ISBN numbers come with random dash positions
978-618-81543-7-7
9786-18-81-5437-7
97-86-18-81-5437-7
How could i get them every time without knowing dash positions?
Just delete every - with your language of choice.
With Ruby :
"978-618-81543-7-7".delete('-')
#=> "9786188154377"
If you really want to use a regex :
"978-618-81543-7-7".gsub(/-/,'')
If you have multiple lines with isbns :
isbns = "978-618-81543-7-7
9786-18-81-5437-7
97-86-18-81-5437-7"
p isbns.scan(/\b[-\d]+\b/).map{|number_and_dash| number_and_dash.delete('-')}
#=> ["9786188154377", "9786188154377", "9786188154377"]
Pretty easy use of regex, google it to learn more. In Python:
import re
nums=re.findall('\d+',isbnstring)
This will give a list of the numbers. To join them to a string:
isbn=''.join(nums)
As per comments below, if you're working a file you could work it line by line:
with open(isbnfile) as desc:
for isbnstring in desc:
#Do the above and more.
As one example. There are a ton of ways to do this. I just realized from the command line sed is a good choice as well:
sed 's/-//g' isbnfile > newisbnfile
I'm using PIG to generate a list of URLs that have been recently visited. In each of the URLs, there is a string of numbers that represents the product page visited. I'm trying to use a regex_extract_all() function to extract just the string of numbers, which vary in length from 6-8. The string of digits can be found directly after jobs2/view/ and usually ends with +&cd but sometimes they may end with ).
Here are a few example URLs:
(http://a.com/search?q=cache:QD7vZRHkPQoJ:ca.xyz.com/jobs2/view/17069404+&cd=1&hl=en&ct=clnk&gl=ca)
(http://a.com/search?q=cache:G9323j2oNbAJ:ca.xyz.com/jobs2/view/5977065+&cd=1&hl=en&ct=clnk&gl=ca)
(http://a.com/search?q=cache:aNspmG11qAJ:hk.xyz.com/jobs2/view/16988928+&cd=2&hl=zh-TW&ct=clnk&gl=hk)
(http://a.com/search?q=cache:aNspmG11AJ:hk.xyz.com/jobs2/view/16988928+&cd=2&hl=zh-TW&ct=clnk&gl=hk)
(http://a.com/search?q=cache:aNspmG11qAJ:hk.xyz.com/jobs2/view/16988928+&cd=2&hl=zh-TW&ct=cl k&gl=hk)
Here is the current regex I am using:
J = FOREACH jpage GENERATE FLATTEN(REGEX_EXTRACT_ALL(TEXTCOLUMN, '\/view\/(\d+)\+\&')) as (output:chararray)
I have also tried other forms such as:
'[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]', 'view.([0-9]+)', 'view\/([\d]+)\+',
'[0-9][0-9][0-9]+', and
'[0-9][0-9][0-9]*'; none of which work.
Can anybody assist here or have another way of going about it?
Much appreciated,
MM
Reason for"Unexpected character 'D'" is, you need to put double backslash instead of single backslash. eg just replace [\d+] to [\\d+]
Here your solution, please validate all your inputs strings
input.txt
http://a.com/search?q=cache:QD7vZRHkPQoJ:ca.xyz.com/jobs2/view/17069404+&cd=1&hl=en&ct=clnk&gl=ca
http://a.com/search?q=cache:G9323j2oNbAJ:ca.xyz.com/jobs2/view/5977065+&cd=1&hl=en&ct=clnk&gl=ca
http://a.com/search?q=cache:aNspmG11qAJ:hk.xyz.com/jobs2/view/16988928+&cd=2&hl=zh-TW&ct=clnk&gl=hk
http://a.com/search?q=cache:aNspmG11AJ:hk.xyz.com/jobs2/view/16988928+&cd=2&hl=zh-TW&ct=clnk&gl=hk
http://a.com/search?q=cache:aNspmG11qAJ:hk.xyz.com/jobs2/view/16988928+&cd=2&hl=zh-TW&ct=clk&gl=hk
http://a.com/search?q=cache:aNspmG11qAJ:hk.xyz.com/jobs2/view/16988928)=2&hl=zh-TW&ct=clk&gl=hk
http://webcache.googleusercontent.com/search?q=cache:http://my.linkedin.com/jobs2/view/9919248
Updated Pigscript:
A = LOAD 'input.txt' as line;
B = FOREACH A GENERATE REGEX_EXTRACT(line,'.*/view/(\\d+)([+|&|cd|)?]+)?',1);
dump B;
(17069404)
(5977065)
(16988928)
(16988928)
(16988928)
(16988928)
I'm not familiar with PIG, but this regex will match your target:
(?<=/jobs2/view/)\d+
By using a (non-consuming) look behind, the entire match (not just a group of the match) is your number.
Let's say there might be indexed documents involving phrases like "Facebook acquires WhatsApp for $19 B". I want to search for "Facebook[\s\w+]*Whatsapp" and expect all the phrases that contain Facebook and WhatsApp separated by a word (acquires, buys etc).
