It seems I am not able to understand something very basic with preg regex Patterns in PHP.
What is the difference between these Regex Patterns:
\b([A-Z...]...)
[\b]{1}([A-Z...]...)
The Pattern should start with a word boundary, but why is the result different, when I put it in []{1} ??
The first one works like I expected, but the second not. The problem is, that I want to put more into the [], so that the pattern can start with a word boundary OR a small character [a-z].
Thank you!
Example Text:
Race1529/05/201512:45K4 Senior Men 1000m
LaneName(s)NFBib(s)TimeRank250m500m750m
152
Martin SCHUBERT / Lukas REUSCHENBACH155
11
153
151Kostja STROINSKI / Kai SPENNER
03:07.740
GER
8
I want to find the names of the racers. Sometimes they have a word-break (\b) at the beginning, sometimes not. (But i need the word-break.)
$pattern = '#\b(['.$GB.$KB.'\s\-]{2,40})\s(['.$GB.'\'\-\s]{2,40})[0-9]{0,5}#';
($GB is a variable with all Uppercase Letters, $KB with lower case letters)
preg_match_all gives me all racers where the Name has a word-break at the beginning. (In this example Schubert, Reuschenbach, Spenner) but of course not Stroinski. So, I try this:
$pattern = '#[\b0-9]+(['.$GB.$KB.'\s\-]{2,40})\s(['.$GB.'\'\-\s]{2,40})[0-9]{0,5}#';
Does not work. Even if i remove the 0-9 and only put [\b]{1} at the beginning it doesn't find any hit.
I don't see the difference between \b and [\b]{1}. It seems to be a very basic misunderstanding.
The [\b] is a character class that only matches a backspace char (\u0008).
See PHP regex reference:
note that "\b" has a different meaning, namely the backspace character, inside a character class
Also, .{1} = ., the {1} limiting quantifier is always redundant and only makes sense when your patterns are built dynamically from variables.
Related
I have a regex in PHP that replaces everything I don't want with spaces
/[^a-z0-9\p{L}]/siu
But there is this one exception, I want to keep punctuations for abbreviations.
Example:
F.B.I.Federal.Bureau.of.Investigation => 'F B I Federal Bureau of
Investigation'
S.W.A.T.Team => 'S W A T Team'
Should be:
F.B.I.Federal.Bureau.of.Investigation => 'F.B.I. Federal Bureau of
Investigation'
S.W.A.T.Team => 'S.W.A.T. Team'
PHP code:
$s = "F.B.I.Federal.Bureau.of.Investigation";
return preg_replace('/[^a-z0-9\p{L}]/siu', " ", $s);
so the logic is, that it should check the second char of first match, and if it's an '.' char, then don't replace.
Not sure if this is possible with regex, then I would appreciate an alternative with PHP.
Actually, there are many types of abbreviations, and as Jon Stirling says, there is no really 100% working solution here since you need a whole list of possible abbreviations to filter out. You may have a peek at some fancy regex solution by #ndn and grab the pattern part related to abbreviations there.
If you need to only handle patterns like in the question, you may consider using
'~(\b(?:\p{Lu}\.){2,})|[^0-9\p{L}]~u'
or - if D.Word should also be treated as an abbreviation:
'~(\b(?:\p{Lu}\.)+)|[^0-9\p{L}]~u'
and replace with '$1 '. See the regex demo.
Pattern details:
(\b(?:\p{Lu}\.)+) - Group 1 (later referenced with $1 backreference): 1 or more consequent occurrences of any Unicode uppercase letter and a dot after it
| - or
[^0-9\p{L}] - any char that is not an ASCII digit and a Unicode letter.
And here is a variant of a regex with #ndn's abbreviations:
'~\b((?:[Ee]tc|St|Gen|Hon|Prof|Dr|Mr|Ms|Mrs|[JS]r|Col|Maj|Brig|Sgt|Capt|Cmnd|Sen|Rev|Rep|Revd|pp|[Vv]iz|i\.?\s*e|[Vvol]|[Rr]col|maj|Lt|[Ff]ig|[Ff]igs|[Vv]iz|[Vv]ols|[Aa]pprox|[Ii]ncl|Pres|[Dd]ept|min|max|[Gg]ovt|lb|ft|c\.?\s*f|vs|\p{Lu}(?:\.\p{Lu})+)\.)|[^0-9\p{L}]~'
See the regex demo.
