forked from sympy/sympy
/
lambdarepr.py
66 lines (58 loc) · 1.9 KB
/
lambdarepr.py
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from str import StrPrinter
def _find_first_symbol(expr):
for atom in expr.atoms():
if atom.is_Symbol:
return atom
raise ValueError('expression must contain a Symbol: %r' % expr)
class LambdaPrinter(StrPrinter):
"""
This printer converts expressions into strings that can be used by
lambdify.
"""
def _print_Matrix(self, expr):
return "Matrix([%s])"%expr._format_str(self._print, ",")
def _print_Piecewise(self, expr):
from sympy.core.sets import Interval
args = expr.args
result = []
i = 0
for arg in expr.args:
e = arg.expr
c = arg.cond
result.append('((')
result.append(self._print(e))
result.append(') if (')
if isinstance(c, Interval):
result.append(self._print(c.contains(_find_first_symbol(e))))
else:
result.append(self._print(c))
result.append(') else (')
i += 1
result = result[:-1]
result.append(') else None)')
result.append(')'*(2*i - 2))
return ''.join(result)
def _print_And(self, expr):
result = ['(']
for arg in expr.args:
result.extend(['(', self._print(arg), ')'])
result.append(' and ')
result = result[:-1]
result.append(')')
return ''.join(result)
def _print_Or(self, expr):
result = ['(']
for arg in expr.args:
result.extend(['(', self._print(arg), ')'])
result.append(' or ')
result = result[:-1]
result.append(')')
return ''.join(result)
def _print_Not(self, expr):
result = ['(', 'not (', self._print(expr.args[0]), '))']
return ''.join(result)
def lambdarepr(expr, **settings):
"""
Returns a string usable for lambdifying.
"""
return LambdaPrinter(settings).doprint(expr)