| --- Log opened Sun Nov 25 00:00:52 2007 |
| 00:01 | <@ToxicFrog> | Yeah. Regexes are what you need here. |
| 00:02 | <@ToxicFrog> | 'Effect [0-9]+ Starting Offset Y := ([0-9]+)' |
| 00:05 | <@Reiver> | Brackets for doing what, out of interest? |
| 00:05 | <@ToxicFrog> | Captures. |
| 00:05 | <@Reiver> | Captures? |
| 00:05 | <@ToxicFrog> | Sections of the regex you're particularly interested in, and want to manipulate seperately. |
| 00:05 | <@ToxicFrog> | Using Lua here, but I believe python does it similarly, if I did something like: |
| 00:05 | <@Reiver> | ...So I run the regex, and it automatically splits out the final number? |
| 00:06 | <@ToxicFrog> | foo = "the number is 64" |
| 00:06 | <@Vornicus> | Square brackets are for "choose a character" |
| 00:06 | <@ToxicFrog> | foo:match("number is [0-9]+") => "number is 64" |
| 00:06 | <@ToxicFrog> | foo:match("number is ([0-9]+)") => "64" |
| 00:07 | <@Vornicus> | Parentheses are for "this is a pile of things that go together, and I'll capture and give you the result of that section of regex." |
| 00:07 | <@Vornicus> | Curly braces are for "the previous thing should show up a certain number of times" |
| 00:07 | <@ToxicFrog> | So typically, you have a regex that matches the entire line/block/etc, and then you enclose individual pieces in (), so you get them seperately |
| 00:07 | <@ToxicFrog> | And then you do something with them. |
| 00:08 | <@Vornicus> | Note that parentheses aren't /just/ for captures |
| 00:08 | <@ToxicFrog> | Not everything supports grouping, though. |
| 00:08 | <@ToxicFrog> | Whereas everything I'm aware of does support captures. |
| 00:09 | <@ToxicFrog> | But, yes. In some regex implementations, you can write, say, (abc)? to mean 'either abc or nothing' |
| 00:10 | <@ToxicFrog> | Or (abc)+ to mean 'one or more repetitions of abc' |
| 00:17 | | GeekSoldier is now known as GeekSoldier|bed |
| 00:18 | <@Reiver> | Aha. |
| 00:18 | <@Reiver> | Hmn. |
| 00:18 | <@Reiver> | So if I have regexed like that, I then want to... hmn |
| 00:19 | <@Reiver> | How would I take that captured number, modify it, then bolt it /back onto/ the line? |
| 00:19 | <@ToxicFrog> | Some languages have functions that do that in one step; lua has string.gsub, and since lua's string library is largely yoinked from python, python probably has an equivalent |
| 00:20 | <@ToxicFrog> | You can also just put the string back together by hand: |
| 00:20 | <@ToxicFrog> | x,y = buffer:match("The coordinates are ([0-9]+),([0-9]+)") |
| 00:20 | <@ToxicFrog> | x = x*2; y = y/2 |
| 00:21 | <@ToxicFrog> | printf("The coordinates are %d,%d", x, y) |
| 00:24 | <@Vornicus> | re.sub |
| 00:25 | | You're now known as TheWatcher[T-2] |
| 00:26 | <@Vornicus> | YOu can even specify a function that takes the match and figures out the replacement. |
| 00:28 | <@ToxicFrog> | Sounds identical to gsub. |
| 00:29 | <@Vornicus> | Yep. |
| 00:30 | <@Vornicus> | You pass 1 as the fourth parameter to get sub. |
| 00:31 | <@ToxicFrog> | ? |
| 00:31 | <@ToxicFrog> | Oh. "replace the first match" |
| 00:31 | <@ToxicFrog> | (string.sub in lua is "extract substring") |
| 00:32 | <@Vornicus> | heh |
| 00:32 | <@Vornicus> | Some langauges (perl?) have sub and gsub separate but doing s/// and s///g |
| 00:33 | <@ToxicFrog> | Yeah. |
| 00:33 | <@ToxicFrog> | Lua gsub is actually something of an everything box - it can do an arbitrary number of replacements, and the replacement is either a string with backrefs, a lookup table of strings with backrefs, or a function |
