This script is compling without errors in play.golang.org: http://play.golang.org/p/Hlr-IAc_1f
But when I run in on my machine, much longer than I expect happens with nothing happening in the terminal.
What I am trying to build is a PartOfSpeech Tagger.
I think the longest part is loading lexicon.txt into a map and then comparing each word with every word there to see if it has already been tagged in the lexicon. The lexicon only contains verbs. But doesn't every word need to be checked to see if it is a verb.
The larger problem is that I don't know how to determine if a word is a verb with an easy heuristic like adverbs, adjectives, etc.
(Quoting):
I don't know how to determine if a word is a verb with an easy heuristic like adverbs, adjectives, etc.
I can't speak to any issues in your Go implementation, but I'll address the larger problem of POS tagging in general. It sounds like you're attempting to build a rule-based unigram tagger. To elaborate a bit on those terms:
"unigram" means you're considering each word in the sentence separately. Note that a unigram tagger is inherently limited, in that it cannot disambiguate words which can take on multiple POS tags. E.g., should you tag 'fish' as a noun or a verb? Is 'last' a verb or an adverb?
"rule-based" means exactly what it sounds like: a set of rules to determine the tag for each word. Rule-based tagging is limited in a different way - it requires considerable development effort to assemble a ruleset that will handle a reasonable portion of the ambiguity in common language. This effort might be appropriate if you're working in a language for which we don't have good training resources, but in most common languages, we now have enough tagged text to train high-accuracy tagging models.
State-of-the-art for POS tagging is above 97% accuracy on well-formed newswire text (accuracy on less formal genres is naturally lower). A rule-based tagger will probably perform considerably worse (you'll have to determine the accuracy level needed to meet your requirements). If you want to continue down the rule-based path, I'd recommend reading this tutorial. The code is based on Haskell, but it will help you learn the concepts and issues in rule-based tagging.
That said, I'd strongly recommend you look at other tagging methods. I mentioned the weaknesses of unigram tagging. Related approaches would be 'bigram', meaning that we consider the previous word when tagging word n, 'trigram' (usually the previous 2 words, or the previous word, the current word, and the following word); more generally, 'n-gram' refers to considering a sequence of n words (often, a sliding window around the word we're currently tagging). That context can help us disambiguate 'fish', 'last', 'flies', etc.
E.g., in
We fish
we probably want to tag fish as a verb, whereas in
ate fish
it's certainly a noun.
The NLTK tutorial might be a good reference here. An solid n-gram tagger should get you above 90% accuracy; likely above 95% (again on newswire text).
More sophisticated methods (known as 'structured inference') consider the entire tag sequence as a whole. That is, instead of trying to predict the most probable tag for each word separately, they attempt to predict the most probable sequence of tags for the entire input sequence. Structured inference is of course more difficult to implement and train, but will usually improve accuracy vs. n-gram approaches. If you want to read up on this area, I suggest Sutton and McCallum's excellent introduction.
You've got a large array argument in this function:
func stringInArray(a string, list [214]string) bool{
for _, b := range list{
if b == a{
return true;
}
}
return false
}
The array of stopwords gets copied each time you call this function.
Mostly in Go, you should uses slices rather than arrays most of the time. Change the definition of this to be list []string and define stopWords as a slice rather than an array:
stopWords := []string{
"and", "or", ...
}
Probably an even better approach would be to build a map of the stopWords:
isStopWord := map[string]bool{}
for _, sw := range stopWords {
isStopWord[sw] = true
}
and then you can check if a word is a stopword quickly:
if isStopWord[word] { ... }
Related
I have some text generated by some lousy OCR software.
The output contains mixture of words and space-separated characters, which should have been grouped into words. For example,
Expr e s s i o n Syntax
S u m m a r y o f T e r minology
should have been
Expression Syntax
Summary of Terminology
What algorithms can group characters into words?
If I program in Python, C#, Java, C or C++, what libraries provide the implementation of the algorithms?
Thanks.
Minimal approach:
In your input, remove the space before any single letter words. Mark the final words created as part of this somehow (prefix them with a symbol not in the input, for example).
Get a dictionary of English words, sorted longest to shortest.
