Re: Dvorak (& Lojban)

["Lee Sau Dan ~{@nJX6X~}" <sdlee@CS.HKU.HK>]

>>>>> "HACKER" == HACKER G N <c9709244@ALINGA.NEWCASTLE.EDU.AU> writes:


    HACKER> Does this mean that there are only as many keys on a
    HACKER> Chanjie keyboard as there are on a QWERTY keyboard?

Yes.  Indeed, it uses only 25 keys (excluding the space bar).

To input Chinese  into  the computer, the  typical device  is a normal
(e.g.  US 101-key) keyboard.  Nowadays, there  are other devices, such
as pen input  tablet (a digitizer,   used usually by  serious users of
CAD)  and   voice   input (employing   voice  recognition  techology).
Although these latter devices are more intuitive to use, the inputting
speeds are far below that of using a keyboard.

Many  "methods"  have been invented  for   inputting Chinese  into the
computer using  the standard keyboard.  Some  of them require the user
to type in a phonetic transcription  (e.g.  Pinyin) of a character and
then lists all  characters with  that pronunciation  for the user   to
select from.  These methods  are generally slow, because the selection
lists are long and the  user has  to  be distracted by the  selection.
Blind-folded typing is  not   possible.  Changjie, however, bases   on
character shape (as mentioned before).   There are around 100 Changjie
radicals, classified into _24_ groups, with  each group mapping to ONE
of the 26  letter  keys of  a US  keyboard,  ignoring the  distinction
between upper/lower cases.   One more  key  is used for special  cases
(those character that cannot be easily  broken up into radicals).  So,
only 25 keys are needed.

In  Changjie, the  average number of  keystrokes  (excluding the space
bar, which has to  be depressed after  keying in the radicals of  each
character)  per character is   3.5.  Touch-typing is possible, because
the Changjie codes of characters seldom have collisions.  So, the user
seldom has to  select from  candidate lists  as in the  phonetic-based
methods.  The typing  speed can  be  up  to  60 char/min for   trained
typists, and up to 200 char/min for wizards.



    HACKER> Because if so, that's pretty impressive, considering how
    HACKER> many characters there are in Chinese.

There  aren't many Chinese   characters  in  common use.  There    are
altogether tens of thousands of them, if we count  all those that have
appeared in these 3000 years, and count variants of the same character
as different characters.

However,  the number  of  characters frequently  used by newspapers is
around 6000 -- the number of characters that a ordinary student should
have learnt  in primary  school.   For casual writings (e.g.  personal
letters, diaries, etc.) this count would drop to 3000, or even less.


On  the computer, around 20000  Chinese characters are available.  So,
theoretically, if we  use only those   26 Latin letters to  encode the
characters, we can at best achieve a code length of

        log_{26} (20000) = 3.04

for each character.  Some people design inputting methods with as much
as 40 base letters (mapped to those 40 keys on and  below the row of 1
-- 0) and for such methods, the minimum code length is about:

        log_{40} (20000) = 2.68

Since it is possible  to assign shorter codes  to more frequently used
characters, the *weighted* average code  length can approach _2_, i.e.
an average  of 2 keystrokes (excluding  the space bar which terminates
the input of a character)  per character is possible.  Such  inputting
methods exist,  but are not as  common as Changjie, which is available
on almost all system supporting BIG5 encoding.




--
Lee Sau Dan                     'u&u40(Big5)                    ~{@nJX6X~}(HZ)
.----------------------------------------------------------------------------.
| http://www.cs.hku.hk/~sdlee                        e-mail: sdlee@cs.hku.hk |
`----------------------------------------------------------------------------'