以下代码可以从先前的
x
保存并重新启动,但我猜你想要保存和重新启动更多状态,比如渐变;你能澄清一下吗?
另外参见
basinhopping,该程序具有漂亮的图形用户界面,
pele-python。
""" Funcgradmn: wrap f() and grad(), save all x[] f[] grad[] to plot or restart """
from __future__ import division
import numpy as np
__version__ = "2016-10-18 oct denis"
class Funcgradmon(object):
""" Funcgradmn: wrap f() and grad(), save all x[] f[] grad[] to plot or restart
Example: minimize, save, restart --
fg = Funcgradmon( func, gradfunc, verbose=1 )
# fg(x): f(x), g(x) for minimize( jac=True )
# run 100 iter (if linesearch, 200-300 calls of fg()) --
options = dict( maxiter=100 ) # ...
min0 = minimize( fg, x0, jac=True, options=options )
fg.savez( "0.npz", paramstr="..." ) # to plot or restart
# restart from x[50] --
# (won't repeat the previous path from 50
# unless you save and restore the whole state of the optimizer)
x0 = fg.restart( 50 )
# change params ...
min50 = minimize( fg, x0, jac=True, options=options )
"""
def __init__( self, func, gradfunc, verbose=1 ):
self.func = func
self.gradfunc = gradfunc
self.verbose = verbose
self.x, self.f, self.g = [], [], []
self.t = 0
def __call__( self, x ):
""" f, g = func(x), gradfunc(x); save them; return f, g """
x = np.asarray_chkfinite( x )
f = self.func(x)
g = self.gradfunc(x)
g = np.asarray_chkfinite( g )
self.x.append( np.copy(x) )
self.f.append( _copy( f ))
self.g.append( np.copy(g) )
if self.verbose:
print "%3d:" % self.t ,
fmt = "%-12g" if np.isscalar(f) else "%s\t"
print fmt % f ,
print "x: %s" % x ,
print "\tgrad: %s" % g
self.t += 1
return f, g
def restart( self, n ):
""" x0 = fg.restart( n ) returns x[n] to minimize( fg, x0 )
"""
x0 = self.x[n]
del self.x[:n]
del self.f[:n]
del self.g[:n]
self.t = n
if self.verbose:
print "Funcgradmon: restart from x[%d] %s" % (n, x0)
return x0
def savez( self, npzfile, **kw ):
""" np.savez( npzfile, x= f= g= ) """
x, f, g = map( np.array, [self.x, self.f, self.g] )
if self.verbose:
asum = "f: %s \nx: %s \ng: %s" % (
_asum(f), _asum(x), _asum(g) )
print "Funcgradmon: saving to %s: \n%s \n" % (npzfile, asum)
np.savez( npzfile, x=x, f=f, g=g, **kw )
def load( self, npzfile ):
load = np.load( npzfile )
x, f, g = load["x"], load["f"], load["g"]
if self.verbose:
asum = "f: %s \nx: %s \ng: %s" % (
_asum(f), _asum(x), _asum(g) )
print "Funcgradmon: load %s: \n%s \n" % (npzfile, asum)
self.x = list( x )
self.f = list( f )
self.g = list( g )
self.loaddict = load
return self.restart( len(x) - 1 )
def _asum( X ):
""" one-line array summary: "shape type min av max" """
if not hasattr( X, "dtype" ):
return str(X)
return "%s %s min av max %.3g %.3g %.3g" % (
X.shape, X.dtype, X.min(), X.mean(), X.max() )
def _copy( x ):
return x if x is None or np.isscalar(x) \
else np.copy( x )
if __name__ == "__main__":
import sys
from scipy.optimize import minimize, rosen, rosen_der
np.set_printoptions( threshold=20, edgeitems=10, linewidth=140,
formatter = dict( float = lambda x: "%.3g" % x ))
dim = 3
method = "cg"
maxiter = 10
for arg in sys.argv[1:]:
exec( arg )
print "\n", 80 * "-"
print "Funcgradmon: dim %d method %s maxiter %d \n" % (
dim, method, maxiter )
x0 = np.zeros( dim )
fg = Funcgradmon( rosen, rosen_der, verbose=1 )
options = dict( maxiter=maxiter )
min0 = minimize( fg, x0, jac=True, method=method, options=options )
fg.savez( "0.npz", paramstr="..." )
x0 = fg.restart( 5 )
min5 = minimize( fg, x0, jac=True, method=method, options=options )
fg.savez( "5.npz", paramstr="..." )
jac
是你的函数,你可以轻松地使用 *kwarg 在第一次调用时加载并返回xx.jac
。