For each marked word in your input, find the longest match and break that off as a word. Repeat on the characters left over in the original "word" until there's nothing left over. (In the case where there's no match just leave it alone.)
More sophisticated, overkill approach:
The problem of splitting words without spaces is a real-world problem in languages commonly written without spaces, such as Chinese and Japanese. I'm familiar with Japanese so I'll mainly speak with reference to that.
Typical approaches use a dictionary and a sequence model. The model is trained to learn transition properties between labels - part of speech tagging, combined with the dictionary, is used to figure out the relative likelihood of different potential places to split words. Then the most likely sequence of splits for a whole sentence is solved for using (for example) the Viterbi algorithm.
Creating a system like this is almost certainly overkill if you're just cleaning OCR data, but if you're interested it may be worth looking into.
A sample case where the more sophisticated approach will work and the simple one won't:
input: Playforthefunofit
simple output: Play forth efunofit (forth is longer than for)
sophistiated output: Play for the fun of it (forth efunofit is a low-frequency - that is, unnatural - transition, while for the is not)
You can work around the issue with the simple approach to some extent by adding common short-word sequences to your dictionary as units. For example, add forthe as a dictionary word, and split it in a post processing step.
Hope that helps - good luck!
I am trying to tag a HTML page full of space-separated numbers like "5320412185 5320412184 5320412189..." to observe how the tagger behaves with numbers. I'm using english-left3words-distsim.tagger in the constructor. I'm observing on the console that most of the numbers are tagged as CD but at times there are also numbers getting tagged as NN. I searched on the FAQ page of nlp.stanford.edu but I couldn't find this there. Can anyone help me in understanding this?
I don't know if I should need to mention this: I'm feeding each number separately to the tagger by splitting the huge input(1045000 numbers!) based on space-delimiter.
From Part-of-Speech Tagging Guidelines for the Penn Treebank Project (3rd Revision)
Sometimes, it is unclear whether one is cardinal number or a noun. In general, it should be tagged as a
cardinal number (CD) even when its sense is not clearly that of a numeral.
EXAMPLE: one/CD of the best reasons
But if it could be pluralized or modified by an adjective in a particular context, it is a common noun (NN).
EXAMPLE: the only (good) one/NN of its kind
(cf. the only (good) ones/NNS of their kind)
In the collocation another one, one should also be tagged as a common noun (NN).
Hyphenated fractions one-half, three-fourths, seven-eighths, one-and-a-half, seven-and-three-eighths should
be tagged as adjectives (JJ) when they are prenominal modifiers, but as adverbs (RB) if they could be
replaced by double or twice.
For further reading: http://repository.upenn.edu/cgi/viewcontent.cgi?article=1603&context=cis_reports
I have a large set of Words and Phrases (a lexicon or dictionary) which includes wildcards. I need to find all instances of those Words and Phrases within a much smaller String (~150 characters at the moment).
Initially, I wanted to run the operation in reverse; that is to check to see if each word in my smaller string exists within the Lexicon, which could be implemented as a Hash Table. The problem is that some of these values in my Lexicon are not single words and many are wildcards (e.g. substri*).
I'm thinking of using the Rabin-Karp algorithm but I'm not sure this is the best choice.
What's an efficient algorithm or method to perform this operation?
Sample Data:
The dictionary contains hundreds of words and can potentially expand. These words may end with wildcard characters (asterisks). Here are some random examples:
good
bad
freed*
careless*
great loss
The text we are analyzing (at this point) are short, informal (grammar-wise) English statements. The prime example of text (again, at this point in time) would be a Twitter Tweet. These are limited to roughly 140 Characters. For example:
Just got the Google nexus without a contract. Hands down its the best phone
I've ever had and the only thing that could've followed my N900.
While it may be helpful to note that we are performing very simple Sentiment Analysis on this text; our Sentiment Analysis technique is not my concern. I'm simply migrating an existing solution to a "real-time" processing system and need to perform some optimizations.
I think this is an excellent use case for the Aho-Corasick string-matching algorithm, which is specifically designed to find all matches of a large set of strings in a single string. It runs in two phases - a first phase in which a matching automaton is created (which can be done in advance and requires only linear time), and a second phase in which the automaton is used to find all matches (which requires only linear time, plus time proportional to the total number of matches). The algorithm can also be adapted to support wildcard searching as well.
