extract text data using regexp in MATLAB - regex

I'm dealing with extracting visibility data in METAR(airport weather observation data).
Visibility is a 4 digit(0~9) data, and can also be expressed as'CAVOK' when visibility is good.
but it's quite tricky to use regexp. (METAR data have many variations.)
Data sample(MET_VIS) below:
201903072300 METAR RKPC 072300Z 17003KT 110V210 CAVOK 05/02 Q1026 NOSIG=
201903062000 METAR RKPC 062000Z 33018G29KT 4000 BR FEW012 SCT025 08/04 Q1018 WS R13 R31 NOSIG=
201903062200 METAR RKPC 062200Z 33015KT 290V350 9999 SCT030 07/03 Q1019 NOSIG=
201903080000 METAR RKPC 080000Z 29002KT CAVOK 08/02 Q1027 NOSIG=
I want to extract CAVOK, 4000, 9999, CAVOK on each line.
I tried but this code doesn't work with line 3 :( It returns blank.
regexp(MET_VIS(i),'((?<=KT\s)\d{4})|CAVOK','match')

The third value does not end on KT. What you might do is use another positive lookbehind to check if the string before it ends on KT and match a range of matching 7 times A-Z0-9 followed by a whitespace char after it.
Then you either match 4 digits or CAVOK using an alternation (?:\d{4}|CAVOK) or else you could match CAVOK anywhere in the string.
Add a word boundary after it to prevent the match being part of a larger word.
(?:(?<=KT\s)|(?<=KT [A-Z0-9]{7}\s))(?:\d{4}|CAVOK)\b
Regex demo

You could also make an assumption about the range of "words" from the end your target should be allowed to occur in. For example:
/\b(?:\d{4}|CAVOK)\b(?=(?: \S+){3,9}$)/gm
See regex demo.
Here we're looking for a four-digit number or the phrase CAVOK only, if it is followed by 3 to 9 non-space substrings of variable length until the end of the line.

Related

How Can I Create a RegEx Pattern that will Get N Words Using Custom Word Boundary?

I need a RegEx pattern that will return the first N words using a custom word boundary that is the normal RegEx white space (\s) plus punctuation like .,;:!?-*_
EDIT #1: Thanks for all your comments.
To be clear:
I'd like to set the characters that would be the word delimiters
Lets call this the "Delimiter Set", or strDelimiters
strDelimiters = ".,;:!?-*_"
nNumWordsToFind = 5
A word is defined as any contiguous text that does NOT contain any character in strDelimiters
The RegEx word boundary is any contiguous text that contains one or more of the characters in strDelimiters
I'd like to build the RegEx pattern to get/return the first nNumWordsToFind using the strDelimiters.
EDIT #2: Sat, Aug 8, 2015 at 12:49 AM US CT
#maraca definitely answered my question as originally stated.
But what I actually need is to return the number of words ≤ nNumWordsToFind.
So if the source text has only 3 words, but my RegEx asks for 4 words, I need it to return the 3 words. The answer provided by maraca fails if nNumWordsToFind > number of actual words in the source text.
For example:
one,two;three-four_five.six:seven eight nine! ten
It would see this as 10 words.
If I want the first 5 words, it would return:
one,two;three-four_five.
I have this pattern using the normal \s whitespace, which works, but NOT exactly what I need:
([\w]+\s+){<NumWordsOut>}
where <NumWordsOut> is the number of words to return.
I have also found this word boundary pattern, but I don't know how to use it:
a "real word boundary" that detects the edge between an ASCII letter
and a non-letter.
(?i)(?<=^|[^a-z])(?=[a-z])|(?<=[a-z])(?=$|[^a-z])
However, I would want my words to allow numbers as well.
IAC, I have not been able how to use the above custom word boundary pattern to return the first N words of my text.
BTW, I will be using this in a Keyboard Maestro macro.
Can anyone help?
TIA.
All you have to do is to adapt your pattern ([\w]+\s+){<NumWordsOut>} to, including some special cases:
^[\s.,;:!?*_-]*([^\s.,;:!?*_-]+([\s.,;:!?*_-]+|$)){<NumWordsOut>}
1. 2. 3. 4. 5.
Match any amount of delimiters before the first word
Match a word (= at least one non-delimiter)
The word has to be followed by at least one delimiter
Or it can be at the end of the string (in case no delimiter follows at the end)
Repeat 2. to 4. <NumWordsOut> times
Note how I changed the order of the -, it has to be at the start or end, otherwise it needs to be escaped: \-.
Thanks to #maraca for providing the complete answer to my question.
I just wanted to post the Keyboard Maestro macro that I have built using #maraca's RegEx pattern for anyone interested in the complete solution.
See KM Forum Macro: Get a Max of N Words in String Using RegEx

