Well,
Just to make a global figure, ICU collation is to binary collation what
CouchDB is to RDBMS.
If you look at the link you gave for algorithm reference, you have :
On 1.1 multi level comparison, you have in the table this example :
L2 Accents role < r*ô*le < roles
To be complete you should also show :
L2 Accents role < r*ô*le < roles < r*ô*les
Seems stupid but it's not as it's a language, and o or ô are same letter, as
they explain under :
"For example, the L2 example shows that difference between an *o* and an
accented * ô* is swamped by an L1 difference (the presence or absence of an
*s*)"
If you even go to 1.3, you have in the french ordering :
Normal Accent Ordering cote < cot*é* < c*ô*te < côté French Accent
Ordering cote
< c*ô*te < cot*é* < côté
To be fair i'm French, so may be that's the reason it not seems odd to me.
Now if we follow the main algorithm in 4. :
we have with your three "words" : a A aa, i even add AA
Step 1 : Normalize (easy no special character from your example)
a -> a as LATIN SMALL LETTER A (see
http://www.unicode.org/Public/UCA/latest/allkeys.txt)
A -> A as LATIN CAPITAL LETTER A
aa -> aa as LATIN SMALL LETTER A , LATIN SMALL LETTER A
Step 2 : Produce Array :
a -> [.1141.0020.0002.0061]
A ->[.1141.0020.0008.0041]
aa -> [.1141.0020.0002.0061], [.1141.0020.0002.0061]
AA ->[.1141.0020.0008.0041], [.1141.0020.0008.0041]
Step 3 : Form Sort Key
the algo is something like :
s = string to sort
sArray = String to sort produce as array
So :
s="a"=["a"]
sArray=[[1141,0020,002,0061]]
s="A"=["A"]
sArray=[[1141,0020,008,0041]]
s="aa"=["a","a"]
sArray=[[1141,0020,002,0061],[1141,0020,002,0061]]
s="A"=["A"]
sArray=[[1141,0020,008,0041],[1141,0020,008,0041]]
(let's say we use Level 3)
sortKey=[];
for (i=0; i<3; i++) {
for(j=0; j [1141,0020,002]
A -> [1141,0020,008]
aa-> [1141,1141,020,020,002,002]
AA ->[1141,1141,020,020,008,008]
Step 4 : Compare :
First element :
1141 ==1141==1141==1141
No order yet,
Second element :
0020==0020 < 1141==1141
So order up to now is a==A < aa==AA
Third element (only for a==A):
002<008
so a < A < aa==AA
Third element (only for aa=AA)
020==020
still aa=AA
Fourth element (only for aa==AA)
020==020
still aa=AA
Fifth element (only for aa==AA)
002==008
so aa < AA
Finally
a
> Perhaps I'm not explaining my expectation well enough.
>
> The way I read the algorithm, the basic idea is that you take the
> weights for each character and concatenate them. then you run throw
> these representations and do a basic element wise comparison.
>
> I know that a and A have the same primary and secondary weights. But
> they have different tertiary weights.
>
> Thus as I read the algorithm (most likely missing the important clause
> affecting this) then when I compare a and A, A > a. I don't see why
> any other character is considered. A is fucking bigger than a. If
> there is a section that says, "Oh, btw, if one string is an exact
> prefix of the other as defined solely by primary weights, then the
> prefix sorts first" i would be happy as a pig in shit.
>
>
>
> On Thu, Apr 9, 2009 at 7:18 PM, Patrick Antivackis
> wrote:
> > Paul,
> >
> > 2009/4/10 Paul Davis
> >
> >> I've tried various combinations of UC_CASE_LEVEL, UC_CASE_FIRST, and
> >> UC_WEIGHT.
> >>
> >
> > This is really not enough. Doing this you only try to say to the
> collation
> > that a<< > but still it's an a upper, lower, witha tilde, with an accent or
> wathever.
> > All are just variation of A but still A.
