def lambdastr(args, expr, printer=None, dummify=False): """ Returns a string that can be evaluated to a lambda function. Examples ======== >>> from sympy.abc import x, y, z >>> from sympy.utilities.lambdify import lambdastr >>> lambdastr(x, x**2) 'lambda x: (x**2)' >>> lambdastr((x,y,z), [z,y,x]) 'lambda x,y,z: ([z, y, x])' Although tuples may not appear as arguments to lambda in Python 3, lambdastr will create a lambda function that will unpack the original arguments so that nested arguments can be handled: >>> lambdastr((x, (y, z)), x + y) 'lambda _0,_1: (lambda x,y,z: (x + y))(*list(__flatten_args__([_0,_1])))' """ # Transforming everything to strings. from sympy.matrices import DeferredVector from sympy import Dummy, sympify, Symbol, Function, flatten if printer is not None: if inspect.isfunction(printer): lambdarepr = printer else: if inspect.isclass(printer): lambdarepr = lambda expr: printer().doprint(expr) else: lambdarepr = lambda expr: printer.doprint(expr) else: #XXX: This has to be done here because of circular imports from sympy.printing.lambdarepr import lambdarepr def sub_args(args, dummies_dict): if isinstance(args, str): return args elif isinstance(args, DeferredVector): return str(args) elif iterable(args): dummies = flatten([sub_args(a, dummies_dict) for a in args]) return ",".join(str(a) for a in dummies) else: #Sub in dummy variables for functions or symbols if isinstance(args, (Function, Symbol)): dummies = Dummy() dummies_dict.update({args: dummies}) return str(dummies) else: return str(args) def sub_expr(expr, dummies_dict): try: expr = sympify(expr).xreplace(dummies_dict) except Exception: if isinstance(expr, DeferredVector): pass elif isinstance(expr, dict): k = [sub_expr(sympify(a), dummies_dict) for a in expr.keys()] v = [sub_expr(sympify(a), dummies_dict) for a in expr.values()] expr = dict(zip(k, v)) elif isinstance(expr, tuple): expr = tuple(sub_expr(sympify(a), dummies_dict) for a in expr) elif isinstance(expr, list): expr = [sub_expr(sympify(a), dummies_dict) for a in expr] return expr # Transform args def isiter(l): return iterable(l, exclude=(str, DeferredVector, NotIterable)) if isiter(args) and any(isiter(i) for i in args): from sympy.utilities.iterables import flatten import re dum_args = [str(Dummy(str(i))) for i in range(len(args))] iter_args = ','.join( [i if isiter(a) else i for i, a in zip(dum_args, args)]) lstr = lambdastr(flatten(args), expr, printer=printer, dummify=dummify) flat = '__flatten_args__' rv = 'lambda %s: (%s)(*list(%s([%s])))' % (','.join(dum_args), lstr, flat, iter_args) if len(re.findall(r'\b%s\b' % flat, rv)) > 1: raise ValueError('the name %s is reserved by lambdastr' % flat) return rv dummies_dict = {} if dummify: args = sub_args(args, dummies_dict) else: if isinstance(args, str): pass elif iterable(args, exclude=DeferredVector): args = ",".join(str(a) for a in args) # Transform expr if dummify: if isinstance(expr, str): pass else: expr = sub_expr(expr, dummies_dict) expr = lambdarepr(expr) return "lambda %s: (%s)" % (args, expr)
def lambdastr(args, expr, printer=None, dummify=False): """ Returns a string that can be evaluated to a lambda function. Examples ======== >>> from sympy.abc import x, y, z >>> from sympy.utilities.lambdify import lambdastr >>> lambdastr(x, x**2) 'lambda x: (x**2)' >>> lambdastr((x,y,z), [z,y,x]) 'lambda x,y,z: ([z, y, x])' Although tuples may not appear as arguments to lambda in Python 3, lambdastr will create a lambda function that will unpack the original arguments so that nested arguments can be handled: >>> lambdastr((x, (y, z)), x + y) 'lambda _0,_1: (lambda x,y,z: (x + y))(*list(__flatten_args__([_0,_1])))' """ # Transforming everything to strings. from sympy.matrices import DeferredVector from sympy import Dummy, sympify, Symbol, Function, flatten if printer is not None: if inspect.isfunction(printer): lambdarepr = printer else: if inspect.isclass(printer): lambdarepr = lambda expr: printer().doprint(expr) else: lambdarepr = lambda expr: printer.doprint(expr) else: #XXX: This has to be done here because of circular imports from sympy.printing.lambdarepr import lambdarepr def sub_args(args, dummies_dict): if isinstance(args, str): return args elif isinstance(args, DeferredVector): return str(args) elif iterable(args): dummies = flatten([sub_args(a, dummies_dict) for a in args]) return ",".join(str(a) for a in dummies) else: #Sub in dummy variables for functions or symbols if isinstance(args, (Function, Symbol)): dummies = Dummy() dummies_dict.update({args : dummies}) return str(dummies) else: return str(args) def sub_expr(expr, dummies_dict): try: expr = sympify(expr).xreplace(dummies_dict) except Exception: if isinstance(expr, DeferredVector): pass elif isinstance(expr, dict): k = [sub_expr(sympify(a), dummies_dict) for a in expr.keys()] v = [sub_expr(sympify(a), dummies_dict) for a in expr.values()] expr = dict(zip(k, v)) elif isinstance(expr, tuple): expr = tuple(sub_expr(sympify(a), dummies_dict) for a in expr) elif isinstance(expr, list): expr = [sub_expr(sympify(a), dummies_dict) for a in expr] return expr # Transform args def isiter(l): return iterable(l, exclude=(str, DeferredVector, NotIterable)) if isiter(args) and any(isiter(i) for i in args): from sympy.utilities.iterables import flatten import re dum_args = [str(Dummy(str(i))) for i in range(len(args))] iter_args = ','.join([i if isiter(a) else i for i, a in zip(dum_args, args)]) lstr = lambdastr(flatten(args), expr, printer=printer, dummify=dummify) flat = '__flatten_args__' rv = 'lambda %s: (%s)(*list(%s([%s])))' % ( ','.join(dum_args), lstr, flat, iter_args) if len(re.findall(r'\b%s\b' % flat, rv)) > 1: raise ValueError('the name %s is reserved by lambdastr' % flat) return rv dummies_dict = {} if dummify: args = sub_args(args, dummies_dict) else: if isinstance(args, str): pass elif iterable(args, exclude=DeferredVector): args = ",".join(str(a) for a in args) # Transform expr if dummify: if isinstance(expr, str): pass else: expr = sub_expr(expr, dummies_dict) expr = lambdarepr(expr) return "lambda %s: (%s)" % (args, expr)