| 00:47 | | You're now known as TheWatcher[zZzZ] |
| 01:20 | <@Reiver> | if line.startswith('Starting Position Offset ' + axis): |
| 01:20 | <@Reiver> | print>>target, line.split(':=')[0], ':= ', (float((line.split(':='))[1]) + offset) |
| 01:20 | <@Reiver> | becomes |
| 01:21 | <@Reiver> | ...wait no that doesn't work |
| 01:21 | | * Reiver goes back to poke again. |
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| 01:32 | <@McMartin> | You might want to check to ensure that len(line.split(':=')) is in fact two. |
| 01:34 | <@Reiver> | McM: Actually, I was halfway through trying to convert my splits to regexes. |
| 01:34 | <@Reiver> | Which look to be infinitely more useful, if I can get the things to work~ |
| 01:34 | <@Vornicus> | line.split(':=',1) |
| 01:35 | <@McMartin> | Vorn: Doesn't catch lines with no := at all |
| 01:35 | <@Vornicus> | true |
| 01:36 | <@ToxicFrog> | Personally, I'd just try to match against 'Effect ([0-9]+) Starting Offset Y := ([0-9]+)' |
| 01:36 | <@ToxicFrog> | Replace the whitespace with ' +' or whatever as appropriate |
| 01:36 | <@ToxicFrog> | Then change the coordinate value and re-create the line with % |
| 01:36 | <@ToxicFrog> | Stuff that doesn't match, you skip |
| 01:37 | <@Reiver> | I'm mostly tripping up on syntax. |
| 01:37 | <@ToxicFrog> | That, I'm afraid I can't help you with. |
| 01:38 | <@Reiver> | Fair enough~ |
| 01:38 | | * Reiver dives into helpfiles to work out how one makes a regex work in general. |
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| 01:41 | <@ToxicFrog> | Oh. Regex syntax I can do. |
| 01:41 | <@ToxicFrog> | I thought you meant python syntax. |
| 01:41 | <@Reiver> | Nooo, I mean getting teh python syntax to read the regex syntax. |
| 01:41 | <@ToxicFrog> | (although I don't know any peculiarities specific to python's regex impl) |
| 01:42 | <@McMartin> | If you're running into backslash problems, use raw strings |
| 01:43 | <@McMartin> | Either """strings 4tw""" or r"strings 4tw" |
| 01:43 | <@Vornicus> | r'this is a raw string' |
| 01:43 | <@McMartin> | However, the latter cannot end with an odd number of backslashes. |
| 01:45 | <@Reiver> | ...Oh, no no, much more basic than that. |
| 01:45 | <@Vornicus> | Show me what you've got |
| 01:45 | <@Vornicus> | I'll tell you how to fix it. |
| 01:46 | <@Vornicus> | TF and I are good at regex. |
| 01:47 | <@Reiver> | if line.match('Effect [0-9]+ Starting Offset Y := (Y)+'): |
| 01:48 | <@Reiver> | Yeah, I know I'm botching it~ |
| 01:53 | <@ToxicFrog> | Ok. First of all, recall that [0-9]+ is "one or more digits" |
| 01:53 | <@ToxicFrog> | So you use that where you're looking for an integer. |
| 01:54 | <@Reiver> | ok |
| 01:54 | <@ToxicFrog> | "Y", in contrast, matches the literal character 'Y' |
| 01:54 | <@Reiver> | Er, yeah, I was planning to ask about that, as the Y is a placeholder. |
| 01:54 | <@Reiver> | How does one insert variables into a regex? |
| 01:54 | <@ToxicFrog> | And () should completely enclose the pattern you want to match; move the + inside the () |
| 01:55 | <@ToxicFrog> | ...same way you insert variables into any string. |
| 01:55 | <@ToxicFrog> | Regexes in python aren't a special type, they're just strings. |
| 01:55 | <@ToxicFrog> | So something like, say: |
| 01:55 | <@ToxicFrog> | 'Effect [0-9]+ Starting Offset Y := (%d)' % y_value |
| 01:56 | <@Reiver> | ...Clearly I need to learn more about Python strings. |
| 01:57 | <@ToxicFrog> | We discussed this earlier, I thought? |
| 01:57 | <@ToxicFrog> | Yes, we did |
