54 lines
1.3 KiB
Python
54 lines
1.3 KiB
Python
from . import rl
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from .core import do_one, exhaust, switch
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from .traverse import top_down
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def subs(d, **kwargs):
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""" Full simultaneous exact substitution.
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Examples
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========
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>>> from sympy.strategies.tools import subs
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>>> from sympy import Basic, S
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>>> mapping = {S(1): S(4), S(4): S(1), Basic(S(5)): Basic(S(6), S(7))}
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>>> expr = Basic(S(1), Basic(S(2), S(3)), Basic(S(4), Basic(S(5))))
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>>> subs(mapping)(expr)
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Basic(4, Basic(2, 3), Basic(1, Basic(6, 7)))
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"""
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if d:
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return top_down(do_one(*map(rl.subs, *zip(*d.items()))), **kwargs)
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else:
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return lambda x: x
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def canon(*rules, **kwargs):
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""" Strategy for canonicalization.
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Explanation
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===========
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Apply each rule in a bottom_up fashion through the tree.
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Do each one in turn.
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Keep doing this until there is no change.
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"""
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return exhaust(top_down(exhaust(do_one(*rules)), **kwargs))
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def typed(ruletypes):
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""" Apply rules based on the expression type
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inputs:
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ruletypes -- a dict mapping {Type: rule}
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Examples
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========
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>>> from sympy.strategies import rm_id, typed
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>>> from sympy import Add, Mul
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>>> rm_zeros = rm_id(lambda x: x==0)
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>>> rm_ones = rm_id(lambda x: x==1)
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>>> remove_idents = typed({Add: rm_zeros, Mul: rm_ones})
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"""
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return switch(type, ruletypes)
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