I'm unable to find a good answer of how couchdb determines it's sort order in views. I thought it would be in ASCII order or be similar to javascript's sort function which converts everything to UTF-16 strings and compares based off of their byte values. However, I was a bit shocked to find that with the following view:
(doc) => {
emit("a",null)
emit("b",null)
emit("A",null)
emit("B",null)
}
the keys are not sorted ["A","B","a","b"] as what Array.prototype.sort produces but rather ["a","A","b","B"]. What is the implementation of the sort order that couchdb uses?
This is explained thoroughly in the CouchDB documentation 3.2.2.5. Collation Specification
Comparison of strings is done using ICU which implements the Unicode Collation Algorithm, giving a dictionary sorting of keys. This can give surprising results if you were expecting ASCII ordering.
Emphasis mine
A thorough read of that section should give anyone a solid grasp of the collation rules.
Related
I have a ruby project where part of the operation is to select entities given user-specified constraints. So far, I've been hacking my own filter language, using regular expressions and specifying inclusion/exclusion based on the fields in the entities.
If you are interested in my current approach, here's an example: For instance, given this list of entities:
[{"type":"dog", "name":"joe"}, {"type":"dog", "name":"fuzz"}, {"type":"cat", "name":"meow"}]
A user could specify a filter like so:
{"filter":{
"type":{"included":["dog"] },
"name":{"excluded":["^f.*"] }
}}
Would match all dogs but exclude fuzz.
This is sort of working now. However, I am starting to require more sophisticated selection parameters. I am thinking that rather than continuing to hack on my own filter language, there might be a more general-purpose filter language I can just embed in my application? For instance, is there a parser that can in-app filter using a SQL where clause? Or are there some other general, simple filter languages that I'm not aware of? I would especially like to move away from regexps since I want to do range querying on numbers (like is entity["size"] < 50 ?)
It is a little bit of an extrapolation, but I think you may be looking for a search engine, or at least enough of one that you may as well use one just for the query language.
If so you might want to look at elasticsearch which does have Ruby client bindings, and could be a good fit for what you are trying to do. Especially if you want or need to express the data you want to search as JSON for use by client code, as that format is natively supported by the search engine.
The query language is quite expressive, and there are a variety of built-in and plugin tools available to explore and use it.
in the end, i ended up implementing a ruby dsl. it's easy, fun, and powerful.
We have a large C# application using the GTK# bindings. Recently we became aware of a very strange bug: When the user clicks on a column to sort it, it doesn't sort correctly. To be specific, GTK appears to be ignoring all punctuation (including whitespace) and sorting only on alphabetic characters.
Does anybody have any idea why on Earth it would do something like that?
We're not doing anything fancy with custom sorting or anything like that. I'm really puzzled as to why it doesn't just sort the strings in ASCII order.
We eventually solved this by adding a custom sorting function that just does a normal ASCII comparison.
I'm still baffled as to why this doesn't happen by default in the first place... so if anybody knows, write your answer here.
I've recently discovered, to my astonishment (having never really thought about it before), machine-sorting Japanese proper nouns is apparently not possible.
I work on an application that must allow the user to select a hospital from a 3-menu interface. The first menu is Prefecture, the second is City Name, and the third is Hospital. Each menu should be sorted, as you might expect, so the user can find what they want in the menu.
Let me outline what I have found, as preamble to my question:
The expected sort order for Japanese words is based on their pronunciation. Kanji do not have an inherent order (there are tens of thousands of Kanji in use), but the Japanese phonetic syllabaries do have an order: あ、い、う、え、お、か、き、く、け、こ... and on for the fifty traditional distinct sounds (a few of which are obsolete in modern Japanese). This sort order is called 五十音順 (gojuu on jun , or '50-sound order').
Therefore, Kanji words should be sorted in the same order as they would be if they were written in hiragana. (You can represent any kanji word in phonetic hiragana in Japanese.)
The kicker: there is no canonical way to determine the pronunciation of a given word written in kanji. You never know. Some kanji have ten or more different pronunciations, depending on the word. Many common words are in the dictionary, and I could probably hack together a way to look them up from one of the free dictionary databases, but proper nouns (e.g. hospital names) are not in the dictionary.
So, in my application, I have a list of every prefecture, city, and hospital in Japan. In order to sort these lists, which is a requirement, I need a matching list of each of these names in phonetic form (kana).
I can't come up with anything other than paying somebody fluent in Japanese (I'm only so-so) to manually transcribe them. Before I do so though:
Is it possible that I am totally high on fire, and there actually is some way to do this sorting without creating my own mappings of kanji words to phonetic readings, that I have somehow overlooked?
