mapping None values to ''

[micklee74@hotmail.com]

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

[Tim Chase]

Re: mapping None values to ''

> i wish to map None or "None" values to "".[color=blue]
> 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[/color]

I'd consider this a VeryBadIdea(tm) . However, given Python's
introspective superpowers, it *can* be done (even if it most
likely *shouldn't* be done). That caveat out of the way, here goes:
[color=blue][color=green][color=darkred]
>>> for scope in [locals, globals]:[/color][/color][/color]
.... s = scope()
.... for vbl, value in s.items():
.... if value == None or (type(value) == type("") and
value == 'None'):
.... s[vbl] = ''


seems to do the trick. You may, likely, just want to operate on
locals, not every last global variable in your project, in which
case you can just use

s = locals()
for vbl, value in s.items():
...

There may be some better way to determing whether an item is a
string than my off-the-cufff

type(value) == type("")

but it worked to prevent trying to compare non-strings to the
string 'None' later in the sub-clause of the if statement.

Note that if you wrap this in a function, you'll may have to pass
in locals() as a parameter because otherwise, inside your
function, you'll have a different set of available locals that
you did when you called the function. :)

Beware your foot when shooting this gun...it likes to aim at feet.

-tkc

[imho]

Re: mapping None values to ''

micklee74@hotma il.com ha scritto:[color=blue]
> 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
>[/color]

You already filtered [a,b,c] in the comprehension list, so you just have
to map all its values to "":

map(lambda x:"" , [i for i in [a,b,c] if i in ("None",None ) ])

[Gerard Flanagan]

Re: mapping None values to ''


micklee74@hotma il.com wrote:[color=blue]
> 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[/color]

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]

[Roberto Bonvallet]

Re: mapping None values to ''

imho <certo@comeno.i t>:[color=blue]
> map(lambda x:"" , [i for i in [a,b,c] if i in ("None",None ) ])[/color]

You don't need map when using list comprehensions:

["" for i in [a, b, c] if i in ("None", None)]

--
Roberto Bonvallet

[Scott David Daniels]

Re: mapping None values to ''

Roberto Bonvallet wrote:[color=blue]
> imho <certo@comeno.i t>:[color=green]
>> map(lambda x:"" , [i for i in [a,b,c] if i in ("None",None ) ])[/color]
> You don't need map when using list comprehensions:
> ["" for i in [a, b, c] if i in ("None", None)]
>[/color]
More like:

[(i, "")[i in ("None", None)] for i in [a,b,c]]

--
--Scott David Daniels
scott.daniels@a cm.org

[Max Erickson]

Re: mapping None values to ''

"Roberto Bonvallet" <rbonvall@gmail .com> wrote:[color=blue]
> You don't need map when using list comprehensions:
>
> ["" for i in [a, b, c] if i in ("None", None)]
>[/color]

That loses list elements that aren't in the tests:
[color=blue][color=green][color=darkred]
>>> a=7
>>> b="None"
>>> c=None
>>> ["" for i in [a,b,c] if i in ("None",None )][/color][/color][/color]
['', ''][color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

max

[Steven Bethard]

Re: mapping None values to ''

Scott David Daniels wrote:[color=blue]
> Roberto Bonvallet wrote:[color=green]
>> imho <certo@comeno.i t>:[color=darkred]
>>> map(lambda x:"" , [i for i in [a,b,c] if i in ("None",None ) ])[/color]
>> You don't need map when using list comprehensions:
>> ["" for i in [a, b, c] if i in ("None", None)]
>>[/color]
> More like:
>
> [(i, "")[i in ("None", None)] for i in [a,b,c]][/color]

Or in Python 2.5:

Python 2.5a2 (trunk:46491M, May 27 2006, 14:43:55) [MSC v.1310 32 bit
(Intel)] on win32
Type "help", "copyright" , "credits" or "license" for more information.[color=blue][color=green][color=darkred]
>>> a = 0
>>> b = None
>>> c = None
>>> a, b, c = ('' if x in (None, 'None') else x for x in (a, b, c))
>>> a, b, c[/color][/color][/color]
(0, '', '')

But someone please shoot me if I ever use something like that in
production code. ;)

STeVe

[imho]

Re: mapping None values to ''

Roberto Bonvallet ha scritto:[color=blue]
> imho <certo@comeno.i t>:[color=green]
>> map(lambda x:"" , [i for i in [a,b,c] if i in ("None",None ) ])[/color]
>
> You don't need map when using list comprehensions:
>
> ["" for i in [a, b, c] if i in ("None", None)]
>[/color]

I know that... I tried to match the idiom used by the o.p. :-)