Hope this helps!
One answer I wanted to throw out there was the Boyer-Moore search algorithm. It is the algorithm that grep uses. Grep is probably one of the fastest search tools available. In addition, you could use something like GNU Parallel to have grep run in parallel, thus really speeding up the algorithm.
In addition, here is a good article that you might find interesting.
You might still use your original idea, of checking every word in the text against the dictionary. However, in order to run it efficently you need to index the dictionary, to make lookups really fast. A trick used in information retrival systems is to store a so called permuterm index (http://nlp.stanford.edu/IR-book/html/htmledition/permuterm-indexes-1.html).
Basically what you want to do is to store in a dictionary every possible permutation of the words (e.g. for house):
house$
ouse$h
use$ho
...
e$hous
This index can then be used to quickly check against wildcard queries. If for example you have ho*e you can look in the permuterm index for a term beginning with e$ho and you would quickly find a match with house.
The search itself is usually done with some logarithmic search strategy (binary search or b-trees) and thus is usally very fast.
So long as the patterns are for complete words: you don't want or to match storage; spaces and punctuation are match anchors, then a simple way to go is translate your lexicon into a scanner generator input (for example you could use flex), generate a scanner, and then run it over your input.
Scanner generators are designed to identify occurrences of tokens in input, where each token type is described by a regular expression. Flex and similar programs create scanners rapidly. Flex handles up to 8k rules (in your case lexicon entries) by default, and this can be expanded. The generated scanners run in linear time and in practice are very fast.
Internally, the token regular expressions are transformed in a standard "Kleene's theorem" pipeline: First to a NFA, then to a DFA. The DFA is then transformed to its unique minimum form. This is encoded in a HLL table, which is emitted inside a wrapper that implements the scanner by referring to the table. This is what flex does, but other strategies are possible. For example the DFA can be translated to goto code where the DFA state is represented implicitly by the instruction pointer as the code runs.
The reason for the spaces-as-anchors caveat is that scanners created by programs like Flex are normally incapable of identifying overlapping matches: strangers could not match both strangers and range, for example.
Here is a flex scanner that matches the example lexicon you gave:
%option noyywrap
%%
"good" { return 1; }
"bad" { return 2; }
"freed"[[:alpha:]]* { return 3; }
"careless"[[:alpha:]]* { return 4; }
"great"[[:space:]]+"loss" { return 5; }
. { /* match anything else except newline */ }
"\n" { /* match newline */ }
<<EOF>> { return -1; }
%%
int main(int argc, char *argv[])
{
yyin = argc > 1 ? fopen(argv[1], "r") : stdin;
for (;;) {
int found = yylex();
if (found < 0) return 0;
printf("matched pattern %d with '%s'\n", found, yytext);
}
}
And to run it:
$ flex -i foo.l
$ gcc lex.yy.c
$ ./a.out
Good men can only lose freedom to bad
matched pattern 1 with 'Good'
matched pattern 3 with 'freedom'
matched pattern 2 with 'bad'
through carelessness or apathy.
matched pattern 4 with 'carelessness'
This doesn't answer the algorithm question exactly, but check out the re2 library. There are good interfaces in Python, Ruby and assorted other programming languages. In my experience, it's blindly fast, and removed quite similar bottlenecks in my code with little fuss and virtually no extra code on my part.
The only complexity comes with overlapping patterns. If you want the patterns to start at word boundaries, you should be able partition the dictionary into a set of regular expressions r_1, r_2, ..., r_k of the form \b(foobar|baz baz\S*|...) where each group in r_{i+1} has a prefix in r_i. You can then short circuit evaluations since if r_{i+1} matches then r_i must have matched.
Unless you're implementing your algorithm in highly-optimized C, I'd bet that this approach will be faster than any of the (algorithmically superior) answers elsewhere in this thread.
Let me get this straight. You have a large set of queries and one small string and you want to find instances of all those queries in that string.
In that case I suggest you index that small document like crazy so that your search time is as short as possible. Hell. With that document size I would even consider doing small mutations (to match wildcards and so on) and would index them as well.
I had a very similar task.