If you do not want to remove -, ( and ), just make sure to add them to the negated character class, replace [^0-9\p{L}] with [^0-9\p{L}()-].
Feel free to update by adding more abbreviations or enhance by shrinking the alternatives.
I am trying to detect with regex, strings that have a pattern of {any_number}{x-}{large|medium|small} for a site with clothing I am building in PHP.
I have managed to match the sizes against a preconfigured set of strings by using:
$searchFor = '7x-large';
$regex = '/\b'.$searchFor.'\b/';
//Basically, it's finding the letters
//surrounded by a word-boundary (the \b bits).
//So, to find the position:
preg_match($regex, $opt_name, $match, PREG_OFFSET_CAPTURE);
I even managed to detect weird sizes like 41 1/2 with regex, but I am not an expert and I am having a hard time on this.
I have come up with
preg_match("/^(?<![\/\d])([xX\-])(large|medium|small)$/", '7x-large', $match);
but it won't work.
Could you pinpoint what I am doing wrong?
It sounds like you also want to match half sizes. You can use something like this:
$theregex = '~(?i)^\d+(?:\.5)?x-(?:large|medium|small)$~';
if (preg_match($theregex, $yourstring,$m)) {
// Yes! It matches!
// the match is $m[0]
}
else { // nah, no luck...
}
Note that the (?i) makes it case-insensitive.
This also assumes you are validating that an entire string conforms to the pattern. If you want to find the pattern as a substring of a larger string, remove the ^ and $ anchors:
$theregex = '~(?i)\d+(?:\.5)?x-(?:large|medium|small)~';
Look at the specification you have and build it up piece by piece. You want "{any_number}{x-}{large|medium|small}".
"{any_number}" would be \d+. This does not allow fractional numbers such as 12.34, but the question does not specify whether they are required.
"{x-}" is a simple string x-
"{large|medium|small}" is a choice between three alternatives large|medium|small.
Joining the pieces together gives \d+x-(large|medium|small). Note the brackets around the alternation, without then the expression would be interpreted as (\d+x-large)|medium|small.
You mention "weird sizes like 41 1/2" but without specifying how "weird" the number to be matched are. You need a precise specification of what you include in "weird" before you can extend the regular expression.
As this question, I can split strings that includes upper cases like this:
function splitAtUpperCase($string){
return preg_replace('/([a-z0-9])?([A-Z])/','$1 $2',$string);
}
$string = 'setIfUnmodifiedSince';
echo splitAtUpperCase($string);
Output is "set If Unmodified Since"
But I need some modification:
That code snippet doesn't handle the cases, when these characters exist in string: ÇÖĞŞÜİ. I don't want to transliterate the characters. Then I lose meaning of word. I need to use some UTF characters. That code makes "HereÇonThen" to "HereÇon Then"
I also don't want to split uppercase abbreviations. If word is "IKnowYouWillComeASAPHere" I need it to be converted to "I Know You Will Come ASAP Here"
Don't explode if all letters are uppercase. Like "DONTCOMEHERE"
Explode also numeric values. "Before2013ends" to "Before 2013 ends"
Explode if first character is hash key (#).
cases and expected results
"comeHEREtomorrow" => "come HERE tomorrow"
"KissYouTODAY" => "kiss you TODAY"
"comeÜndeHere" => "come Ünde Here"
"NEVERSAYIT" => "NEVERSAYIT"
"2013willCome" => "2013 will Come"
"Before2013ends" => "Before 2013 ends"
"IKnowThat" => "I Know That"
"#whatiknow" => "# whatiknow"
For these cases I use subsequent str_replace operations. I look for a short solution that doesn't make too much for loops to check the words. It would be better to have it as preg_replace or etc. if possible.
Edit: Anyone can try his solution by changing convert function inside this PHP fiddle: http://ideone.com/9gajZ8
/([[:lower:][:digit:]])?([[:upper:]]+)/u should do it.
Here /u is used for Unicode characters. and ([[:upper:]]+) is used for Sequence of upper cased letters.
Note. Case of a letter depends on the character set you are using.