Regular Expressions in R

I found somewhat similar questions
R - Select string text between two values, regex for n characters or at least m characters,
but I'm still having trouble
say I have a string in r
testing_String <- "AK ADAK NAS PADK ADK 70454 51 53N 176 39W 4 X T 7"
And I need to be able to pull anything between the first element in the string that contains 2 characters (AK) and PADK,ADK. PADK and ADK will change in character but will always be 4 and 3 characters in length respectively.
So I would need to pull
ADAK NAS
I came up with this but its picking up everything from AK to ADK
^[A-Za-z0_9_]{2}(.*?) +[A-Za-z0_9_]{4}|[A-Za-z0_9_]{3,}
If I understood your question correctly, this should do the trick:
\b[A-Z]{2}\s+(.+?)\s+[A-Z]{4}\s+[A-Z]{3}\b
Demo
You'll have to switch the perl = TRUE option (to use a decent regex engine).
\b means word boundary. So this pattern looks for a match starting with a 2-letter word and ending with a 4 letter word followed by a 3 letter word. Your value will be in the first group.
Alternatively, you can write the following to avoid using the capturing group:
\b[A-Z]{2}\s+\K.+?(?=\s+[A-Z]{4}\s+[A-Z]{3}\b)
But I'd prefer the first method because it's easier to read.
Lookbehind is supported for perl=TRUE, so this regex will do what you want:
(?<=\w{2}\s).*?(?=\s+[^\s]{4}\s[^\s]{2})

best approach for my pattern match

So, I've built a regex which follows this:
4!a2!a2!c[3!c]
which is translated to
4 alpha character followed by
2 alpha characters followed by
2 characters followed by
3 optional character
this is a standard format for SWIFT BIC code HSBCGB2LXXX
my regex to pull this out of string is:
(?<=:32[^:]:)(([a-zA-Z]{4}[a-zA-Z]{2})[0-9][a-zA-Z]{1}[X]{3})
Now this is targeting a specific tag (32) and works, however, I'm not sure if it's the cleanest, plus if there are any characters before H then it fails.
the string being matched against is:
:32B:HsBfGB4LXXXHELLO
the following returns HSBCGB4LXXX, but this:
:32B:2HsBfGB4LXXXHELLO
returns nothing.
EDIT
For clarity. I have a string which contains multiple lines all starting with :2xnumber:optional letter (eg, :58A:) i want to specify a line to start matching in and return a BIC from anywhere in the line.
EDIT
Some more example data to help:
:20:ABCDERF Z
:23B:CRED
:32A:140310AUD2120,
:33B:AUD2120,
:50K:/111222333
Mr Bank of Dad
Dads house
England
:52D:/DBEL02010987654321
address 1
address 2
:53B:/HSBCGB2LXXX
:57A://AU124040
AREFERENCE
:59:/44556677
A line which HSBCGB2LXXX contains a BIC
:70:Another line of data
:71A:Even more
Ok, so I need to pass in as a variable the tag 53 or 59 and return the BIC HSBCGB2LXXX only!
Your regex can be simplified, and corrected to allow a character before the H, to:
:32[^:]:.?([a-zA-Z]{6}\d[a-zA-Z]XXX)
The changes made were:
Lost the look behind - just make it part of the match
Inserting .? meaning "optional character"
([a-zA-Z]{4}[a-zA-Z]{2}) ==> [a-zA-Z]{6} (4+2=6)
[0-9] ==> \d (\d means "any digit")
[X]{3} ==> XXX (just easier to read and less characters)
Group 1 of the match contains your target
I'm not quite sure if I understand your question completely, as your regular expression does not completely match what you have described above it. For example, you mentioned 3 optional characters, but in the regexp you use 3 mandatory X-es.
However, the actual regular expression can be further cleaned:
instead of [a-zA-Z]{4}[a-zA-Z]{2}, you can simply use [a-zA-Z]{6}, and the grouping parentheses around this might be unnecessary;
the {1} can be left out without any change in the result;
the X does not need surrounding brackets.
All in all
(?<=:32[^:]:)([a-zA-Z]{6}[0-9][a-zA-Z]X{3})
is shorter and matches in the very same cases.
If you give a better description of the domain, probably further improvements are also possible.