> >
> > If you look at :
> > http://www.unicode.org/Public/UCA/latest/allkeys.txt
> >
> > and search for :
> >
> > 0061 ; [.1141.0020.0002.0061] # LATIN SMALL LETTER A
> >
> >
> > you will see a lot of A definition, but all have the same first element
> > :1141, they are all the same letter, other are just variation. So
> compared
> > to each of them they have an order but compared with an other letter they
> > all behave the same like an A
> >
> > So, now if you want to change order of primary element, you need to use
> > custom tailoring :
> > http://userguide.icu-project.org/collation/customization
> >
> > And you need to say thing like :
> > a < A (primary order)
> > So to simulate ASCII behaviour you should try something like : a < b < c
> > < ...... >
> > To be honest, i not tried, but that should work
> >
>
> Let me reiterate. I do *not* want A > b. I want A fucking greater than
> a. Or not greater. But this relation:
>
> a < A < aa
>
> to me means:
>
> a < A < a
>
> Am I the only one that finds that just a bit ridiculous?
>
> HTH,
> Paul Davis
>
> p.s. the cursing isn't directed at anyone here. I'm just fairly
> frustrated by that unicode algorithm.
>
> >
> >
> >
> >
> >
> >> Also, I still don't see anything in this damned collation algorithm
> >> that explains how A < aa. And this doesn't fall into the big/biggest
> >> comparison. The similar case would be Big < biggest. But I don't see
> >> anything in the damn collation algorithm document that talks about
> >> ignoring anything after primary weight in the case that one string is
> >> a prefix. In the various examples that I see I can't find anything
> >> that would contradict that expectation.
> >>
> >> Paul Davis
> >>
> >> For reference, the algorithm reference I'm using is this one:
> >> http://unicode.org/reports/tr10/
> >>
> >> I feel like printing the entire thing just so I can have a book burning.
> >>
> >> On Thu, Apr 9, 2009 at 6:39 PM, Patrick Antivackis
> >> wrote:
> >> > By the way, what customization did you try to send to ICU ?
> >> >
> >> > 2009/4/10 Paul Davis
> >> >
> >> >> Patrick,
> >> >>
> >> >> I'm not asking for this relationship:
> >> >>
> >> >> a < b < A < B
> >> >>
> >> >> Merely:
> >> >>
> >> >> a < aa < A
> >> >>
> >> >> The thing is that even when I try and specify explicitly that 'A;
> >> >> should come after 'a' I still can't get the expected "a < aa < A"
> >> >> behavior. In a nutshell, "Why the hell does the second 'a' alter the
> >> >> comparison?"
> >> >>
> >> >> HTH,
> >> >> Paul Davis
> >> >>
> >> >> On Thu, Apr 9, 2009 at 5:45 PM, Patrick Antivackis
> >> >> wrote:
> >> >> > It's quite normal as far as ICU is concerned.
> >> >> > ICU is about language not about ASCII code.
> >> >> > In ICU, case is the third element looked for comparison (same level
> >> than
> >> >> > circled letter in Nordic languages for example), so not very
> >> important.
> >> >> > So when you sort words together, a or A is still an a, so they are
> >> sorted
> >> >> > nearby. In ICU you can specify if you prefer a before A or A before
> a,
> >> >> but
> >> >> > not simply a before b before c.... before A before B before C.
> >> >> >
> >> >> > To have such behavior (like ASCII) you need to custom ICU in
> >> specifying
> >> >> the
> >> >> > collation you want almost letter by letter.
> >> >> > It is great for you, but what about Japanese users or Arabic users
> ??
> >> >> >
> >> >> > So this is definitely the right behaviour of ICU sorting
> (collation).
> >> >> >
> >> >> >
> >> >> > 2009/4/9 Brian Candler
> >> >> >
> >> >> >> > I've spent entirely too long on this now and I still can't for
> the
> >> >> >> > life of me figure out why A < aa.