How to do it in lucene? Is it efficient enough to work for thousands of such queries in a 50GB corpus?
p.s. So far I've experimented with regex search using RegexpQuery and I'm unable to work for a multi-word phrase. Here's a line from the code:
Term term = new Term("text", "Facebook[\\s\\w+]*Whatsapp");
Term t = new Term(userQuery);
Query query = new RegexpQuery(term);
You could use query "Facebook Whatsapp"~1, so all documents will be matched where distance between this words will be less or equal to 1
For more information - http://wiki.apache.org/lucene-java/LuceneFAQ#Is_there_a_way_to_use_a_proximity_operator_.28like_near_or_within.29_with_Lucene.3F and http://searchhub.org//2009/07/18/the-spanquery/
UPD.
And also make sure your "text" field is a TextField so it is
tokenized.
– Jeff French
At one point in my app, I need to match some strings against a pattern. Let's say that some of the sample strings look as follows:
Hi there, John.
What a lovely day today!
Lovely sunset today, John, isn't it?
Will you be meeting Linda today, John?
Most (not all) of these strings are from pre-defined patterns as follows:
"Hi there, %s."
"What a lovely day today!"
"Lovely sunset today, %s, isn't it?"
"Will you be meeting %s today, %s?"
This library of patterns is ever-expanding (currently at around 1,500), but is manually maintained. The input strings though (the first group) is largely unpredictable. Though most of them will match one of the patterns, some of them will not.
So, here's my question: Given a string (from the first group) as input, I need to know which of the patterns (known second group) it matched. If nothing matched, it needs to tell me that.
I'm guessing the solution involves building a regex out of the patterns, and iteratively checking which one matched. However, I'm unsure what the code to build those regexes looks like.
Note: The strings I've given here are for illustration purposes. In reality, the strings aren't human generated, but are computer-generated human-friendly strings as shown above from systems I don't control. Since they aren't manually typed in, we don't need to worry about things like typos and other human errors. Just need to find which pattern it matches.
Note 2: I could modify the patterns library to be some other format, if that makes it easier to construct the regexes. The current structure, with the printf style %s, isn't set in stone.
I am looking at this as a parsing problem. The idea is that the parser function takes a string and determines if it is valid or not.
The string is valid if you can find it among the given patterns. That means you need an index of all the patterns. The index must be a full text index. Also it must match according to the word position. eg. it should short circuit if the first word of the input is not found among the first word of the patterns. It should take care of the any match ie %s in the pattern.
One solution is to put the patterns in an in memory database (eg. redis) and do a full text index on it. (this will not match according to word position) but you should be able to narrow down to the correct pattern by splitting the input into words and searching. The searches will be very fast because you have a small in memory database. Also note that you are looking for the closest match. One or more words will not match. The highest number of matches is the pattern you want.
An even better solution is to generate your own index in a dictionary format. Here is an example index for the four patterns you gave as a JavaScript object.
{
"Hi": { "there": {"%s": null}},
"What: {"a": {"lovely": {"day": {"today": null}}}},
"Lovely": {"sunset": {"today": {"%s": {"isnt": {"it": null}}}}},
"Will": {"you": {"be": {"meeting": {"%s": {"today": {"%s": null}}}}}}
}
This index is recursive descending according to the word postion. So search for the first word, if found search for the next within the object returned by the first and so on. Same words at a given level will have only one key. You should also match the any case. This should be blinding fast in memory.
My first thought would be to have the regexp engine take all the trouble of handling this. They're usually optimised to handle large amounts of text so it shouldn't be that much of a performance hassle. It's brute force but the performance seems to be okay. And you could split the input into pieces and have multiple processes handle them. Here's my moderately tested solution (in Python).
import random
import string
import re
def create_random_sentence():
nwords = random.randint(4, 10)
sentence = []
for i in range(nwords):
sentence.append("".join(random.choice(string.lowercase) for x in range(random.randint(3,10))))
ret = " ".join(sentence)
print ret
return ret
patterns = [ r"Hi there, [a-zA-Z]+.",
r"What a lovely day today!",
r"Lovely sunset today, [a-zA-Z]+, isn't it?",
r"Will you be meeting [a-zA-Z]+ today, [a-zA-Z]+\?"]
for i in range(95):
patterns.append(create_random_sentence())
monster_pattern = "|".join("(%s)"%x for x in patterns)
print monster_pattern
print "--------------"
monster_regexp = re.compile(monster_pattern)
inputs = ["Hi there, John.",
"What a lovely day today!",
"Lovely sunset today, John, isn't it?",
"Will you be meeting Linda today, John?",
"Goobledigoock"]*2000
for i in inputs:
ret = monster_regexp.search(i)
if ret:
print ".",
else:
print "x",
I've created a hundred patterns. This is the maximum limit of the python regexp library. 4 of them are your actual examples and the rest are random sentences just to stress performance a little.