Here's how I solved it, the performance is unbelievable
http://www.foibg.com/ijita/vol17/ijita17-2-p03.pdf
One-line summary: suggest optimal (lookup-speed/compactness) data structure(s) for a multi-lingual dictionary representing primarily Indo-European languages (list at bottom).
Say you want to build some data structure(s) to implement a multi-language dictionary for let's say the top-N (N~40) European languages on the internet, ranking choice of language by number of webpages (rough list of languages given at bottom of this question).
The aim is to store the working vocabulary of each language (i.e. 25,000 words for English etc.) Proper nouns excluded. Not sure whether we store plurals, verb conjugations, prefixes etc., or add language-specific rules on how these are formed from noun singulars or verb stems.
Also your choice on how we encode and handle accents, diphthongs and language-specific special characters e.g. maybe where possible we transliterate things (e.g. Romanize German ß as 'ss', then add a rule to convert it). Obviously if you choose to use 40-100 characters and a trie, there are way too many branches and most of them are empty.
Task definition: Whatever data structure(s) you use, you must do both of the following:
The main operation in lookup is to quickly get an indication 'Yes this is a valid word in languages A,B and F but not C,D or E'. So, if N=40 languages, your structure quickly returns 40 Booleans.
The secondary operation is to return some pointer/object for that word (and all its variants) for each language (or null if it was invalid). This pointer/object could be user-defined e.g. the Part-of-Speech and dictionary definition/thesaurus similes/list of translations into the other languages/... It could be language-specific or language-independent e.g. a shared definition of pizza)
And the main metric for efficiency is a tradeoff of a) compactness (across all N languages) and b) lookup speed. Insertion time not important. The compactness constraint excludes memory-wasteful approaches like "keep a separate hash for each word" or "keep a separate for each language, and each word within that language".
So:
What are the possible data structures, how do they rank on the
lookup speed/compactness curve?
Do you have a unified structure for all N languages, or partition e.g. the Germanic languages into one sub-structure, Slavic into
another etc? or just N separate structures (which would allow you to
Huffman-encode )?
What representation do you use for characters, accents and language-specific special characters?
Ideally, give link to algorithm or code, esp. Python or else C. -
(I checked SO and there have been related questions but not this exact question. Certainly not looking for a SQL database. One 2000 paper which might be useful: "Estimation of English and non-English Language Use on the WWW" - Grefenstette & Nioche. And one list of multi-language dictionaries)
Resources: two online multi-language dictionaries are Interglot (en/ge/nl/fr/sp/se) and LookWayUp (en<->fr/ge/sp/nl/pt).
Languages to include:
Probably mainly Indo-European languages for simplicity: English, French, Spanish, German, Italian, Swedish + Albanian, Czech, Danish, Dutch, Estonian, Finnish, Hungarian, Icelandic, Latvian, Lithuanian, Norwegian, Polish, Portuguese, Romanian, Russian, Serbo Croat, Slovak, Slovenian + Breton, Catalan, Corsican, Esperanto, Gaelic, Welsh
Probably include Russian, Slavic, Turkish, exclude Arabic, Hebrew, Iranian, Indian etc. Maybe include Malay family too. Tell me what's achievable.
I will not win points here, but some things.
A multi-language dictionary is a large and time-consuming undertaking. You did not talk in detail about the exact uses for which your dictionary is intended: statistical probably, not translating, not grammatical, .... Different usages require different data to be collected, for instance classifying "went" as passed tense.
First formulate your first requirements in a document, and with a programmed interface prototype. Asking data structures before algorithmic conception I see often for complex business logic. One would then start out wrong, risking feature creep. Or premature optimisation, like that romanisation, which might have no advantage, and bar bidrectiveness.
Maybe you can start with some active projects like Reta Vortaro; its XML might not be efficient, but give you some ideas for organisation. There are several academic linguistic projects. The most relevant aspect might be stemming: recognising greet/greets/greeted/greeter/greeting/greetings (#smci) as belonging to the same (major) entry. You want to take the already programmed stemmers; they often are well-tested and already applied in electronic dictionaries. My advise would be to research those projects without losing to much energy, impetus, to them; just enough to collect ideas and see where they might be used.
