I forgot to handle upper case. Note that the following is (~5%)
faster than calling .upper() on the input::
_phone_chars = {
'a': '2',
'b': '2',
'c': '2',
'd': '3',
'e': '3',
'f': '3',
'g': '4',
'h': '4',
'i': '4',
'j': '5',
'k': '5',
'l': '5',
'm': '6',
'n': '6',
'o': '6',
'p': '7',
'q': '7',
'r': '7',
's': '7',
't': '8',
'u': '8',
'v': '8',
'w': '9',
'x': '9',
'y': '9',
'z': '9',
}
_phone_chars_compiled = None
def phone2numeric(value):
global _phone_chars_compiled
if _phone_chars_compiled is None:
_phone_chars_compiled = {}
for i in range(256):
a = chr(i)
b = a.upper()
_phone_chars_compiled[a] = _phone_chars.get(a, a)
_phone_chars_compiled[b] = _phone_chars.get(b, b)
return ''.join(map(_phone_chars_compiled.__getitem__, value))
Of course, premature optimization is the root of all evil. There is
certainly a lot more code here, and I'm not sure phone2numeric is that
often called in applications. (As opposed to database/template
operations.) I'll leave you with a great comment on python
optimization [1].
Cheers,
Mike
1: http://www.codeirony.com/?p=9
On Fri, Jan 15, 2010 at 9:15 AM, Mike Axiak <m...@axiak.net> wrote:
> If you really want to be fast, you can do the following, a la urllib.quote::
>
> _phone_chars = {'a': '2', 'b': '2', 'c': '2', 'd': '3', 'e': '3',
> 'f': '3', 'g': '4', 'h': '4', 'i': '4', 'j': '5', 'k':
> '5', 'l': '5',
> 'm': '6', 'n': '6', 'o': '6', 'p': '7', 'q': '7', 'r':
> '7', 's': '7',
> 't': '8', 'u': '8', 'v': '8', 'w': '9', 'x': '9', 'y':
> '9', 'z': '9',
> }
> _phone_chars_compiled = None
>
> def phone2number(szinput):
> global _phone_chars_compiled
> if _phone_chars_compiled is None:
> _phone_chars_compiled = {}
> for i in range(256):
> a = chr(i)
> _phone_chars_compiled[a] = _phone_chars.get(a, a)
>
> return ''.join(map(_phone_chars_compiled.__getitem__, szinput))
>
> It yields a 4x speedup over your code (which constructs the map on
> every iteration?). Of course we're talking about microseconds, but I
> guess every bit counts...
>
> Cheers,
> Mike
>
> On Fri, Jan 15, 2010 at 6:41 AM, Andrew Gwozdziewycz <apg...@gmail.com> wrote:
>> Why use regular expressions at all for this? A timeit benchmark shows
>> a greater than 4x speedup with a rangetest in a loop over the string:
>>
>> def phone2number(str):
>> chars = {'a': '2', 'b': '2', 'c': '2', 'd': '3', 'e': '3',
>> 'f': '3', 'g': '4', 'h': '4', 'i': '4', 'j': '5', 'k': '5', 'l': '5',
>> 'm': '6', 'n': '6', 'o': '6', 'p': '7', 'q': '7', 'r': '7', 's': '7',
>> 't': '8', 'u': '8', 'v': '8', 'w': '9', 'x': '9', 'y': '9', 'z': '9',
>> }
>>
>> out = ''
>> for n in phone:
>> x = n.lower()
>> o = ord(x)
>> if o > 96 and o < 123:
>> out += chars[x.lower()]
>> else:
>> out += x
>> return out
>>
>> I know your patch was just adding back Q and Z, but there's no need
>> for a regular expression here.
>>
>> On Thu, Jan 14, 2010 at 5:33 PM, Gabriel Hurley <gab...@gmail.com> wrote:
>>> I've opened a ticket and submitted a patch that fixes this strange
>>> oversight: http://code.djangoproject.com/ticket/12613
>>>
>>> Thanks!
>>> - Gabriel
>>>
>>> On Jan 14, 5:05 am, Harro <hvdkl...@gmail.com> wrote:
>>>> hmm that's indeed weird. The regex excludes those as well
>>>> specifically.
>>>> The Q and Z should be added or a comment should be added to the code
>>>> explaining the reason for leaving them out.
>>>>
>>>> On Jan 14, 11:23 am, Gabriel Hurley <gab...@gmail.com> wrote:
>>>>
>>>>
>>>>
>>>> > 1. Is there a reason Django's phone2numeric method doesn't work for
>>>> > the letters Q or Z? I realize that those two letters are the ones that
>>>> > share four letters to a number instead of the standard three, but
>>>> > that's no reason to leave them out. Most modern phones include the
>>>> > full alphabet on their keys and it's silly not to let people convert
>>>> > those two letters.
>>>>
>>>> > If there's no reason, I'd be happy to submit a patch since it's such
>>>> > an easy fix.
>>>>
>>>> > 2. I was also wondering if there's a reason that the dictionary of
>>>> > numbers/letters used in that function is in such a seemingly random
>>>> > order... is there some brilliant logic behind it?
>>>>
>>>> > The source for the function I'm referring to is here:
>>>>
>>>> >http://code.djangoproject.com/browser/django/trunk/django/utils/text....
>>>>
>>>> > Thanks!
>>>>
>>>> > - Gabriel
>>>
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>>
>>
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