| 01:58 | <@ToxicFrog> | 3h15m ago - printf and the string-% operator |
| 02:01 | <@Reiver> | ...Oh, is that what Vorn was talking about~ |
| 02:01 | | * Reiver thought that was a formatting thingy. Which, well, it is but he misread it as specifically a 'line things up' formatting thingy. |
| 02:05 | <@Reiver> | Actually, that's wrong anyhow. |
| 02:05 | <@Reiver> | What I need is a [0-9]+ that allows decimals. |
| 02:06 | <@ToxicFrog> | [.0-9]+ |
| 02:06 | <@Reiver> | ...That was easier than expected |
| 02:06 | <@Reiver> | Is there a specific order to such things? |
| 02:06 | <@ToxicFrog> | Although that will also match, say, "123...456" |
| 02:07 | <@ToxicFrog> | So you might try instead: [0-9]*\.?[0-9]+ |
| 02:07 | <@ToxicFrog> | (you need the \escape because '.' has a specific meaning in regexes - "any one character") |
| 02:07 | <@Reiver> | Hrm |
| 02:07 | <@ToxicFrog> | No. Ordering is unimportant. |
| 02:07 | <@Reiver> | Well, I'm not worried about the special case being an issue. |
| 02:07 | <@ToxicFrog> | Well, apart from - |
| 02:07 | <@Reiver> | If that was in the file, it would cause a loading error~ |
| 02:08 | <@ToxicFrog> | [0-9] and [9-0] aren't equivalent, but [1234] and [4321] are. |
| 02:08 | <@ToxicFrog> | (at least, I don't think they're equivalent...) |
| 02:08 | <@Reiver> | [9-0] would be doing...? |
| 02:08 | <@Vornicus> | 9-0 doesn't work |
| 02:09 | <@Vornicus> | 0-9 is "everything with an ascii value between ord('0') and ord('9'), inclusive" |
| 02:09 | <@Vornicus> | 9-0 is backwards |
| 02:09 | <@ToxicFrog> | There's probably a perl option somewhere that interprets 9-0 as "everything except 12345678"~ |
| 02:09 | <@Vornicus> | heh |
| 02:31 | <@Reiver> | Hey, uh, Vorn? |
| 02:31 | <@Reiver> | What syntax should I be using to try and get match to work? |
| 02:31 | <@Vornicus> | "work"? |
| 02:31 | <@Reiver> | line.match isn't the correct one. I'm pretty sure I Should be using re.match, but then I don't quite know where to insert line, and uh |
| 02:32 | <@Vornicus> | re.match(pattern, line) |
| 02:32 | <@Vornicus> | and usually you want search |
| 02:34 | <@Reiver> | Match is more strict, though? |
| 02:35 | <@Vornicus> | Match will only match at the beginning of the line; however I prefer starting my regex with ^ instead of using match, because it's more obvious. |
| 02:36 | <@Reiver> | ? |
| 02:36 | <@Vornicus> | ^ at the beginning of a regex means "this is the start of a line" |
| 02:37 | <@Vornicus> | $ at the end of a regex means "this is the end of a line" |
| 02:37 | <@Reiver> | aha |
| 02:37 | <@Reiver> | so |
| 02:38 | <@Reiver> | Now to figure out how to use the regex to edit a line once I've found the data inside it. |
| 02:38 | | * Reiver goes to reread the backscroll~ |
| 02:40 | <@Reiver> | So ([0-9]+) lets you return the number specified. Are you able to then edit that number without any fancy commands? |
| 02:41 | <@ToxicFrog> | Well, once it's returned it's just a variable. |
| 02:41 | <@ToxicFrog> | If you mean "can you mutate it inside the string", see re.sub, discussed above |
| 02:41 | <@ToxicFrog> | Or putting the string back together with the % operator, also discussed above |
| 02:43 | <@Reiver> | I'm mostly looking at the putting the string back together one. |
| 02:44 | <@Reiver> | Once "if re.match('Effect [0-9]+ Starting Offset Y := ([.0-9]+)', line):" has found the line and returned me the variable, I then want to add/subtract to it, then recreate the entire line as it was. |
| 02:45 | <@Reiver> | Previously, I was doing this with .split, because I'd already split the string into two in order to modify the number. |
