mapping None values to ''

[Gerard Flanagan]

micklee74 at hotmail.com wrote:
> hi
> i wish to map None or "None" values to "".
> eg
> a = None
> b = None
> c = "None"
>
> map( <something>  ,  [i for i in [a,b,c] if i in ("None",None) ])
>
> I can't seem to find a way to put all values to "". Can anyone help?
> thanks

a = [None, 'None', None]

def filtre(x):
    if x is None or x == 'None':
        return ''
    else:
        return x

assert map(filtre, a) == ['', '', '']

a = [1, 2, None, 'None', 3, 4]

assert map(filtre, a) == [1, 2, '', '', 3, 4]