> >> >> >>
> >> >> >> Time for an experimental, black-box approach:
> >> >> >>
> >> >> >> ----
> >> >> >> require 'rubygems'
> >> >> >> require 'restclient'
> >> >> >> require 'json'
> >> >> >>
> >> >> >> DB="http://127.0.0.1:5984/collator"
> >> >> >>
> >> >> >> RestClient.delete DB rescue nil
> >> >> >> RestClient.put "#{DB}",""
> >> >> >>
> >> >> >> (32..126).each do |c|
> >> >> >> RestClient.put "#{DB}/#{c.to_s(16)}", {"x"=>c.chr}.to_json
> >> >> >> end
> >> >> >>
> >> >> >> RestClient.put "#{DB}/_design/test", < >> >> >> {
> >> >> >> "views":{
> >> >> >> "one":{
> >> >> >> "map":"function (doc) { emit(doc.x,null); }"
> >> >> >> }
> >> >> >> }
> >> >> >> }
> >> >> >> EOS
> >> >> >>
> >> >> >> puts RestClient.get("#{DB}/_design/test/_view/one")
> >> >> >> ----
> >> >> >>
> >> >> >> This shows the collation sequence to be as follows.
> >> >> >>
> >> >> >> {"total_rows":95,"offset":0,"rows":[
> >> >> >> {"id":"20","key":" ","value":null},
> >> >> >> {"id":"60","key":"`","value":null},
> >> >> >> {"id":"5e","key":"^","value":null},
> >> >> >> {"id":"5f","key":"_","value":null},
> >> >> >> {"id":"2d","key":"-","value":null},
> >> >> >> {"id":"2c","key":",","value":null},
> >> >> >> {"id":"3b","key":";","value":null},
> >> >> >> {"id":"3a","key":":","value":null},
> >> >> >> {"id":"21","key":"!","value":null},
> >> >> >> {"id":"3f","key":"?","value":null},
> >> >> >> {"id":"2e","key":".","value":null},
> >> >> >> {"id":"27","key":"'","value":null},
> >> >> >> {"id":"22","key":"\"","value":null},
> >> >> >> {"id":"28","key":"(","value":null},
> >> >> >> {"id":"29","key":")","value":null},
> >> >> >> {"id":"5b","key":"[","value":null},
> >> >> >> {"id":"5d","key":"]","value":null},
> >> >> >> {"id":"7b","key":"{","value":null},
> >> >> >> {"id":"7d","key":"}","value":null},
> >> >> >> {"id":"40","key":"@","value":null},
> >> >> >> {"id":"2a","key":"*","value":null},
> >> >> >> {"id":"2f","key":"/","value":null},
> >> >> >> {"id":"5c","key":"\\","value":null},
> >> >> >> {"id":"26","key":"&","value":null},
> >> >> >> {"id":"23","key":"#","value":null},
> >> >> >> {"id":"25","key":"%","value":null},
> >> >> >> {"id":"2b","key":"+","value":null},
> >> >> >> {"id":"3c","key":"<","value":null},
> >> >> >> {"id":"3d","key":"=","value":null},
> >> >> >> {"id":"3e","key":">","value":null},
> >> >> >> {"id":"7c","key":"|","value":null},
> >> >> >> {"id":"7e","key":"~","value":null},
> >> >> >> {"id":"24","key":"$","value":null},
> >> >> >> {"id":"30","key":"0","value":null},
> >> >> >> {"id":"31","key":"1","value":null},
> >> >> >> {"id":"32","key":"2","value":null},
> >> >> >> {"id":"33","key":"3","value":null},
> >> >> >> {"id":"34","key":"4","value":null},
> >> >> >> {"id":"35","key":"5","value":null},
> >> >> >> {"id":"36","key":"6","value":null},
> >> >> >> {"id":"37","key":"7","value":null},
> >> >> >> {"id":"38","key":"8","value":null},
> >> >> >> {"id":"39","key":"9","value":null},