| 02:45 | <@ToxicFrog> | Well, for that, you'll need the effect # as well |
| 02:45 | <@ToxicFrog> | So you need to wrap that in (), too |
| 02:45 | <@Reiver> | Aaah |
| 02:45 | <@Reiver> | I was wondering how to get the regex'd line back out again. Answer is: Don't bother, just recreate it? |
| 02:47 | <@ToxicFrog> | Yes. Hence "putting it back together by hand" |
| 02:47 | <@ToxicFrog> | For more complicated stuff - for example, stuff with lots of variable segments where it's tedious to capture them all - you use re.sub |
| 02:49 | <@Vornicus> | note that re.sub you must match /only/ that which you wish to replace. |
| 02:50 | <@ToxicFrog> | Yes. But you can pass that to a function, which can do more involved stuff to it. |
| 02:51 | <@Reiver> | Aha. So putting back together by hand it is then~ |
| 02:51 | | * Reiver was just wonderin' if there wasn't a more, I dunno, 'elegant' way, so to speak. |
| 03:52 | <@Vornicus> | Note that you can create a pattern that knows what to look for before it. |
| 03:52 | <@Vornicus> | But it's limited - lookbehind must have a fixed length, though I'm not sure why. |
| 03:57 | <@ToxicFrog> | There's probably a formal proof somewhere that is, as it is said, as twisted and impenetrable as a granite octopus. |
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| 12:10 | <@Reiver> | ho-kay, I sleep now. I shall make sense of dis in da mornink |
| 12:11 | < GeekSoldier> | heh. sleep well, and don't let visions of wayward regexes haunt your dreams. |
| 12:11 | <@Vornicus> | Sleep is your friend. |
| 12:12 | <@Reiver> | Mostly I am getting mixed up in "Okay, I have my regex there with the parentheses around it, but... wait a minute actually what I really need is this written out /again/ the next line down, hrm, is that right I have no id-- bugger it, SLEP" |
| 12:13 | | Reiver is now known as ReivZzz |
| 12:14 | <@Vornicus> | Heh. Been there, done that. |
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| 17:02 | | * ToxicFrog goes to track down Chris Roberts |
| 17:03 | <@ToxicFrog> | Hmm. Now chairman of Ascendant Pictures, can't be contacted directly. |
| 17:03 | | * ToxicFrog grabs Claw Marks and rummages through it for other programmers |
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| 18:03 | | * ToxicFrog proves that fuzzy min intersection and fuzzy max union obey DeMorgan's Laws |
| 18:41 | <@ToxicFrog> | <3 unicode |
| 18:41 | <@ToxicFrog> | Actually, let's try that again |
| 18:41 | <@ToxicFrog> | ? unicode |
| 18:45 | | * AnnoDomini gets a box. |
| 18:45 | <@AnnoDomini> | But that's probably since I use Fixedsys. |
| 18:45 | < GeekSoldier> | ? |
| 18:46 | <@ToxicFrog> | I use LucidaTypewriter, which has so far contained all the unicode symbols I've tried to use. |
| 18:46 | <@ToxicFrog> | Yes, GS, 0x2665 UNICODE BLACK HEART SUIT |
| 18:48 | < GeekSoldier> | I got: a-circumflex, trademark, yen |
| 18:49 | < GeekSoldier> | perhaps I should finally put unicode on here. |
| 18:49 | <@ToxicFrog> | You're probably using Latin-1 rather than UTF8, then. |
| 18:49 | < GeekSoldier> | yeah. |
| 18:53 | < GeekSoldier> | I don't think IceChat does unicode. |
| 18:55 | < GeekSoldier> | oh, it does. |
| 18:58 | < GeekSoldier> | or not. |
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| 19:17 | | * AnnoDomini changes to Courier New, on a whim, at the same time changing some colour settings. |
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| --- Log closed Mon Nov 26 00:00:58 2007 |