Some notes:
Use Unicode properties to search for upper-case & lower-case letters (and even title-case ones, f.ex. Dž Lj Nj Dz)
comeHEREtomorrow & IKnowThat won't work with one method, until you use some dictionaries to find exact words.
Because if you want to translate comeHEREtomorrow as come HERE tomorrow, IKnowThat will be IK now That (or even IK now T hat);
And if you want to translate IKnowThat as I Know That, comeHEREtomorrow will be come H E R E tomorrow
My solution: http://ideone.com/oALyTo (excludes non-letter & non-number charaters)
Well, I matched all of your test cases, but I still don't think it's a good solution. (One of the few flaws in test driven design).
I took a slightly different approach. Instead of trying to write a regular expression for what the place between a word should look like, I wrote a regular expression that looks for everything that apparently is a word, and then imploded.
function convert($keyword) {
$wResult = preg_match_all('/(^I|[[:upper:]]{2,}|[[:upper:]][[:lower:]]*|[[:lower:]]+|\d+|#)/u', $keyword, $matches);
return implode(' ',$matches[0]);
}
As you can see, this is what I decided qualified as a word:
^I A capital I at the beginning of the string. Break point: Icons.
[[:upper:]]{2,} Consecutive capitals. Break Point: WellIKnowThat
[[:upper:]][[:lower:]]* A single Capital followed by some lower case letters
[[:lower:]]+ A string of lower case letters
\d+ A string of digits
# A literal #
It's not perfect - there're still many breakpoints. You can continue to refine these word definitions, but frankly, there's always going to be an edge case you can't catch. Then you wind up slowly expanding this regular expression until it's totally unmanageable. You could try using a dictionary, but that breaks down eventually, too. What do you do with "whirlwind"? Or "ITan"? Is that "IT an", or "I Tan"? Case in point? Here it is after I tried to catch some of My errors. It's getting so huge, and it's still trivial to come up with strings it breaks on. This function is all about degrees - how much time is it worth spending to teach your algorithm all the funny points of all the world languages?
EDIT: After some work, And deciding that I could be separated out as its own word if and only if it was followed immediately by One Capital letter and one lower case letter, I've updated my attempt at an answer.
function convert($keyword, $debug = false) {
$wResult = preg_match_all('/I(?=[[:upper:]][[:lower:]])|[[:upper:]]{2,}|[[:upper:]][[:lower:]]*|[[:lower:]]+|\d+|#/u', $keyword, $matches);
if($debug){
var_dump($matches);
var_dump($matches[0]);
var_dump(implode(' ',$matches[0]));
}
return implode(' ',$matches[0]);
}
I also added some new test cases:
convert("Icons") = "Icons"
convert("WellIKnowThat") == "Well I Know That"
convert("ITan") == "I Tan"
convert("whirlwind") == "whirlwind"
I think this is about as good as it's going to get today. The final set of "Word Definitions" in order of preference, is:
Upper case I, provided it's followed by an upper case letter and a lower case letter:I(?=[[:upper:]][[:lower:]])
Two or more consecutive upper case letters: [[:upper:]]{2,}
A single uppercase Letter, followed by as many Lower case letters as possible: [[:upper:]][[:lower:]]*
one or more consecutive lower case letters: [[:lower:]]+
One or more consecutive digits: \d+
A literal pound symbol: #
I've added another word definition, a test case, and refined the testing fiddle. The new word definition matches the rule for I, but with A - the only other one letter word in the English Language.
you need Unicode Regex:
\p{Lu} for upercase and \p{Li} for lowercase
Hence, your usage will look like this:
/([\p{Ll}0-9])?([\p{Lu}])/
I found some partial help but cannot seem to fully accomplish what I need. I need to be able to do the following:
I need an regular expression to replace any 1 to 3 character words between two words that are longer than 3 characters with a match any expression:
For example:
walk to the beach ==> walk(.*)beach
If the 1 to 3 character word is not preceded by a word that's longer than 3 characters then I want to translate that 1 to 3 letter word to '<word> ?'
For example:
on the beach ==> on ?the ?beach
The simpler the rule the better (of course, if there's an alternative more complicated version that's more performant then I'll take that as well as I eventually anticipate heavy usage eventually).