The data structures one can think up, are IMHO of secondary importance. I would first collect all in a well defined database, and then generate the software used data structures. You can then compare and measure alternatives. And it might be for a developer the most interesting part, creating a beautiful data structure & algorithm.
An answer
Requirement:
Map of word to list of [language, definition reference].
List of definitions.
Several words can have the same definition, hence the need for a definition reference.
The definition could consist of a language bound definition (grammatical properties, declinations), and/or a language indepedendant definition (description of the notion).
One word can have several definitions (book = (noun) reading material, = (verb) reserve use of location).
Remarks
As single words are handled, this does not consider that an occuring text is in general mono-lingual. As a text can be of mixed languages, and I see no special overhead in the O-complexity, that seems irrelevant.
So a over-general abstract data structure would be:
Map<String /*Word*/, List<DefinitionEntry>> wordDefinitions;
Map<String /*Language/Locale/""*/, List<Definition>> definitions;
class Definition {
String content;
}
class DefinitionEntry {
String language;
Ref<Definition> definition;
}
The concrete data structure:
The wordDefinitions are best served with an optimised hash map.
Please let me add:
I did come up with a concrete data structure at last. I started with the following.
Guava's MultiMap is, what we have here, but Trove's collections with primitive types is what one needs, if using a compact binary representation in core.
One would do something like:
import gnu.trove.map.*;
/**
* Map of word to DefinitionEntry.
* Key: word.
* Value: offset in byte array wordDefinitionEntries,
* 0 serves as null, which implies a dummy byte (data version?)
* in the byte arrary at [0].
*/
TObjectIntMap<String> wordDefinitions = TObjectIntHashMap<String>();
byte[] wordDefinitionEntries = new byte[...]; // Actually read from file.
void walkEntries(String word) {
int value = wordDefinitions.get(word);
if (value == 0)
return;
DataInputStream in = new DataInputStream(
new ByteArrayInputStream(wordDefinitionEntries));
in.skipBytes(value);
int entriesCount = in.readShort();
for (int entryno = 0; entryno < entriesCount; ++entryno) {
int language = in.readByte();
walkDefinition(in, language); // Index to readUTF8 or gzipped bytes.
}
}
I'm not sure whether or not this will work for your particular problem, but here's one idea to think about.
A data structure that's often used for fast, compact representations of language is a minimum-state DFA for the language. You could construct this by creating a trie for the language (which is itself an automaton for recognizing strings in the language), then using of the canonical algorithms for constructing a minimum-state DFA for the language. This may require an enormous amount of preprocessing time, but once you've constructed the automaton you'll have extremely fast lookup of words. You would just start at the start state and follow the labeled transitions for each of the letters. Each state could encode (perhaps) a 40-bit value encoding for each language whether or not the state corresponds to a word in that language.
Because different languages use different alphabets, it might a good idea to separate out each language by alphabet so that you can minimize the size of the transition table for the automaton. After all, if you have words using the Latin and Cyrillic alphabets, the state transitions for states representing Greek words would probably all be to the dead state on Latin letters, while the transitions for Greek characters for Latin words would also be to the dead state. Having multiple automata for each of these alphabets thus could eliminate a huge amount of wasted space.
A common solution to this in the field of NLP is finite automata. See http://www.stanford.edu/~laurik/fsmbook/home.html.
Easy.
Construct a minimal, perfect hash function for your data (union of all dictionaries, construct the hash offline), and enjoy O(1) lookup for the rest of eternity.
Takes advantage of the fact your keys are known statically. Doesn't care about your accents and so on (normalize them prior to hashing if you want).
I had a similar (but not exactly) task: implement a four-way mapping for sets, e.g. A, B, C, D
Each item x has it's projections in all of the sets, x.A, x.B, x.C, x.D;
The task was: for each item encountered, determine which set it belongs to and find its projections in other sets.
Using languages analogy: for any word, identify its language and find all translations to other languages.
However: in my case a word can be uniquely identified as belonging to one language only, so no false friends such as burro in Spanish is donkey in English, whereas burro in Italian is butter in English (see also https://www.daytranslations.com/blog/different-meanings/)
I implemented the following solution:
Four maps/dictionaries matching the entry to its unique id (integer)
AtoI[x.A] = BtoI[x.B] = CtoI[x.C] = DtoI[x.D] = i
Four maps/dictionaries matching the unique id to the corresponding language
ItoA[i] = x.A;
ItoB[i] = x.B;
ItoC[i] = x.C;
ItoD[i] = x.D;
For each encounter x, I need to do 4 searches at worst to get its id (each search is O(log(N))); then 3 access operations, each O(log(N)). All in all, O(log(N)).
