import re


def rmspecialchars(value):
    """   
    Remove any special characters except period (.) and negative (-) from numeric values
    
    Parameters
    ----------
    value : string
        String value to remove any existing characters from
        
    Returns
    -------
    value : string
        String value to without any special characters
        
    Examples
    --------
    >>> import helpers
    >>> helpers.rmspecialchars(value = "*6.5_")
    6.5
    >>> helpers.rmspecialchars(value = "ICE")
    ICE
    >>> helpers.rmspecialchars(value = "-4.2")
    -4.2
    >>> helpers.rmspecialchars(value = "")
    
    >>> helpers.rmspecialchars(value = "%&!@#8.32&#*;")
    8.32
    """
    value = re.sub("[^A-Za-z0-9.-]+", "", value)
    
    return value