Does anyone have a good regex for stripping all symbols (';.,_\$#!% the carriage return etc) from a string, without damaging any foreign characters (é 多 فا etc)? Non-regex would be even better, I suppose, but I don't see any Ruby or Rails methods that do this.
What is a symbol? This seems like a fuzzy requirement. Is & a symbol, even though it's just shorthand for the word "and"? Is ! a symbol, even though it's used as an alphabetic character in transliterating some African languages? If $ is a symbol, does that mean 円 is as well? I think answering this question will go a long way to suggesting a course of action.
I think the closest you are likely to get with a regexp is /[^\w\s]/. Ruby 1.9's Regexp engine is meant to understand foreign languages well enough to correctly know which are "word" characters, so this will leave those and spaces. In my tests, this correctly removes punctuation from English, Japanese and German sentences while leaving the surrounding characters. But dollars to doughnuts there will be edge cases that trip up just about any solution — dealing with the huge variety of languages in the world (some of which don't even have words as we know them) is an incredibly complex task.
The good way to do this would be to use the new(ish) unicode character classes in regex, such as \P{L} to match anything that is not a letter (in any language) according to unicode. Unfortunately, it seems that Ruby doesn't support this, even in 1.9.
Perhaps the 1.9 regex parser is smart enough to not match the bytes that make up special symbols in unicode characters, so simple enumerating all the characters to strip can work, though. That assumes you really can enumerate all characters you wish to filter out, which might be a lot more than the symbols in ASCII, like logical not, aeroplane, etc...
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I know that this is a little vague, so for context, think of it as "a character you could tweet," or something like that. My question is how many valid unicode characters are there that a browser or a service that supports utf8 could resolve, in such a way that a utf8 browser could copy and paste it around without any issues.
I guess what I don't want is the full character space, because I know a lot of it is reserved for command characters or reserved characters that wouldn't be shown (unless I'm super wrong!).
UTF-8 isn't the important factor, since all of the standard Unicode encodings (UTF-8, UTF-16, UTF-32) encode the same character space, just in different ways.
From your explanation I see you don't just want the 1,112,064 valid Unicode code points?
Unicode 6.0 and ISO/IEC 10646:2010 define 109,449 characters, but a handful of those are what you're calling "control characters". Which ones do or don't fall into that category depends on how you're counting. Copying and pasting may result in some characters being treated as identical to one another, or ignore altogether, depending on the OS and the programs doing the copying and pasting.
However because Unicode is forward compatible, some systems will correctly preserve characters which haven't yet been assigned. After all, just because you're running Windows XP and you copy and paste a document with characters that weren't standardised until 2009 doesn't mean you expect them to vanish. There could be a million or so extra possible characters by this way of thinking, although their visual appearance may be indistinguishable in some places.
Right single quotation mark (U+2019)
vs.
Apostrophe (U+0027)
What is the difference between these two characters?
I ran into this issue where I use CAtlString to load a string from a resource file, and on some Windows installations, the LoadString fails when trying to load a string that contains U+2019, but it works on some other Windows installations. The U+2019 character appears in strings in my resource file that I copied from Word, and U+0027 appears in stirngs that I hand coded. Why does LoadString (sometimes) choke on this?
What is the difference between these two characters?
Arguable!
Going by the names, one would imagine that the curly ‹’› is only for use as a quotation mark, and that the straight ‹'› is only for use as a real apostrophe, an indicator of omitted letters.
However traditional typesetting practice in English is always to use a curly ‹’› to render an apostrophe. Personally—and I may be alone here—I don't like this. It can make for more ambiguous reading:
“He said, ‘It’s fish ’n’ chips’...”
with the apostrophes being straight it's (marginally) clearer where the quotation ends:
“He said, ‘It's fish 'n' chips’...”
and the apostrophe being ‘straight’ makes more sense to me because its purpose of indicating omitted letters has no inherent directionality, whereas quotation marks are clearly asymmetrical in purpose.
In traditional ASCII, of course, there are no smart quotes, so the apostrophe is always used for both...
on some Windows installations, the LoadString fails when trying to load a string that contains U+2019, but it works on some other Windows installations.
Here you are meeting the horror of the ‘ANSI’ code page. This is a default character encoding that is different across different Windows install locales. So on a machine in the Western region, you get different results when you read a resource to when you read it on a Japanese Windows.
It is highly unfortunate that Windows has varying default code pages instead of using a single global encoding like UTF-8, but it's too late to fix now. If you compile your whole application as a Unicode app (so you'll be using LoadStringW rather than LoadStringA) then you can cope with non-ASCII characters like the smart quotes much better.
If you can't move to a Unicode application you're a bit stuck. You won't be able to handle non-ASCII characters like the smart quotes globally, so stick with ASCII characters like the straight apostrophe ‹'› alone.
The U+2019 character appears in strings in my resource file that I copied from Word
Yes, Word has an annoying AutoCorrect feature that replaces all apostrophes you type with smart quotes. This is especially undesirable when you are dealing with code, where ‹’› will break the program; but it's also wrong even for plain old English, as it's not possible to correctly guess the desired direction of the quote. (It'll get one of the apostrophes in “fish 'n' chips” the wrong way round, for example.)
I suggest turning off the automatic-replace-with-smart-quotes feature. If you want the smart quotes, it's better to type them deliberately. Unfortunately they are inconvenient to type on most keyboard layouts, often requiring obscure Alt+numpad sequences. Personally I use this one to drop them onto Alt+[] keys.