Need to capture single character, but ignore digit

I'm parsing out flight info.
Here's the sample data:
E0.777 7 3:09
E0.319 N 1:43
E0.735 8 1:45
E0.735 N 1:48
E0.M80 9 3:21
E0.733 1:48
I need to populate fields like this:
Equipment: 735
On Time: N
Duration: 1:48
Problem I'm having is capturing the Y or N character but ignoring the single digit, then capturing the duration.
This is the expression I have tried:
#"^.{3}(.{3})\s?([N|Y]?)?(?:[0-9]\s+)?(\w{4})"
Edit: I updated the sample data to clarify my question. Equipment is not always three digits, it could be a character and two digits. The data between the equipment and the duration could be a boolean N or Y, a single digit, or white space. Only the boolean should be captured.
Firstly, you mix up the concepts of alternation and character classes [Y|N] would match 3 different characters: Y or | or N. Either use (...) or leave out the pipe.
Secondly your double ? after the character class does not really do anything. Thirdly, at the end you only match consecutive spaces if a digit was found. But if there is no digit, the last ? will ignore the subpattern, thus not allowing spaces either.
Lastly, \w does not match :.
Try this:
#"^.{3}(\d{3})\s?(?:([NY])|\d)\s+(\d:\d\d)"
You should also think about restricting the repeated . at the beginning to a more precise character class (i.e \w{2}\., but I don't know the possibilities there).
#"^..\.(\d{3})\s(?:([YN])|\d)\s*(\S{4})"
Changed .{3} to ..\. which is a bit more specific about there being a literal . for character 3.
(?:([YN])|\d) matches either Y/N or a digit, but only captures a Y or N. Notice that it's [YN] not [Y|N].
Changed \w{4} to \S{4} since \w doesn't match colons :.
This will do it...
^\w\d\.(\d{3})\s(?:([YN])|\d)\s*(\d:\d{2})$
I made some other changes to your regex because it was easier for me to just rewrite it based off your data then to try to modify what you had.
This will capture the Y or N or it won't capture anything in that group. I also tried to be more specific with your duration regex.
Update: This works with your new requirements...
^\w\d\.(\w{3})\s(?:([YN])|\d|\s)\s*(\d:\d{2})$
You can see it working on your data here... http://regexr.com?32j1b
(hover over each line to see the matched groups)
This captures all lines with Y or N and ignores everything else:
^...(\d{3})\s*([YN])\s*(\d+:\d+)