I have not implemented this, but I don't see why hash sets cannot be used for either set of dictionaries to make it O(1).
Going back to your problem:
Given N concepts in M languages (so N*M words in total)
My approach adapts in the following way:
M lookup hashsets, that give you integer id for every language (or None/null if the word does not exist in the language).
Overlapped case is covered by the fact that lookups for different languages will yield different ids.
For each word, you do M*O(1) lookups in the hash sets corresponding to languages, yielding K<=M ids, identifying the word as belonging to K languages;
for each id you need to do (M-1)*O(1) lookups in actual dictionaries, mapping K ids to M-1 translations each)
In total, O(MKM) which I think is not bad, given your M=40 and K will be much smaller than M in most cases (K=1 for quite a lot of words).
As for storage: NM words + NM integers for the id-to-word dictionaries, and the same amount for reverse lookups (word-to-id);
I am working on a project that requires the parsing of log files. I am looking for a fast algorithm that would take groups messages like this:
The temperature at P1 is 35F.
The temperature at P1 is 40F.
The temperature at P3 is 35F.
Logger stopped.
Logger started.
The temperature at P1 is 40F.
and puts out something in the form of a printf():
"The temperature at P%d is %dF.", Int1, Int2"
{(1,35), (1, 40), (3, 35), (1,40)}
The algorithm needs to be generic enough to recognize almost any data load in message groups.
I tried searching for this kind of technology, but I don't even know the correct terms to search for.
I think you might be overlooking and missed fscanf() and sscanf(). Which are the opposite of fprintf() and sprintf().
Overview:
A naïve!! algorithm keeps track of the frequency of words in a per-column manner, where one can assume that each line can be separated into columns with a delimiter.
Example input:
The dog jumped over the moon
The cat jumped over the moon
The moon jumped over the moon
The car jumped over the moon
Frequencies:
Column 1: {The: 4}
Column 2: {car: 1, cat: 1, dog: 1, moon: 1}
Column 3: {jumped: 4}
Column 4: {over: 4}
Column 5: {the: 4}
Column 6: {moon: 4}
We could partition these frequency lists further by grouping based on the total number of fields, but in this simple and convenient example, we are only working with a fixed number of fields (6).
The next step is to iterate through lines which generated these frequency lists, so let's take the first example.
The: meets some hand-wavy criteria and the algorithm decides it must be static.
dog: doesn't appear to be static based on the rest of the frequency list, and thus it must be dynamic as opposed to static text. We loop through a few pre-defined regular expressions and come up with /[a-z]+/i.
over: same deal as #1; it's static, so leave as is.
the: same deal as #1; it's static, so leave as is.
moon: same deal as #1; it's static, so leave as is.
Thus, just from going over the first line we can put together the following regular expression:
/The ([a-z]+?) jumps over the moon/
Considerations:
Obviously one can choose to scan part or the whole document for the first pass, as long as one is confident the frequency lists will be a sufficient sampling of the entire data.
False positives may creep into the results, and it will be up to the filtering algorithm (hand-waving) to provide the best threshold between static and dynamic fields, or some human post-processing.
The overall idea is probably a good one, but the actual implementation will definitely weigh in on the speed and efficiency of this algorithm.
Thanks for all the great suggestions.
Chris, is right. I am looking for a generic solution for normalizing any kind of text. The solution of the problem boils down to dynmamically finding patterns in two or more similar strings.
Almost like predicting the next element in a set, based on the previous two:
1: Everest is 30000 feet high
2: K2 is 28000 feet high
=> What is the pattern?
=> Answer:
[name] is [number] feet high
Now the text file can have millions of lines and thousands of patterns. I would like to parse the files very, very fast, find the patterns and collect the data sets that are associated with each pattern.
I thought about creating some high level semantic hashes to represent the patterns in the message strings.
I would use a tokenizer and give each of the tokens types a specific "weight".
