I want to do a query that matches anything containing the characters 0xFB50-0xFDFF (Arabic Presentation Forms-A) and 0xFE70-0xFEFF (Arabic Presentation Forms-B). I have tried various things, including simple REGEXP with those characters enclosed in [] with a dash in the middle (e.g., [ݐ-ݭ]) but it seems to return everything with Arabic in it, even if it's not in the "presentation form" range. I was wondering if there was something like:
SELECT column FROM db WHERE CHAR(0xFE70) THROUGH CHAR(0xFEFF);
Obviously there is no "through" operator, but that's my pseudo-code :)
Thanks!
Found the answer from another article here. I decided MySQL's regex engine was not clever enough to do what I wanted to natively, so I used the PCRE functionality of PHP...
$arabic_presentation_forms = "[\x{fb50}-\x{feff}]";
preg_match("/$arabic_presentation_forms/u",$db_output);
Worked well.
Related
I know that Hebrew and Arabic characters are going from right to left but I want to see all of them.
Have a look at the bidirectional character type (Unicode character property Bidi_Class). You're looking for characters of type R (Right-to-Left) or AL (Right-to-Left Arabic). The file DerivedBidiClass.txt in the Unicode database contains a list of all code points with these classes.
Quoting i18nguy:
Languages don't have a direction. Scripts have a writing direction,
and so languages written in a particular script, will be written with
the direction of that script.
Here are some scripts using RTL: Arabic, Hebrew, N'ko, Syriac, Thaana/Thâna, Tifinar, Urdu.
You can just look for unicode range of a given script. Like for example Tifinar: U+2D30 – U+2D7F.
Not sure what you want to achieve by looking at all those characters but I think that is the only way of actually finding them.
You can refer to the original page here:
http://www.i18nguy.com/temp/rtl.html
What would be a good Lucene analyzer to use for documents that are a mix of text and diverse source code?
For example, I want "C" and "C++" to be considered different words, and I want Charset.forName("utf-8") to be split between the class name and method name, and for the parameter to be considered either one or two words.
A good example dataset for what I'd like to look at is StackOverflow itself. I believe that StackOverflow uses Lucene.NET for search; does it use a stock analyzer, or has it been heavily customized?
You're probably best to use the WhitespaceTokenizer and customize it to strip off punctuation. For example we strip of all puncutation except '+', '-' so that words such as C++, etc... are left but opening and closing quotes and brackets, etc are left. In reality though for something like this you might have to add the document twice using different tokenizers to catch the different parts of the document. i.e. once with the StandardTokenizer and once with a WhitespaceTokenizer, in this case the StandardTokenizer will split all your code, e.g. between class and method names as the Whitespace one will pick-up the words such as C++. Obviously it kind of depends on the language though as e.g. Scala allows some punctuation characters in method names.
now before you prepare to right a speech about the perils of HTML parsing with regex, I already know it. This is more just a curiosity question, than actually wanting to know the question for practical usage.
Basically, given a file of HTML in some random, but perfectly valid format, can you parse out the content of <p> tags using a half-sane number of regular expressions? (and also pretending that <p> tags can not be nested or some other minor limitation)
It's certainly possible to extract all the text between {insert character sequence 1 here} and {insert character sequence 2 here} with regular expressions, so long as those sequences aren't overlapping. For example:
/(?<{insert character sequence 1 here}).*?(?={insert character sequence 2 here})/
Of course, it's terribly brittle and will break horribly if what you're running it on is even slightly malformed, or contains either character sequence outside the context where it's meaningful, or any number of other ways. If you oversimplify the problem, then yes you can get away with an oversimplified solution.
Yes, under restrictions like valid HTML and non-nesting, you can use regular expressions for certain uses.
It depends on what you limitations you'd consider minor. XHTML, for one obvious example, is somewhat more amenable to simple parsing. A great deal depends on whether you're thinking in terms of parsing existing HTML, or generating new HTML that could be parsed relatively easily. For the former case, I'd say the restrictions were major -- i.e., you'd need to know a great deal about the specific HTML in question to parse it. For the latter case, I'd say the restrictions were fairly trivial -- i.e., would only involve how you write the HTML, but would not affect what you could express in HTML.