RegEx: Uk Landlines, Mobile phone numbers

I've been struggling with finding a suitable solution :-
I need an regex expression that will match all UK phone numbers and mobile phones.
So far this one appears to cover most of the UK numbers:
^0\d{2,4}[ -]{1}[\d]{3}[\d -]{1}[\d -]{1}[\d]{1,4}$
However mobile numbers do not work with this regex expression or phone-numbers written in a single solid block such as 01234567890.
Could anyone help me create the required regex expression?
[\d -]{1}
is blatently incorrect: a digit OR a space OR a hyphen.
01000 123456
01000 is not a valid UK area code. 123456 is not a valid local number.
It is important that test data be real area codes and real number ranges.
^\s*(?(020[7,8]{1})?[ ]?[1-9]{1}[0-9{2}[ ]?[0-9]{4})|(0[1-8]{1}[0-9]{3})?[ ]?[1-9]{1}[0-9]{2}[ ]?[0-9]{3})\s*|[0-9]+[ ]?[0-9]+$
The above pattern is garbage for many different reasons.
[7,8] matches 7 or comma or 8. You don't need to match a comma.
London numbers also begin with 3 not just 7 or 8.
London 020 numbers aren't the only 2+8 format numbers; see also 023, 024, 028 and 029.
[1-9]{1} simplifies to [1-9]
[ ]? simplifies to \s?
Having found the intial 0 once, why keep searching for it again and again?
^(0....|0....|0....|0....)$ simplifies to ^0(....|....|....|....)$
Seriously. ([1]|[2]|[3]|[7]){1} simplifies to [1237] here.
UK phone numbers use a variety of formats: 2+8, 3+7, 3+6, 4+6, 4+5, 5+5, 5+4. Some users don't know which format goes with which number range and might use the wrong one on input. Let them do that; you're interested in the DIGITS.
Step 1: Check the input format looks valid
Make sure that the input looks like a UK phone number. Accept various dial prefixes, +44, 011 44, 00 44 with or without parentheses, hyphens or spaces; or national format with a leading 0. Let the user use any format they want for the remainder of the number: (020) 3555 7788 or 00 (44) 203 555 7788 or 02035-557-788 even if it is the wrong format for that particular number. Don't worry about unbalanced parentheses. The important part of the input is making sure it's the correct number of digits. Punctuation and spaces don't matter.
^\(?(?:(?:0(?:0|11)\)?[\s-]?\(?|\+)44\)?[\s-]?\(?(?:0\)?[\s-]?\(?)?|0)(?:\d{5}\)?[\s-]?\d{4,5}|\d{4}\)?[\s-]?(?:\d{5}|\d{3}[\s-]?\d{3})|\d{3}\)?[\s-]?\d{3}[\s-]?\d{3,4}|\d{2}\)?[\s-]?\d{4}[\s-]?\d{4}|8(?:00[\s-]?11[\s-]?11|45[\s-]?46[\s-]?4\d))(?:(?:[\s-]?(?:x|ext\.?\s?|\#)\d+)?)$
The above pattern matches optional opening parentheses, followed by 00 or 011 and optional closing parentheses, followed by an optional space or hyphen, followed by optional opening parentheses. Alternatively, the initial opening parentheses are followed by a literal + without a following space or hyphen. Any of the previous two options are then followed by 44 with optional closing parentheses, followed by optional space or hyphen, followed by optional 0 in optional parentheses, followed by optional space or hyphen, followed by optional opening parentheses (international format). Alternatively, the pattern matches optional initial opening parentheses followed by the 0 trunk code (national format).
The previous part is then followed by the NDC (area code) and the subscriber phone number in 2+8, 3+7, 3+6, 4+6, 4+5, 5+5 or 5+4 format with or without spaces and/or hyphens. This also includes provision for optional closing parentheses and/or optional space or hyphen after where the user thinks the area code ends and the local subscriber number begins. The pattern allows any format to be used with any GB number. The display format must be corrected by later logic if the wrong format for this number has been used by the user on input.
The pattern ends with an optional extension number arranged as an optional space or hyphen followed by x, ext and optional period, or #, followed by the extension number digits. The entire pattern does not bother to check for balanced parentheses as these will be removed from the number in the next step.
At this point you don't care whether the number begins 01 or 07 or something else. You don't care whether it's a valid area code. Later steps will deal with those issues.