Then I combined them into a single regexp with 100 groups. (group1)|(group2)|(group3)|.... I'm guessing you'll have to sanitise the inputs for things that can have meanings in regular expressions (like ? etc.). That's the monster_regexp.
Testing one string against this tests it against 100 patterns in a single shot. There are methods that fetch out the exact group which was matched. I test 10000 strings 80% of which should match and 10% which will not. It short cirtcuits so if there's a success, it will be comparatively quick. Failures will have to run through the whole regexp so it will be slower. You can order things based on the frequency of input to get some more performance out of it.
I ran this on my machine and this is my timing.
python /tmp/scratch.py 0.13s user 0.00s system 97% cpu 0.136 total
which is not too bad.
However, to run a pattern against such a large regexp and fail will take longer so I changed the inputs to have lots of randomly generated strings that won't match and then tried. 10000 strings none of which match the monster_regexp and I got this.
python /tmp/scratch.py 3.76s user 0.01s system 99% cpu 3.779 total
Similar to Noufal's solution, but returns the matched pattern or None.
import re
patterns = [
"Hi there, %s.",
"What a lovely day today!",
"Lovely sunset today, %s, isn't it",
"Will you be meeting %s today, %s?"
]
def make_re_pattern(pattern):
# characters like . ? etc. have special meaning in regular expressions.
# Escape the string to avoid interpretting them as differently.
# The re.escape function escapes even %, so replacing that with XXX to avoid that.
p = re.escape(pattern.replace("%s", "XXX"))
return p.replace("XXX", "\w+")
# Join all the pattens into a single regular expression.
# Each pattern is enclosed in () to remember the match.
# This will help us to find the matched pattern.
rx = re.compile("|".join("(" + make_re_pattern(p) + ")" for p in patterns))
def match(s):
"""Given an input strings, returns the matched pattern or None."""
m = rx.match(s)
if m:
# Find the index of the matching group.
index = (i for i, group in enumerate(m.groups()) if group is not None).next()
return patterns[index]
# Testing with couple of patterns
print match("Hi there, John.")
print match("Will you be meeting Linda today, John?")
Python solution. JS should be similar.
>>> re2.compile('^ABC(.*)E$').search('ABCDE') == None
False
>>> re2.compile('^ABC(.*)E$').search('ABCDDDDDDE') == None
False
>>> re2.compile('^ABC(.*)E$').search('ABX') == None
True
>>>
The trick is to use ^ and $ to bound your pattern and making it a "template". Use (.*) or (.+) or whatever it is that you want to "search" for.
The main bottleneck for you, imho, will be iterating through a list of these patterns. Regex searches are computationally expensive.
If you want a "does any pattern match" result, build a massive OR based regex and let your regex engine handle the 'OR'ing for you.
Also, if you have only prefix patterns, check out the TRIE data structure.
This could be a job for sscanf, there is an implementation in js: http://phpjs.org/functions/sscanf/; the function being copied is this: http://php.net/manual/en/function.sscanf.php.
You should be able to use it without changing the prepared strings much, but I have doubts about the performances.
the problem isn't clear to me. Do you want to take the patterns and build regexes out of it?
Most regex engines have a "quoted string" option. (\Q \E). So you could take the string and make it
^\QHi there,\E(?:.*)\Q.\E$
these will be regexes that match exactly the string you want outside your variables.
if you want to use a single regex to match just a single pattern, you can put them in grouped patterns to find out which one matched, but that will not give you EVERY match, just the first one.
if you use a proper parser (I've used PEG.js), it might be more maintainable though. So that's another option if you think you might get stuck in regex hell
I had this question a couple of times before, and I still couldn't find a good answer..
In my current problem, I have a console program output (string) that looks like this:
Number of assemblies processed = 1200
Number of assemblies uninstalled = 1197
Number of failures = 3
Now I want to extract those numbers and to check if there were failures. (That's a gacutil.exe output, btw.) In other words, I want to match any number [0-9]+ in the string that is preceded by 'failures = '.
How would I do that? I want to get the number only. Of course I can match the whole thing like /failures = [0-9]+/ .. and then trim the first characters with length("failures = ") or something like that. The point is, I don't want to do that, it's a lame workaround.
Because it's odd; if my pattern-to-match-but-not-into-output ("failures = ") comes after the thing i want to extract ([0-9]+), there is a way to do it:
pattern(?=expression)
To show the absurdity of this, if the whole file was processed backwards, I could use:
[0-9]+(?= = seruliaf)
... so, is there no forward-way? :T
pattern(?=expression) is a regex positive lookahead and what you are looking for is a regex positive lookbehind that goes like this (?<=expression)pattern but this feature is not supported by all flavors of regex. It depends which language you are using.
more infos at regular-expressions.info for comparison of Lookaround feature scroll down 2/3 on this page.
If your console output does actually look like that throughout, try splitting the string on "=" when the word "failure" is found, then get the last element (or the 2nd element). You did not say what your language is, but any decent language with string splitting capability would do the job. For example
gacutil.exe.... | ruby -F"=" -ane "print $F[-1] if /failure/"