manipulation.py 文件源码

def as_symbol(expr):
    """
    Extract the "main" symbol from a SymPy object.
    """
    try:
        return Number(expr)
    except (TypeError, ValueError):
        pass
    if isinstance(expr, str):
        return Symbol(expr)
    elif isinstance(expr, Dimension):
        return Symbol(expr.name)
    elif expr.is_Symbol:
        return expr
    elif isinstance(expr, Indexed):
        return expr.base.label
    elif isinstance(expr, Function):
        return Symbol(expr.__class__.__name__)
    else:
        raise TypeError("Cannot extract symbol from type %s" % type(expr))