Matching beginning of words in a NSString - iphone

Is there a method built in to NSString that tokenizes the string and searches the beginning of each token? the compare method seems to only do the beginning of a string, and using rangeOfString isn't really sufficient because it doesn't have knowledge of tokens. Right now I'm thinking the best way to do this is to call
[myString componentsSeparatedByString:#" "]
and then loop over the resulting array, calling compare on each component of the string. Is this built-in and I just missed it?

Using CFStringTokenizer for, um, tokenizing strings will be more robust than splitting on #" ", but searching the results is still left up to you.

You may want to look into RegexKit Lite:
http://regexkit.sourceforge.net/#RegexKitLite/
Although it's a third party library, it's basically a very small (one class) wrapper built around the built-in fairly powerful regular expression engine.
It seems like this would be more useful since you could have non-capturing expressions match around the token-separators and then the capturing portion include or not include the text you are looking for along with the remaining text between tokens. If you have not used regular expressions much before, you'll want to read some kind of reference but just be aware you can separate out matching patterns from content you want to see with a cryptic but very powerful syntax.
I'm also not sure you can use CFStringTokenizer on the iPhone since the iPhone specific doc set has no reference for it.

Related

Multiple regex in one command

Disclaimer: I have no engineering background whatsoever - please don't hold it against me ;)
What I'm trying to do:
Scan a bunch of text strings and find the ones that
are more than one word
contain title case (at least one capitalized word after the first one)
but exclude specific proper nouns that don't get checked for title case
and disregard any parameters in curly brackets
Example: Today, a Man walked his dogs named {FIDO} and {Fifi} down the Street.
Expectation: Flag the string for title capitalization because of Man and Street, not because of Today, {FIDO} or {Fifi}
Example: Don't post that video on TikTok.
Expectation: No flag because TikTok is a proper noun
I have bits and pieces, none of them error-free from what https://www.regextester.com/ keeps telling me so I'm really hoping for help from this community.
What I've tried (in piece meal but not all together):
(?=([A-Z][a-z]+\s+[A-Z][a-z]+))
^(?!(WordA|WordB)$)
^((?!{*}))
I think your problem is not really solvable solely with regex...
My recommendation would be splitting the input via [\s\W]+ (e.g. with python's re.split, if you really need strings with more than one word, you can check the length of the result), filtering each resulting word if the first character is uppercase (e.g with python's string.isupper) and finally filtering against a dictionary.
[\s\W]+ matches all whitespace and non-word characters, yielding words...
The reasoning behind this different approach: compiling all "proper nouns" in a regex is kinda impossible, using "isupper" also works with non-latin letters (e.g. when your strings are unicode, [A-Z] won't be sufficient to detect uppercase). Filtering utilizing a dictionary is a way more forward approach and much easier to maintain (I would recommend using set or other data type suited for fast lookups.
Maybe if you can define your use case more clearer we can work out a pure regex solution...

REST pattern for for query parameters that might be LIKE searches

Hi I'm building a RESTful app and can't find the recommended way to pattern optional fuzzy or LIKE queries. For example a strict query might be,
/place?city=New+York&state=NY
Corresponds to SQL "... WHERE city="New York" AND state="NY"
But what if I wanted to search for the city field for any row with "York" in city name?
"... WHERE city LIKE "%{parameter}%" AND state="{parameter2}"
I'm thinking about just adding some kind of url-valid character to the request like this:
/place?city=*York*&state=NY
Is there an established or recommended pattern I should use? Thanks!
It's fine to use query string for searching, but it's a little bit weird to use macro character like "*" or "?" in query string(unless you decide to build a really powerful search engine like Google). More importantly, search is usually considered in fuzzy mode by default, so it's redundant to append/prepend the keyword with "*". If you do need exact search, you could surround the exact(or strict) keyword with double quotes. Namely, instead of using /place?city=*York*&state=NY, I recommend /place?city=York&state="NY".
In fact, Google uses quotes to search for an exact word or set of words, and I also found this site takes this pattern.