Step 2: Extract the NSN so it can be checked in more detail for length and range
After checking the input looks like a GB telephone number using the pattern above, the next step is to extract the NSN part so that it can be checked in greater detail for validity and then formatted in the right way for the applicable number range.
^\(?(?:(?:0(?:0|11)\)?[\s-]?\(?|\+)(44)\)?[\s-]?\(?(?:0\)?[\s-]?\(?)?|0)([1-9]\d{1,4}\)?[\s\d-]+)(?:((?:x|ext\.?\s?|\#)\d+)?)$
Use the above pattern to extract the '44' from $1 to know that international format was used, otherwise assume national format if $1 is null.
Extract the optional extension number details from $3 and store them for later use.
Extract the NSN (including spaces, hyphens and parentheses) from $2.
Step 3: Validate the NSN
Remove the spaces, hyphens and parentheses from $2 and use further RegEx patterns to check the length and range and identify the number type.
These patterns will be much simpler, since they will not have to deal with various dial prefixes or country codes.
The pattern to match valid mobile numbers is therefore as simple as
^7([45789]\d{2}|624)\d{6}$
Premium rate is
^9[018]\d{8}$
There will be a number of other patterns for each number type: landlines, business rate, non-geographic, VoIP, etc.
By breaking the problem into several steps, a very wide range of input formats can be allowed, and the number range and length for the NSN checked in very great detail.
Step 4: Store the number
Once the NSN has been extracted and validated, store the number with country code and all the other digits with no spaces or punctuation, e.g. 442035557788.
Step 5: Format the number for display
Another set of simple rules can be used to format the number with the requisite +44 or 0 added at the beginning.
The rule for numbers beginning 03 is
^44(3\d{2})(\d{3])(\d{4})$
formatted as
0$1 $2 $3 or as +44 $1 $2 $3
and for numbers beginning 02 is
^44(2\d)(\d{4})(\d{4})$
formatted as
(0$1) $2 $3 or as +44 $1 $2 $3
The full list is quite long. I could copy and paste it all into this thread, but it would be hard to maintain that information in multiple places over time. For the present the complete list can be found at: http://aa-asterisk.org.uk/index.php/Regular_Expressions_for_Validating_and_Formatting_GB_Telephone_Numbers
Given that people sometimes write their numbers with spaces in random places, you might be better off ignoring the spaces all together - you could use a regex as simple as this then:
^0(\d ?){10}$
This matches:
01234567890
01234 234567
0121 3423 456
01213 423456
01000 123456
But it would also match:
01 2 3 4 5 6 7 8 9 0
So you may not like it, but it's certainly simpler.
Would this regex do?
// using System.Text.RegularExpressions;
/// <summary>
/// Regular expression built for C# on: Wed, Sep 8, 2010, 06:38:28
/// Using Expresso Version: 3.0.2766, http://www.ultrapico.com
///
/// A description of the regular expression:
///
/// [1]: A numbered capture group. [\+44], zero or one repetitions
/// \+44
/// Literal +
/// 44
/// [2]: A numbered capture group. [\s+], zero or one repetitions
/// Whitespace, one or more repetitions
/// [3]: A numbered capture group. [\(?]
/// Literal (, zero or one repetitions
/// [area_code]: A named capture group. [(\d{1,5}|\d{4}\s+?\d{1,2})]
/// [4]: A numbered capture group. [\d{1,5}|\d{4}\s+?\d{1,2}]
/// Select from 2 alternatives
/// Any digit, between 1 and 5 repetitions
/// \d{4}\s+?\d{1,2}
/// Any digit, exactly 4 repetitions
/// Whitespace, one or more repetitions, as few as possible
/// Any digit, between 1 and 2 repetitions
/// [5]: A numbered capture group. [\)?]
/// Literal ), zero or one repetitions
/// [6]: A numbered capture group. [\s+|-], zero or one repetitions
/// Select from 2 alternatives
/// Whitespace, one or more repetitions
/// -
/// [tel_no]: A named capture group. [(\d{1,4}(\s+|-)?\d{1,4}|(\d{6}))]
/// [7]: A numbered capture group. [\d{1,4}(\s+|-)?\d{1,4}|(\d{6})]
/// Select from 2 alternatives
/// \d{1,4}(\s+|-)?\d{1,4}
/// Any digit, between 1 and 4 repetitions
/// [8]: A numbered capture group. [\s+|-], zero or one repetitions
/// Select from 2 alternatives
/// Whitespace, one or more repetitions
/// -
/// Any digit, between 1 and 4 repetitions
