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