Count the number of words in NSString

I'm trying to implement a word count function for my app that uses UITextView.
There's a space between two words in English, so it's really easy to count the number of words in an English sentence.
The problem occurs with Chinese and Japanese word counting because usually, there's no any space in the entire sentence.
I checked with three different text editors in iPad that have a word count feature and compare them with MS Words.
For example, here's a series of Japanese characters meaning the world's idea: 世界(the world)の('s)アイデア(idea)
世界のアイデア
1) Pages for iPad and MS Words count each character as one word, so it contains 7 words.
2) iPad text editor P*** counts the entire as one word --> They just used space to separate words.
3) iPad text editor i*** counts them as three words --> I believe they used CFStringTokenizer with kCFStringTokenizerUnitWord because I could get the same result)
I've researched on the Internet, and Pages and MS Words' word counting seems to be correct because each Chinese character has a meaning.
I couldn't find any class that counts the words like Pages or MS Words, and it would be very hard to implement it from scratch because besides Japanese and Chinese, iPad supports a lot of different foreign languages.
I think CFStringTokenizer with kCFStringTokenizerUnitWord is the best option though.
Is there a way to count words in NSString like Pages and MSWords?
Thank you
I recommend keep using CFStringTokenizer. Because it's platform feature, so will be upgraded by platform upgrade. And many people in Apple are working hardly to reflect real cultural difference. Which are hard to know for regular developers.
This is hard because this is not a programming problem essentially. This is a human cultural linguistic problem. You need a human language specialist for each culture. For Japanese, you need Japanese culture specialist. However, I don't think Japanese people needs word count feature seriously, because as I heard, the concept of word itself is not so important in the Japanese culture. You should define concept of word first.
And I can't understand why you want to force concept of word count into the character count. The Kanji word that you instanced. This is equal with counting universe as 2 words by splitting into uni + verse by meaning. Not even a logic. Splitting word by it's meaning is sometimes completely wrong and useless by the definition of word. Because definition of word itself are different by the cultures. In my language Korean, word is just a formal unit, not a meaning unit. The idea that each word is matching to each meaning is right only in roman character cultures.
Just give another feature like character counting for the users in east-asia if you think need it. And counting character in unicode string is so easy with -[NSString length] method.
I'm a Korean speaker, (so maybe out of your case :) and in many cases we count characters instead of words. In fact, I never saw people counting words in my whole life. I laughed at word counting feature on MS word because I guessed nobody would use it. (However now I know it's important in roman character cultures.) I have used word counting feature only once to know it works really :) I believe this is similar in Chinese or Japanese. Maybe Japanese users use the word counting because their basic alphabet is similar with roman characters which have no concept of composition. However they're using Kanji heavily which are completely compositing, character-centric system.
If you make word counting feature works greatly on those languages (which are using by people even does not feel any needs to split sentences into smaller formal units!), it's hard to imagine someone who using it. And without linguistic specialist, the feature should not correct.
This is a really hard problem if your string doesn't contain tokens identifying word breaks (like spaces). One way I know derived from attempting to solve anagrams is this:
At the start of the string you start with one character. Is it a word? It could be a word like "A" but it could also be a part of a word like "AN" or "ANALOG". So the decision about what is a word has to be made considering all of the string. You would consider the next characters to see if you can make another word starting with the first character following the first word you think you might have found. If you decide the word is "A" and you are left with "NALOG" then you will soon find that there are no more words to be found. When you start finding words in the dictionary (see below) then you know you are making the right choices about where to break the words. When you stop finding words you know you have made a wrong choice and you need to backtrack.
A big part of this is having dictionaries sufficient to contain any word you might encounter. The English resource would be TWL06 or SOWPODS or other scrabble dictionaries, containing many obscure words. You need a lot of memory to do this because if you check the words against a simple array containing all of the possible words your program will run incredibly slow. If you parse your dictionary, persist it as a plist and recreate the dictionary your checking will be quick enough but it will require a lot more space on disk and more space in memory. One of these big scrabble dictionaries can expand to about 10MB with the actual words as keys and a simple NSNumber as a placeholder for value - you don't care what the value is, just that the key exists in the dictionary, which tells you that the word is recognised as valid.
If you maintain an array as you count you get to do [array count] in a triumphal manner as you add the last word containing the last characters to it, but you also have an easy way of backtracking. If at some point you stop finding valid words you can pop the lastObject off the array and replace it at the start of the string, then start looking for alternative words. If that fails to get you back on the right track pop another word.
I would proceed by experimentation, looking for a potential three words ahead as you parse the string - when you have identified three potential words, take the first away, store it in the array and look for another word. If you find it is too slow to do it this way and you are getting OK results considering only two words ahead, drop it to two. If you find you are running up too many dead ends with your word division strategy then increase the number of words ahead you consider.
Another way would be to employ natural language rules - for example "A" and "NALOG" might look OK because a consonant follows "A", but "A" and "ARDVARK" would be ruled out because it would be correct for a word beginning in a vowel to follow "AN", not "A". This can get as complicated as you like to make it - I don't know if this gets simpler in Japanese or not but there are certainly common verb endings like "ma su".
(edit: started a bounty, I'd like to know the very best way to do this if my way isn't it.)
If you are using iOS 4, you can do something like
__block int count = 0;
[string enumerateSubstringsInRange:range
options:NSStringEnumerationByWords
usingBlock:^(NSString *word,
NSRange wordRange,
NSRange enclosingRange,
BOOL *stop)
{
count++;
}
];
More information in the NSString class reference.
There is also WWDC 2010 session, number 110, about advanced text handling, that explains this, around minute 10 or so.
I think CFStringTokenizer with kCFStringTokenizerUnitWord is the best option though.
That's right, you have to iterate through text and simply count number of word tokens encontered on the way.
Not a native chinese/japanese speaker, but here's my 2cents.
Each chinese character does have a meaning, but concept of a word is combination of letters/characters to represent an idea, isn't it?
In that sense, there's probably 3 words in "sekai no aidia" (or 2 if you don't count particles like NO/GA/DE/WA, etc). Same as english - "world's idea" is two words, while "idea of world" is 3, and let's forget about the required 'the' hehe.
That given, counting word is not as useful in non-roman language in my opinion, similar to what Eonil mentioned. It's probably better to count number of characters for those languages.. Check around with Chinese/Japanese native speakers and see what they think.
If I were to do it, I would tokenize the string with spaces and particles (at least for japanese, korean) and count tokens. Not sure about chinese..
With Japanese you can create a grammar parser and I think it is the same with Chinese. However, that is easier said than done because natural language tends to have many exceptions, but it is not impossible.
Please note it won't really be efficient since you have to parse each sentence before being able to count the words.
I would recommend the use of a parser compiler rather than building one yourself as well to start at least you can concentrate on doing the grammar than creating the parser yourself. It's not efficient, but it should get the job done.
Also have a fallback algorithm in case your grammar didn't parse the input correctly (perhaps the input really didn't make sense to begin with) you can use the length of the string to make it easier on you.
If you build it, there could be a market opportunity for you to use it as a natural language Domain Specific Language for Japanese/Chinese business rules as well.
Just use the length method:
[#"世界のアイデア" length]; // is 7
That being said, as a Japanese speaker, I think 3 is the right answer.