Is there a publicly available mapping of prefecture/city names, from the government or something? That would reduce the manual mapping I'd need to do to only hospital names.
Does anybody have any other advice on how to approach this problem? Any programming language is fine--I'm working with Ruby on Rails but I would be delighted if I could just write a program that would take the kanji input (say 40,000 proper nouns) and then output the phonetic representations as data that I could import into my Rails app.
宜しくお願いします。
For Data, dig Google's Japanese IME (Mozc) data files here.
https://github.com/google/mozc/tree/master/src/data
There is lots of interesting data there, including IPA dictionaries.
Edit:
And you may also try Mecab, it can use IPA dictionary and can convert kanjis to katakana for most of the words
https://taku910.github.io/mecab/
and there is ruby bindings for that too.
https://taku910.github.io/mecab/bindings.html
and here is somebody tested, ruby with mecab with tagger -Oyomi
http://hirai2.blog129.fc2.com/blog-entry-4.html
just a quick followup to explain the eventual actual solution we used. Thanks to all who recommended mecab--this appears to have done the trick.
We have a mostly-Rails backend, but in our circumstance we didn't need to solve this problem on the backend. For user-entered data, e.g. creating new entities with Japanese names, we modified the UI to require the user to enter the phonetic yomigana in addition to the kanji name. Users seem accustomed to this. The problem was the large corpus of data that is built into the app--hospital, company, and place names, mainly.
So, what we did is:
We converted all the source data (a list of 4000 hospitals with name, address, etc) into .csv format (encoded as UTF-8, of course).
Then, for developer use, we wrote a ruby script that:
Uses mecab to translate the contents of that file into Japanese phonetic readings
(the precise command used was mecab -Oyomi -o seed_hospitals.converted.csv seed_hospitals.csv, which outputs a new file with the kanji replaced by the phonetic equivalent, expressed in full-width katakana).
Standardizes all yomikata into hiragana (because users tend to enter hiragana when manually entering yomikata, and hiragana and katakana sort differently). Ruby makes this easy once you find it: NKF.nkf("-h1 -w", katakana_str) # -h1 means to hiragana, -w means output utf8
Using the awesomely conveninent new Ruby 1.9.2 version of CSV, combine the input file with the mecab-translated file, so that the resulting file now has extra columns inserted, a la NAME, NAME_YOMIGANA, ADDRESS, ADDRESS_YOMIGANA, and so on.
Use the data from the resulting .csv file to seed our rails app with its built-in values.
From time to time the client updates the source data, so we will need to do this whenever that happens.
As far as I can tell, this output is good. My Japanese isn't good enough to be 100% sure, but a few of my Japanese coworkers skimmed it and said it looks all right. I put a slightly obfuscated sample of the converted addresses in this gist so that anybody who cared to read this far can see for themselves.
UPDATE: The results are in... it's pretty good, but not perfect. Still, it looks like it correctly phoneticized 95%+ of the quasi-random addresses in my list.
Many thanks to all who helped me!
Nice to hear people are working with Japanese.
I think you're spot on with your assessment of the problem difficulty. I just asked one of the Japanese guys in my lab, and the way to do it seems to be as you describe:
Take a list of Kanji
Infer (guess) the yomigana
Sort yomigana by gojuon.
The hard part is obviously step two. I have two guys in my lab: 高橋 and 高谷. Naturally, when sorting reports etc. by name they appear nowhere near each other.
EDIT
If you're fluent in Japanese, have a look here: http://mecab.sourceforge.net/
It's a pretty popular tool, so you should be able to find English documentation too (the man page for mecab has English info).
I'm not familiar with MeCab, but I think using MeCab is good idea.
Then, I'll introduce another method.
If your app is written in Microsoft VBA, you can call "GetPhonetic" function. It's easy to use.
see : http://msdn.microsoft.com/en-us/library/aa195745(v=office.11).aspx
Sorting prefectures by its pronunciation is not common. Most Japanese are used to prefectures sorted by 「都道府県コード」.
e.g. 01:北海道, 02:青森県, …, 13:東京都, …, 27:大阪府, …, 47:沖縄県
These codes are defined in "JIS X 0401" or "ISO-3166-2 JP".
see (Wikipedia Japanese) :
http://ja.wikipedia.org/wiki/%E5%85%A8%E5%9B%BD%E5%9C%B0%E6%96%B9%E5%85%AC%E5%85%B1%E5%9B%A3%E4%BD%93%E3%82%B3%E3%83%BC%E3%83%89
I'm looking for an algorithm that sorts strings similar to the way files (and folders) are sorted in Windows Explorer. It seems that numeric values in strings are taken into account when sorted which results in something like
name 1, name 2, name 10
instead of
name 1, name 10, name 2
which you get with a regular string comparison.
