DZone Snippets: default code

Windows XP System Variables

dubby (Dave) — Fri, 07 Sep 2007 09:09:44 GMT

// Windows XP Default System Variables



%SystemDrive%  		C:



%SystemRoot% 		C:\WINNT, C:\WINDOWS



%SystemDirectory% 	C:\WINNT\System32, C:\WINDOWS\System32



%WinDir% 		C:\WINNT, C:\WINDOWS, C:\WINNT\Program Files



%ComSpec% 		C:\WINNT\system32\cmd.exe



%Temp% 			C:\DOCUME~1\Usr\LOCALS~1\Temp from C:\Documents and Settings\Usr\Local Settings\Temp



%HOMEDRIVE% 		C: The drive letter associated with the user's home directory



%HOMEPATH% 		The path to the user's home directory (excluding drive): \Documents and Settings\Guest



%OS% 			Windows_NT -> The operating system the user is running



%USERDOMAIN% 		The name of the domain that contains the user's account



%USERNAME% 		The user's name

Default Sort Order For Rails models

mcmoyer () — Fri, 03 Aug 2007 20:02:50 GMT

// provide a default sort order in case an order by clause isn't defined in the find clause
// Place this code somewhere in your model's class file.



        def self.find(*args)

          order_arg = args.collect do |arg|

            if arg.kind_of? Hash 

              if arg.keys[0] == :order

                arg

              end

            end

          end



          if order_arg.compact.empty?

            args << {:order=>"place order by clause here e.g. 'name asc'"}

          end

          

          super

        end

Default dictionary

korakot (Korakot Chaovavanich) — Thu, 15 Sep 2005 01:11:37 GMT

I always want to do this, like I did in Perl.



>> d = DefaultDict(0)

>> d[key] += 1     # no need to use d.get or d.setdefault



>> d = DefaultDict([])  # similarly with list value

>> d[key].append(item)

See the implementation by Peter Norvig (of AI & Google fame)
here

Counting characters in string

korakot (Korakot Chaovavanich) — Tue, 26 Jul 2005 18:39:46 GMT



>>> s = 'a;jfkd;aflhakfhaskfjalghlakfhfnkjafyksd'

>>> cnt = {}

>>> for c in s:

	cnt[c] = cnt.get(c,0) + 1



>>> print cnt

{'a': 7, 'd': 2, 'g': 1, 'f': 7, 'h': 4, 'k': 6, 'j': 3, 'l': 3, 'n': 1, 's': 2, 'y': 1, ';': 2}

This can be used to count any distribution.
Note the use of dict.get(key,default) to set to 0
if the key is not avaiable.
If this were perl, I would just do a
cnt[c] += 1
But python will give an error instead of returning 0.
It's not too bad, though.