/// [9]: A numbered capture group. [\d{6}]
/// Any digit, exactly 6 repetitions
///
///
/// </summary>
public Regex MyRegex = new Regex(
"(\\+44)?\r\n(\\s+)?\r\n(\\(?)\r\n(?<area_code>(\\d{1,5}|\\d{4}\\s+"+
"?\\d{1,2}))(\\)?)\r\n(\\s+|-)?\r\n(?<tel_no>\r\n(\\d{1,4}\r\n(\\s+|-"+
")?\\d{1,4}\r\n|(\\d{6})\r\n))",
RegexOptions.IgnoreCase
| RegexOptions.Singleline
| RegexOptions.ExplicitCapture
| RegexOptions.CultureInvariant
| RegexOptions.IgnorePatternWhitespace
| RegexOptions.Compiled
);
//// Replace the matched text in the InputText using the replacement pattern
// string result = MyRegex.Replace(InputText,MyRegexReplace);
//// Split the InputText wherever the regex matches
// string[] results = MyRegex.Split(InputText);
//// Capture the first Match, if any, in the InputText
// Match m = MyRegex.Match(InputText);
//// Capture all Matches in the InputText
// MatchCollection ms = MyRegex.Matches(InputText);
//// Test to see if there is a match in the InputText
// bool IsMatch = MyRegex.IsMatch(InputText);
//// Get the names of all the named and numbered capture groups
// string[] GroupNames = MyRegex.GetGroupNames();
//// Get the numbers of all the named and numbered capture groups
// int[] GroupNumbers = MyRegex.GetGroupNumbers();
Notice how the spaces and dashes are optional and can be part of it.. also it is now divided into two capture groups called area_code and tel_no to break it down and easier to extract.
Strip all whitespace and non-numeric characters and then do the test. It'll be musch , much easier than trying to account for all the possible options around brackets, spaces, etc.
Try the following:
#"^(([0]{1})|([\+][4]{2}))([1]|[2]|[3]|[7]){1}\d{8,9}$"
Starts with 0 or +44 (for international) - I;m sure you could add 0044 if you wanted.
It then has a 1, 2, 3 or 7.
It then has either 8 or 9 digits.
If you want to be even smarter, the following may be a useful reference: http://en.wikipedia.org/wiki/Telephone_numbers_in_the_United_Kingdom
It's not a single regex, but there's sample code from Braemoor Software that is simple to follow and fairly thorough.
The JS version is probably easiest to read. It strips out spaces and hyphens (which I realise you said you can't do) then applies a number of positive and negative regexp checks.
Start by stripping the non-numerics, excepting a + as the first character.
(Javascript)
var tel=document.getElementById("tel").value;
tel.substr(0,1).replace(/[^+0-9]/g,'')+tel.substr(1).replace(/[^0-9]/g,'')
The regex below allows, after the international indicator +, any combination of between 7 and 15 digits (the ITU maximum) UNLESS the code is +44 (UK). Otherwise if the string either begins with +44, +440 or 0, it is followed by 2 or 7 and then by nine of any digit, or it is followed by 1, then any digit except 0, then either seven or eight of any digit. (So 0203 is valid, 0703 is valid but 0103 is not valid). There is currently no such code as 025 (or in London 0205), but those could one day be allocated.
/(^\+(?!44)[0-9]{7,15}$)|(^(\+440?|0)(([27][0-9]{9}$)|(1[1-9][0-9]{7,8}$)))/
Its primary purpose is to identify a correct starting digit for a non-corporate number, followed by the correct number of digits to follow. It doesn't deduce if the subscriber's local number is 5, 6, 7 or 8 digits. It does not enforce the prohibition on initial '1' or '0' in the subscriber number, about which I can't find any information as to whether those old rules are still enforced. UK phone rules are not enforced on properly formatted international phone numbers from outside the UK.
After a long search for valid regexen to cover UK cases, I found that the best way (if you're using client side javascript) to validate UK phone numbers is to use libphonenumber-js along with custom config to reduce bundle size:
If you're using NodeJS, generate UK metadata by running:
npx libphonenumber-metadata-generator metadata.custom.json --countries GB --extended
then import and use the metadata with libphonenumber-js/core:
import { isValidPhoneNumber } from "libphonenumber-js/core";
import data from "./metadata.custom.json";
isValidPhoneNumber("01234567890", "GB", data);
CodeSandbox Example