def obj_to_str(obj):
    """ get class string from object 
    
    Examples
    --------
    
    >>> print(obj_to_str([1,2,3]).split('.')[-1])
    list
    
    >>> import numpy as np
    >>> print(obj_to_str(np.array([1,2,3])))
    numpy.ndarray
       
    """
    mod_str = obj.__class__.__module__
    name_str = obj.__class__.__name__
    if mod_str == '__main__':
        return name_str
    else:
        return '.'.join([mod_str, name_str])