I'd like to HTML escape a specific phrase automatically and logically that is currently a statement with words highlighted with quotation marks. Within the statement, quotation or inch marks could also be used to describe a distance.
The phrase could be:
Paul said "It missed us by about a foot". In fact it was only about 9".
To escape this phrase It should really be
<pre>Paul said “It missed us by about a foot”.
In fact it was only about 9′.</pre>
Which gives
<pre>Paul said “It missed us by about a foot”.
In fact it was only about 9″.</pre>
I can't think of a sample phrase to add in a " escape as well but that could be there!
I'm looking for some help on how to identify which of the escape values to replace " characters with at runtime. The phrase was just an example and it could be anything but should be correctly formed i.e. an opening and closing quote would be present if we are to correctly escape the text.
Would I use a regular expression to find a quoted phrase in the text i.e. two " " characters before a full stop and then replace the first then the second. with
“
then
”
If I found one " replace it with a
"
unless it was after a number where I replace it with
″
How would I deal with multiple quotes within a sentence?
"It just missed" Paul said "by a foot".
This would really stump me.....
<pre>"It just missed" Paul said "by 9" almost".</pre>
The above should read when escaped correctly. (I'm showing the actual characters this time)
“It just missed” Paul said “by 9″ almost”.
Obviously an edge case but I wondered if it's possible to escape this at runtime without an understanding of the content? If not help on the more obvious phrases would be appreciated.
I would do this in two passes:
The first pass searches for any "s which are immediately preceded by numbers and does that replacement:
s/([0-9])"/\1″/g
Depending on the text you're dealing with, you may want/need to extend this regex to also recognize numbers that are spelled out as words; I've only checked for digits for the sake of simplicity.
With all of those taken care of, a second pass can then easily convert pairs of "s as you've described:
s/"([^"]*)"/“\1”/g
Note the use of [^"]* rather than .* - we want to find two sets of double-quotes with any number of non-double-quote characters between them. By adding that restriction, there won't be any problems handling strings with multiple quoted sections. (This could also be accomplished using the non-greedy .*?, but a negated character class more clearly states your intent and, in most regex implementations, is more efficient.)
A stray, mismatched " somewhere in the string, or an inch marker which is missed by the first pass, can still cause problems, of course, but there's no way to avoid that possibility without implementing understanding of the content.
what you've described is basically a hidden markov model,
http://en.wikipedia.org/wiki/Hidden_Markov_model
you have a set of input symbols (your original text and ambiguous punctuation), and a set of output symbols (original text and more fine-grained punctuation) but no good way of really observing the connection between the two in a programmatic way. you could write some rules to cover some of the edge cases, but that will basically never work for the multiple quotes situation. in this case you can't really use a regex for the same reason, but with an hmm, and a bunch of training text you could probably mmake some pretty good guesses.
sorry that's probably not very helpful if you're trying to get something ready for deployment, but the input has greater ambiguity than the output, so your only option is to consider the context, and that basically means either a very lengthy set of rules, or some kind of machine learning approach.
interesting question though - it would be neat to see what kind of performance you could get. maybe someone's already written a paper on it?
I wondered if it's possible to escape
this at runtime without an
understanding of the content?
Considering that you're adding semantic meaning to the punctuation which is currently encoded in the other text... no, not really.
Regular expressions would be the easiest tool for at least part of it. I'd suggest looking for /\d+"/ for the inch number cases. But for quotes delimiters, after you'd looked for any other special cases or phrases, it may be easier to use an algorithm for matching pairs, like with parentheses and brackets: tokenize and count. Then test on real-world input and refine.
But I really have to ask: why?
I am not sure if it is possible at all to do that without understanding the meaning of the sentence. I tend to doubt it.
My first attempt would be the following.
go from left to right through the string
alternate replacing double primes with left and right double quotes, but replace with double primes if there is a number to the left
if the quotation marks are unbalanced at the end of the string go back until you find a number with double primes and change the double primes into left or right double quotes depending on the preceding double quotes.