> >> >> >> {"id":"61","key":"a","value":null},
> >> >> >> {"id":"41","key":"A","value":null},
> >> >> >> {"id":"62","key":"b","value":null},
> >> >> >> {"id":"42","key":"B","value":null},
> >> >> >> {"id":"63","key":"c","value":null},
> >> >> >> {"id":"43","key":"C","value":null},
> >> >> >> {"id":"64","key":"d","value":null},
> >> >> >> {"id":"44","key":"D","value":null},
> >> >> >> {"id":"65","key":"e","value":null},
> >> >> >> {"id":"45","key":"E","value":null},
> >> >> >> {"id":"66","key":"f","value":null},
> >> >> >> {"id":"46","key":"F","value":null},
> >> >> >> {"id":"67","key":"g","value":null},
> >> >> >> {"id":"47","key":"G","value":null},
> >> >> >> {"id":"68","key":"h","value":null},
> >> >> >> {"id":"48","key":"H","value":null},
> >> >> >> {"id":"69","key":"i","value":null},
> >> >> >> {"id":"49","key":"I","value":null},
> >> >> >> {"id":"6a","key":"j","value":null},
> >> >> >> {"id":"4a","key":"J","value":null},
> >> >> >> {"id":"6b","key":"k","value":null},
> >> >> >> {"id":"4b","key":"K","value":null},
> >> >> >> {"id":"6c","key":"l","value":null},
> >> >> >> {"id":"4c","key":"L","value":null},
> >> >> >> {"id":"6d","key":"m","value":null},
> >> >> >> {"id":"4d","key":"M","value":null},
> >> >> >> {"id":"6e","key":"n","value":null},
> >> >> >> {"id":"4e","key":"N","value":null},
> >> >> >> {"id":"6f","key":"o","value":null},
> >> >> >> {"id":"4f","key":"O","value":null},
> >> >> >> {"id":"70","key":"p","value":null},
> >> >> >> {"id":"50","key":"P","value":null},
> >> >> >> {"id":"71","key":"q","value":null},
> >> >> >> {"id":"51","key":"Q","value":null},
> >> >> >> {"id":"72","key":"r","value":null},
> >> >> >> {"id":"52","key":"R","value":null},
> >> >> >> {"id":"73","key":"s","value":null},
> >> >> >> {"id":"53","key":"S","value":null},
> >> >> >> {"id":"74","key":"t","value":null},
> >> >> >> {"id":"54","key":"T","value":null},
> >> >> >> {"id":"75","key":"u","value":null},
> >> >> >> {"id":"55","key":"U","value":null},
> >> >> >> {"id":"76","key":"v","value":null},
> >> >> >> {"id":"56","key":"V","value":null},
> >> >> >> {"id":"77","key":"w","value":null},
> >> >> >> {"id":"57","key":"W","value":null},
> >> >> >> {"id":"78","key":"x","value":null},
> >> >> >> {"id":"58","key":"X","value":null},
> >> >> >> {"id":"79","key":"y","value":null},
> >> >> >> {"id":"59","key":"Y","value":null},
> >> >> >> {"id":"7a","key":"z","value":null},
> >> >> >> {"id":"5a","key":"Z","value":null}
> >> >> >> ]}
> >> >> >>
> >> >> >> I've never seen this sequence before. It's not even EBCDIC :-)
> >> >> >>
> >> >> >> Adding aa into the pot gives:
> >> >> >>
> >> >> >> ...
> >> >> >> {"id":"61","key":"a","value":null},
> >> >> >> {"id":"41","key":"A","value":null},
> >> >> >> {"id":"X","key":"aa","value":null},
> >> >> >> ...
> >> >> >>
> >> >> >> As you say, that is most bizarre.
> >> >> >>
> >> >> >> Cheers,
> >> >> >>
> >> >> >> Brian.
> >> >> >>
> >> >> >
> >> >>
> >> >
> >>
> >
>