Then I would group the hashes and rate their similarity. Once the grouping is done I would collect the data sets.
I was hoping, that I didn't have to reinvent the wheel and could reuse something that is already out there.
Klaus
It depends on what you are trying to do, if your goal is to quickly generate sprintf() input, this works. If you are trying to parse data, maybe regular expressions would do too..
You're not going to find a tool that can simply take arbitrary input, guess what data you want from it, and produce the output you want. That sounds like strong AI to me.
Producing something like this, even just to recognize numbers, gets really hairy. For example is "123.456" one number or two? How about this "123,456"? Is "35F" a decimal number and an 'F' or is it the hex value 0x35F? You're going to have to build something that will parse in the way you need. You can do this with regular expressions, or you can do it with sscanf, or you can do it some other way, but you're going to have to write something custom.
However, with basic regular expressions, you can do this yourself. It won't be magic, but it's not that much work. Something like this will parse the lines you're interested in and consolidate them (Perl):
my #vals = ();
while (defined(my $line = <>))
{
if ($line =~ /The temperature at P(\d*) is (\d*)F./)
{
push(#vals, "($1,$2)");
}
}
print "The temperature at P%d is %dF. {";
for (my $i = 0; $i < #vals; $i++)
{
print $vals[$i];
if ($i < #vals - 1)
{
print ",";
}
}
print "}\n";
The output from this isL
The temperature at P%d is %dF. {(1,35),(1,40),(3,35),(1,40)}
You could do something similar for each type of line you need to parse. You could even read these regular expressions from a file, instead of custom coding each one.
I don't know of any specific tool to do that. What I did when I had a similar problem to solve was trying to guess regular expressions to match lines.
I then processed the files and displayed only the unmatched lines. If a line is unmatched, it means that the pattern is wrong and should be tweaked or another pattern should be added.
After around an hour of work, I succeeded in finding the ~20 patterns to match 10000+ lines.
In your case, you can first "guess" that one pattern is "The temperature at P[1-3] is [0-9]{2}F.". If you reprocess the file removing any matched line, it leaves "only":
Logger stopped.
Logger started.
Which you can then match with "Logger (.+).".
You can then refine the patterns and find new ones to match your whole log.
#John: I think that the question relates to an algorithm that actually recognises patterns in log files and automatically "guesses" appropriate format strings and data for it. The *scanf family can't do that on its own, it can only be of help once the patterns have been recognised in the first place.
#Derek Park: Well, even a strong AI couldn't be sure it had the right answer.
Perhaps some compression-like mechanism could be used:
Find large, frequent substrings
Find large, frequent substring patterns. (i.e. [pattern:1] [junk] [pattern:2])
Another item to consider might be to group lines by edit-distance. Grouping similar lines should split the problem into one-pattern-per-group chunks.
Actually, if you manage to write this, let the whole world know, I think a lot of us would like this tool!
#Anders
Well, even a strong AI couldn't be sure it had the right answer.
I was thinking that sufficiently strong AI could usually figure out the right answer from the context. e.g. Strong AI could recognize that "35F" in this context is a temperature and not a hex number. There are definitely cases where even strong AI would be unable to answer. Those are the same cases where a human would be unable to answer, though (assuming very strong AI).
Of course, it doesn't really matter, since we don't have strong AI. :)
http://www.logparser.com forwards to an IIS forum which seems fairly active. This is the official site for Gabriele Giuseppini's "Log Parser Toolkit". While I have never actually used this tool, I did pick up a cheap copy of the book from Amazon Marketplace - today a copy is as low as $16. Nothing beats a dead-tree-interface for just flipping through pages.
Glancing at this forum, I had not previously heard about the "New GUI tool for MS Log Parser, Log Parser Lizard" at http://www.lizardl.com/.
The key issue of course is the complexity of your GRAMMAR. To use any kind of log-parser as the term is commonly used, you need to know exactly what you're scanning for, you can write a BNF for it. Many years ago I took a course based on Aho-and-Ullman's "Dragon Book", and the thoroughly understood LALR technology can give you optimal speed, provided of course that you have that CFG.
On the other hand it does seem you're possibly reaching for something AI-like, which is a different order of complexity entirely.