regex to get string within 2 strings

"artistName":"Travie McCoy", "collectionName":"Billionaire (feat. Bruno Mars) - Single", "trackName":"Billionaire (feat. Bruno Mars)",
i wish to get the artist name so Travie McCoy from within that code using regex, please not i am using regexkitlite for the iphone sdk if this changes things.
Thanks
"?artistName"?\s*:\s*"([^"]*)("|$) should do the trick. It even handles some variations in the string:
White space before and after the :
artistName with and without the quotes
missing " at the end of the artist name if it is the last thing on the line
But there will be many more variations in the input you might encounter that this regex will not match.
Also you don’t want to use a regex for matching this for performance reasons. Right now you might only be interested in the artistName field. But some time later you will want information from the other fields. If you just change the field name in the regex you’ll have to match the whole string again. Much better to use a parser and transform the whole string into a dictionary where you can access the different fields easily. Parsing the whole string shouldn’t take much longer than matching the last key/value pair using a regex.
This looks like some kind of JSON, there are lots of good and complete parsers available. It isn’t hard to write one yourself though. You could write a simple recursive descent parser in a couple of hours. I think this is something every programmer should have done at least once.
\"?artistName\"?\s*:\s*\"([^\"]*)(\"|$)
Thats for objective c

Search or compare within a Grapheme Cluster in Korean

In my current implementation of a UISearchBarController I'm using [NSString compare:] inside the filterContentForSearchText:scope: delegate method to return relevant objects based on their name property to the results UITableView as you start typing.
So far this works great in English and Korean, but what I'd like to be able to do is search within NSString's defined character clusters. This is only applicable for a handfull of languages, of which Korean is one.
In English, compare: returns new results after every letter you enter, but in Korean the results are generated once you complete a recognized grapheme cluster. I would like to be able to search through my Korean objects name property via the individual elements that make up a syllable.
Can anyone shed any light on how to approach this? I'm sure it has something to do with searching through UTF16 characters manually, or by utilising a lower level class.
Cheers!
Here is a specific example that's just not working:
`NSString *string1 = #"이";
`NSString *string2 = #"ㅣ";
NSRange resultRange = [[string1 decomposedStringWithCanonicalMapping] rangeOfString: [string2 decomposedStringWithCanonicalMapping] options:(NSLiteralSearch)];
The result is always NSNotFound, with or without decomposedStringWithCanonicalMapping.
Any ideas?
I'm no expert, but I think you're very unlikely to find a clean solution for what you want. There doesn't seem to be any relationship between a Korean character's Unicode value and the graphemes that it's made up of.
e.g. "이" is \uc774 and "ㅣ" is \u3163. From the perspective of the NSString, they're just two different characters with no specific relationship to each other.
I suspect that you will have to find or create an explicit mapping between characters and their graphemes, and then write your own search function that consults this mapping.
This very long page on Unicode Korean can help you, if it comes to that. It has a table of all the characters which suggests some structured relation between the way characters are numbered and their components.
If you use compare:options with NSLiteralString, it should compare character by character, that is, the Unicode code points, regardless of the grapheme. The default behavior of compare: is to use no options. You could use - decomposedStringWithCanonicalMapping to get the Unicode bytes of the input string, but I'm not sure how that would interact with compare:.