#NotImplemented:
#L = list of lipschitz constants, for use when lipschitz metric is desired
#constraints = constraints function for finding minimum distance
from mystic.math.legacydata import dataset
from numpy import asarray, sum, isfinite, zeros, seterr
from mystic.solvers import diffev2, fmin_powell
from mystic.monitors import Monitor, VerboseMonitor
# ensure target xe and ye is a dataset
target = dataset()
target.load(*_get_xy(points))
nyi = target.npts # y's are target.values
nxi = len(target.coords[-1]) # nxi = len(x) / len(y)
# NOTE: the constraints function is a function over a single xe,ye
# because each underlying optimization is over a single xe,ye.
# thus, we 'pass' on using constraints at this time...
constraints = None # default is no constraints
if 'constraints' in kwds: constraints = kwds.pop('constraints')
if not constraints: # if None (default), there are no constraints
constraints = lambda x: x
# get tolerance in y and wiggle room in x
ytol = kwds.pop('ytol', 0.0)
xtol = kwds.pop('xtol', 0.0) # default is to not allow 'wiggle room' in x
cutoff = ytol # default is to zero out distances less than tolerance
if 'cutoff' in kwds: cutoff = kwds.pop('cutoff')
if cutoff is True: cutoff = ytol
elif cutoff is False: cutoff = None
ipop = kwds.pop('ipop', min(20, 3*nxi)) #XXX: tune ipop?
imax = kwds.pop('imax', 1000) #XXX: tune imax?
# get range for the dataset (normalization for hausdorff distance)
hausdorff = kwds.pop('hausdorff', False)
if not hausdorff: # False, (), None, ...
ptp = [0.0]*nxi
yptp = 1.0
elif hausdorff is True:
from mystic.math.measures import spread
ptp = [spread(xi) for xi in zip(*target.coords)]
yptp = spread(target.values) #XXX: this can lead to bad bad things...
else:
try: #iterables
if len(hausdorff) < nxi+1:
hausdorff = list(hausdorff) + [0.0]*(nxi - len(hausdorff)) + [1.0]
ptp = hausdorff[:-1] # all the x
yptp = hausdorff[-1] # just the y
except TypeError: #non-iterables
ptp = [hausdorff]*nxi
yptp = hausdorff
#########################################################################
def radius(model, point, ytol=0.0, xtol=0.0, ipop=None, imax=None):
"""graphical distance between a single point x,y and a model F(x')"""
# given a single point x,y: find the radius = |y - F(x')| + delta
# radius is just a minimization over x' of |y - F(x')| + delta
# where we apply a constraints function (of box constraints) of
# |x - x'| <= xtol (for each i in x)
#
# if hausdorff = some iterable, delta = |x - x'|/hausdorff
# if hausdorff = True, delta = |x - x'|/spread(x); using the dataset range
# if hausdorff = False, delta = 0.0
#
# if ipop, then DE else Powell; ytol is used in VTR(ytol)
# and will terminate when cost <= ytol
x,y = _get_xy(point)
y = asarray(y)
# catch cases where yptp or y will cause issues in normalization
#if not isfinite(yptp): return 0.0 #FIXME: correct? shouldn't happen
#if yptp == 0: from numpy import inf; return inf #FIXME: this is bad
# build the cost function
if hausdorff: # distance in all directions
def cost(rv):
'''cost = |y - F(x')| + |x - x'| for each x,y (point in dataset)'''
_y = model(rv)
if not isfinite(_y): return abs(_y)
errs = seterr(invalid='ignore', divide='ignore') # turn off warning
z = abs((asarray(x) - rv)/ptp) # normalize by range
m = abs(y - _y)/yptp # normalize by range
seterr(invalid=errs['invalid'], divide=errs['divide']) # turn on warning
return m + sum(z[isfinite(z)])
else: # vertical distance only
def cost(rv):
'''cost = |y - F(x')| for each x,y (point in dataset)'''
return abs(y - model(rv))
if debug:
print("rv: %s" % str(x))
print("cost: %s" % cost(x))
# if xtol=0, radius is difference in x,y and x,F(x); skip the optimization
try:
if not imax or not max(xtol): #iterables
return cost(x)
except TypeError:
if not xtol: #non-iterables
return cost(x)
# set the range constraints
xtol = asarray(xtol)
bounds = list(zip( x - xtol, x + xtol ))
if debug:
print("lower: %s" % str(zip(*bounds)[0]))
print("upper: %s" % str(zip(*bounds)[1]))
# optimize where initially x' = x
stepmon = Monitor()
if debug: stepmon = VerboseMonitor(1)
#XXX: edit settings?
MINMAX = 1 #XXX: confirm MINMAX=1 is minimization
ftol = ytol
gtol = None # use VTRCOG
if ipop:
results = diffev2(cost, bounds, ipop, ftol=ftol, gtol=gtol, \
itermon = stepmon, maxiter=imax, bounds=bounds, \
full_output=1, disp=0, handler=False)
else:
results = fmin_powell(cost, x, ftol=ftol, gtol=gtol, \
itermon = stepmon, maxiter=imax, bounds=bounds, \
full_output=1, disp=0, handler=False)
#solved = results[0] # x'
func_opt = MINMAX * results[1] # cost(x')
if debug:
print("solved: %s" % results[0])
print("cost: %s" % func_opt)
# get the minimum distance |y - F(x')|
return func_opt
#return results[0], func_opt
#########################################################################
#XXX: better to do a single optimization rather than for each point ???
d = [radius(model, point, ytol, xtol, ipop, imax) for point in target]
return infeasibility(d, cutoff)