I was about to start writing this myself but wanted to check if anyone had done this before and was willing to share some code or insights. The way I would approach this would be to add leading zeros to the numeric values in the name before comparing them. This would result in something like
name 00001, name 00010, name 00002
which when sorted with a regular string sort would give me the correct result.
Any ideas?
It's called "natural sort order". Jeff had a pretty extensive blog entry on it a while ago, which describes the difficulties you might overlook and has links to several implementations.
Explorer uses the API StrCmpLogicalW() for this kind of sorting (called 'natural sort order').
You don't need to write your own comparison function, just use the one that already exists.
A good explanation can be found here.
There is StrCmpLogicalW, but it's only available starting with Windows XP and only implemented as Unicode.
Some background information:
http://www.siao2.com/2006/10/01/778990.aspx
The way I understood it, Windows Explorer sorts as per your second example - it's always irritated me hugely that the ordering comes out 1, 10, 2. That's why most apps which write lots of files (like batch apps) always use fixed length filenames with leading 0's or whatever.
Your solution should work, but you'd need to be careful where the numbers were in the filename, and probably only use your approach if they were at the very end.
Have a look at
http://www.interact-sw.co.uk/iangblog/2007/12/13/natural-sorting
for some source code.
I also posted a related question with additional hints and pitfalls:
Sorting strings is much harder than you thought
I posted code (C#) and a description of the algorithm here:
Natural Sort Order in C#
This is a try to implement it in Java:
Java - Sort Strings like Windows Explorer
In short it splits the two Strings to compare in Letter - Digit Parts and compares this parts in a specific way to achieve this kind of sorting.
Can you suggest some light weight fuzzy text search library?
What I want to do is to allow users to find correct data for search terms with typos.
I could use full-text search engines like Lucene, but I think it's an overkill.
Edit:
To make question more clear here is a main scenario for that library:
I have a large list of strings. I want to be able to search in this list (something like MSVS' intellisense) but it should be possible to filter this list by string which is not present in it but close enough to some string which is in the list.
Example:
Red
Green
Blue
When I type 'Gren' or 'Geen' in a text box, I want to see 'Green' in the result set.
Main language for indexed data will be English.
I think that Lucene is to heavy for that task.
Update:
I found one product matching my requirements. It's ShuffleText.
Do you know any alternatives?
Lucene is very scalable—which means its good for little applications too. You can create an index in memory very quickly if that's all you need.
For fuzzy searching, you really need to decide what algorithm you'd like to use. With information retrieval, I use an n-gram technique with Lucene successfully. But that's a special indexing technique, not a "library" in itself.
Without knowing more about your application, it won't be easy to recommend a suitable library. How much data are you searching? What format is the data? How often is the data updated?
I'm not sure how well Lucene is suited for fuzzy searching, the custom library would be better choice. For example, this search is done in Java and works pretty fast, but it is custom made for such task:
http://www.softcorporation.com/products/people/
Soundex is very 'English' in it's encoding - Daitch-Mokotoff works better for many names, especially European (Germanic) and Jewish names. In my UK-centric world, it's what I use.
Wiki here.
You didn't specify your development platform, but if its PHP then suggest you look at the ZEND Lucene lubrary :
http://ifacethoughts.net/2008/02/07/zend-brings-lucene-to-php/
http://framework.zend.com/manual/en/zend.search.lucene.html
As it LAMP its far lighter than Lucene on Java, and can easily be extended for other filetypes, provided you can find a conversion library or cmd line converter - there are lots of OSS solutions around to do this.
Try Walnutil - based on Lucene API - integrated to SQL Server and Oracle DBs . You can create any type of index and then use it. For simple search you can use some methods from walnutilsoft, for more complicated search cases you can use Lucene API. See web based example where was used indexes created from Walnutil Tools. Also you can see some code example written on Java and C# which you can use it for creating different type of search.
This tools is free.
http://www.walnutilsoft.com/
If you can choose to use a database, I recommend using PostgreSQL and its fuzzy string matching functions.
If you can use Ruby, I suggest looking into the amatch library.
#aku - links to working soundex libraries are right there at the bottom of the page.
As for Levenshtein distance, the Wikipedia article on that also has implementations listed at the bottom.
A powerful, lightweight solution is sphinx.
It's smaller then Lucene and it supports disambiguation.
It's written in c++, it's fast, battle-tested, has libraries for every env and it's used by large companies, like craigslists.org