Dictionary vs if-elif?

[Wolfgang Grafen]

William Dandreta wrote:

> Here is a code snippet
> -------------------------------------------------------------------------
> bogusCodes = { '1.':'', '31':'', '90':'', 'AZ':'', 'BH':'', 'C1':'',
>                'CB':'', 'FR':'', 'HD':'', 'JF':'', 'KL':'', 'KU':'',
>                'LU':'', 'ON':'', 'PF':'', 'Q3':'', 'UP':'', 'W4':'',
>                'WO':''}
>
> item  = data.readline()
> while item:
>   if (item[1:2] in digits) and (item[0:1] == 'D'):
>     goodVend.write(item)
>   elif vendors.has_key(item[0:2]):
>     goodVend.write(item)
>   elif bogusCodes.has_key(item[0:2]):
>     pass
>   else:
>     missingVend.write('Vendor code %s is missing from file VendCode.txt\n' %
> item[0:2])
>   item  = data.readline()
> ---------------------------------------------------------------
> originally I had it written like so:
>
> if ...:
>   pass
> elif...:
>   pass
> etc.
> -------------------------
> another possibility is and if statement with a very complex condition:
> if a or b or c ...:
>   pass
> else :
> etc
> ---------------------
> Is there a better way to do it?
> Which of these three would be the preferred method?
>
> Bill

Hi Bill,

try a very fast version:

bogusCodes = ['1.', '31', '90', 'AZ', 'BH', 'C1',
              'CB', 'FR', 'HD', 'JF', 'KL', 'KU',
              'LU', 'ON', 'PF', 'Q3', 'UP', 'W4',
              'WO']

DDIGITS    = map(lambda x:'D%s'%x,range(10)

vendorCodes = ['2.','41']  # as an example

def PASS(key):
    pass

dict = {}

for key in bogusCodes:
    dict[key] = PASS

for key in vendorCodes + DDIGITS:
    dict[key] = goodVend.write

while 1:
    item = data.readline()
    try:
        key = item[:2]
        dict[key](item)
    except KeyError:
        missingVend.write(
          'Vendor code %s is missing from file VendCode.txt\n'%item[0:2])

Wolfgang