Historically, single-quote and double-quote come in pairs, left (open) and right (close).
For many years the character sets of computers were limited, having a single form of each.
Now, with the advent of Unicode, the full forms are available, but support for them is still limited. Programming languages still use the simple forms, and the full forms can still cause problems.
(Using Ruby 1.8)
I only have a brief understanding of encoding and such...but what I want to know is, in any given script handling any given text-file, is there some universal library or call I need to make to turn non-standard characters into their nearest printable equivalent. I realize there's no "all-in-one" fix, but this is for a English (U.S. gov't) text file, and so I'm wondering if there's something that mitigates what must be a relatively common issue in English text formatting.
For example, in a text file, I have an entry like this:
0-823
That hyphen is just literally a hyphen as I've typed it out. In the file though, it's something that looks like a hyphen (an n-dash?) but when copy and pasting it...for example, into this browser text box, it doesn't show up.
Printing it out via a Ruby script gets this:
08�23
How do I get my script to resolve it into a dash. Or something other than a gremlin?
It's very common to run into hyphen-like characters and dashes, especially in the output of word-processors. Converting them isn't too hard if you know what the byte is that represents the character, but gets to be a pain when you get a document with several different ones. It gets worse as you throw other accented characters into the mix.
Ruby 1.8 doesn't support multibyte and Unicode character sets as well as 1.9+, but you can work around that somewhat by using the Iconv library.
Iconv lets you convert between various character-sets, such as US-ASCII, ISO-8859-1 and WIN-1252. It's smarter than a regex, because it knows how to convert from accented characters, to similarly looking characters, or ignore them if nothing similar exists, allowing your transliteration to degrade gracefully.
I have some example code in an answer to a related question. Also read James Grey's article linked in the answer. It explains the problem and ways to fix it, ending up with recommending Iconv too.
You could whitelist with gsub:
string.gsub(/[^a-zA-Z0-9]/)
Without knowing more information, I can't build the perfect regex for you, but the general idea is to replace anything that's not what you're expecting (anything not a letter or number or expected symbols).
I am working on an application that allows users to input Japanese language characters. I am trying to come up with a way to determine whether the user's input is a Japanese kana (hiragana, katakana, or kanji).
There are certain fields in the application where entering Latin text would be inappropriate and I need a way to limit certain fields to kanji-only, or katakana-only, etc.
The project uses UTF-8 encoding. I don't expect to accept JIS or Shift-JIS input.
Ideas?
It sounds like you basically need to just check whether each Unicode character is within a particular range. The Unicode code charts should be a good starting point.
If you're using .NET, my MiscUtil library has some Unicode range support - it's primitive, but it should do the job. I don't have the source to hand right now, but will update this post with an example later if it would be helpful.
Not sure of a perfect answer, but there is a Unicode range for katakana and hiragana listed on Wikipedia. (Which I would expect are also available from unicode.org as well.)
Hiragana: Unicode: 3040-309F
Katakana: Unicode: 30A0–30FF
Checking those ranges against the input should work as a validation for hiragana or katakana for Unicode in a language-agnostic manner.
For kanji, I would expect it to be a little more complicated, as I
expect that the Chinese characters used in Chinese and Japanese are both included in the same range, but then again, I may be wrong here. (I can't expect that Simplified Chinese and Traditional Chinese to be included in the same range...)
oh oh! I had this one once... I had a regex with the hiragana, then katakana and then the kanji. I forget the exact codes, I'll go have a look.
regex is great because you double the problems. And I did it in PHP, my choice for extra strong auto problem generation
--edit--
$pattern = '/[^\wぁ-ゔァ-ヺー\x{4E00}-\x{9FAF}_\-]+/u';
I found this here, but it's not great... I'll keep looking
--edit--
I looked through my portable hard drive.... I thought I had kept that particular snippet from the last company... sorry.
What is your opinion on whether a tagging user interface widget should require commas or spaces as the delimiter? For example, this site uses spaces, requiring multi-word tags to use a hyphen. I assumed this was some design suggestion from Joel; but then I realized that Facebook and Wordpress use commas.
So what should it be? Or does it not matter much? Let's suppose the users of this widget are generally computer literate but not terribly so.
I would try to think about the domain of the tags and figure out what is the likelihood that potential tags would contain spaces.
For example, most things on this site are single word or acronyms, so it's not difficult to use spaces.
On the other hand, when tagging facebook photos, for example, an average tag is something like "spring break", "frat party", "random hookup", "secretary of state", etc. So dealing with space interpretation or with quotes is more difficult, hence commas make more sense.
I'm not familiar with a specific rule.
If you're thinking of tag clouds though, spaces make less sense.
Be fault-tolerant, if possible. For example, would it work to use whatever is provided? The following two inputs could result in the same, if parsed nicely:
foo bar "hello world"
foo, bar, hello world
Both would result in three obvious tags.
I realize that this would it make hard to parse the following input unambiguously:
hello world
In that case, I'd probably read two distinct tags.
commas. it is more natural. you can use words that include spaces more easily. other solutions seem to complicated for human beings (maybe not for programmers but they think different - remember the "u" in gui stands for "user")
i would go for a comma as it is more natural to separate multiple word tags by commas then use hyphens or other less usable replacement techniques
I don't think it matters. I think for a programming site, most of your tags will not be multi-word so it makes to use a space delimiter. But I think you could make a very compelling argument either way and it really just comes down to personal choice.