I am quite sure that you can easily fail this strategy. But it is still the easy case - hard work starts when you have to deal with nested quotation marks.
I know this is off the wall, but have you considered Mechanical Turk? This is the sort of problem humans excel at, and computers, currently, are terrible at. Choosing the correct punctuation requires understanding of the meaning of the sentence, so a regex is bound to fail for edge cases.
You could try something like this. First replace the quotations with this regular expression:
"((?:[^"\d]+|\d"?)*)"
And than the inch sign:
(\d+)"
Here’s an example in JavaScript:
'"It just missed" Paul said "by 9" almost"'.replace(/"((?:[^"\d]*|\d["']?)+)"/g, "“$1”").replace(/(\d+)"/g, "$1″");
I have a txt file which actually is a html source of some webpage.
Inside that txt file there are various strings preceded by a "title=" tag.
e.g.
<div id='UWTDivDomains_5_6_2_2' title='Connectivity Framework'>
I am interested in getting the text Connectivity Framework to be extraced and written to a separate file.
Like this, there are many such tags each having a different text after the title='some text here which i need to extract '
I want to extract all such instances of the text from the html source/txt file and write to a separate txt file. The text can contain lower case, upper case letters and number only. The length of each text string(in characters) will vary.
I am using PowerGrep for windows. Powergrep allows me to search a text file with regular expression inout.
I tried using the search as
title='[a-zA-Z0-9]
It shows the correct matches, but it matches only first character of the string and writes only the first character of the text string matched to the second txt file, not all string.
I want all string to be matched and written to the second file.
What is the correct regular expression or way to do what i want to do, using powergrep?
-AD.
I'm just not sure how many times the question of regular expression parsing of HTML files has to be asked (and answered with the correct solution of "use a DOM parser"). It comes up every day.
The difficulties are:
In HTML attributes can have single-quotes, double-quotes or even no quotes;
Similar strings can appear in the HTML document itself;
You have to handle correct escaping; and
Malformed HTML (decent parsers are extremely robust to common errors).
So if you cater for all this (and it gets to be a pretty complicated yet still imperfect regex), it's still not 100%.
HTML parsers exist for a reason. Use them.
I'm not familiar with PowerGrep, however, your regex is incomplete. Try this:
title='[a-zA-Z0-9 ]*'
or better yet:
title='([^']*)'
The other answers all give correct changes to the regex, so I'll explain what the issue was with your original.
The square brackets indicate a character class - meaning that the regex will match any character within those brackets. However, like everything else, it will only match it once by default. Just as the regex "s" would match only the first character in "ssss", the regex "[a-zA-Z0-9]" will match only the first character in "Connectivity Framework".
By adding repetition, one can get that character class to match repeatedly. The easiest way to do this is by adding an asterisk after it (which will match 0 or more occurences). Thus the regex "[a-zA-Z0-9]*" will match as many characters in a row until it hits a character that is not in that character class (in your case, the space character since you didn't include that in your brackets).
Regexes though can be pretty complex to describe the syntax accurately - what if someone put a non-alphanumeric character such as an ampersand within the attribute? You could try to capture all input between the quotes by making the character set "anything except a quote character", so "'[^']*'" would usually do the right thing. Often you need to bear in mind escaping as well (e.g. with a string 'Mary\'s lamb' you do actually want to capture the apostrophe in the middle so a simple "everything but apostrophes" character set won't cut it) though thankfully this is not an issue with XML/HTML according to the specs.
Still, if there is an existing library available that will do the extraction for you, this is likely to be faster and more correct than rolling your own, so I would lean towards that if possible.
I would use this regular expression to get the title attribute values
<[a-z]+[^>]*\s+title\s*=\s*("[^"]*"|'[^']*'|[^\s >]*)
Note that this regex matches the attribute value expression with quotes. So you have to remove them if needed.
Here's the regex you need
title='([a-zA-Z0-9]+)'
but if you're going to be doing a lot more stuff like this, using a parser might make it much more robust and useful.
Try this instead:
title=\'[a-zA-Z0-9]*\'