This will be used in a PHP context most likely with preg_replace. Thus, if you can put it in that context then even better!
By the way so far I have got the following:
$string = preg_replace('/\s+/', '(.*)', $string);
$string = preg_replace('/\b(\w{1,3})(\.*)\b/', '${1} ?', $string);
but that results in:
walk to the beach ==> 'walk(.*)to ?beach'
which is not what I want. 'on the beach' seems to translate correctly.
I think you will need two replacements for that. Let's start with the first requirement:
$str = preg_replace('/(\w{4,})(?: \w{1,3})* (?=\w{4,})/', '$1(.*)', $str);
Of course, you need to replace those \w (which match letters, digits and underscores) with a character class of what you actually want to treat as a word character.
The second one is a bit tougher, because matches cannot overlap and lookbehinds cannot be of variable length. So we have to run this multiple times in a loop:
do
{
$str = preg_replace('/^\w{0,3}(?: \w{0,3})* (?!\?)/', '$0?', $str, -1, $count);
} while($count);
Here we match everything from the beginning of the string, as long as it's only up-to-3-letter words separated by spaces, plus one trailing space (only if it is not already followed by a ?). Then we put all of that back in place, and append a ?.
Update:
After all the talk in the comments, here is an updated solution.
After running the first line, we can assume that the only less-than-3-letter words left will be at the beginning or at the end of the string. All others will have been collapsed to (.*). Since you want to append all spaces between those with ?, you do not even need a loop (in fact these are the only spaces left):
$str = preg_replace('/ /', ' ?', $str);
(Do this right after my first line of code.)
This would give the following two results (in combination with the first line):
let us walk on the beach now go => let ?us ?walk(.*)beach ?now ?go
let us walk on the beach there now go => let ?us ?walk(.*)beach(.*)there ?now ?go
I have a string that contains 5 words. In the string one of the words is a Ham Radio Call Sign and can be anyone of the thousands of call signs in the US. In order to extract the Call Sign from the string I need to utilize the below pattern. The Call Sign I need to extract can be in any of the 5 positions in the string. The number is never the first character and the number is never the last character. The string is actually put together from an Array since it is originally read from a text file.
$string = $word[1] $word[2] $word[3] etc....
So the search can be either done on the whole string or each piece of the array.
Patterns:
1 Number and 3 Letters Example: AB4C A4BC
1 Number and 4 Letters Example: A4BCD
1 Number and 5 Letters Example: AB4CDE
I have tried everything I can think of and search till I cant search no more. I am sure I am over thinking this.
A two-step regular expression like this would do it:
$str = "hello A4AB there BC5AD";
$signs = array();
preg_match_all('/[A-Z][A-Z\d]{1,3}[A-Z]/', $str, $possible_signs);
foreach($possible_signs[0] as $possible_sign)
if (preg_match('/^\D+\d\D+$/', $possible_sign))
array_push($signs, $possible_sign);
print_r($signs); //Array ([0] => A4AB [1] => BC5AD)
Explanation
This is a regular expression approach, using two patterns. I don't think it could be done with one and still satisfy the exact requirements of the matching rules.
The first pattern enforces the following requirements:
substring starts and ends with a capital letter
substring contains only other capital letters or numbers between the first and last letter
substring is, overall, not more than 6 characters long
What I can't do in that same pattern, for complex REGEX reasons I won't go into (unless someone knows a way and can correct me), is enforce that only one number is contained.
#jeroen's answer does enforce this in a single pattern, but in turn does not enforce the correct length of the substring. Either way, we need a second pattern.
So after grabbing the initial matches, we loop over the results. We then apply each to a second pattern that enforces simply that there is only one number in the substring.
If so, we green-light the substring and it's added to the $signs array.
Hope this helps.
It depends on what the other words can contain, but you could use a regular expression like:
#\b[a-z]+\d[a-z]+\b#i
^ case insensitive
^^ a word boundary
^^^^^^ One or more letters
^^ One number
You can make it more restrictive by using {1,3} instead of + for the letters so that you have a sequence of 1 to 3 letters.
The complete expression would be something like:
$success = preg_match('#\b[a-z]+\d[a-z]+\b#i', $input_string, $matches);
where $matches[0] will contain the matched value, see the manual.