Currently I am learning how to work with HL7 and how to parse it in python. Now I was wondering what happens if a value in a HL7 segment contains a pipe sign, e.g. '|'. How is this sign handled? If there is no masking, it would lead to a crash of the HL7 parser. Is there a masking possibility?
\F\
You should read the relevant sections of chapter 2 of the version 2 standard about how escaping works in version 2.
The HL7 structure has defined escape sequences for the separators like |.
When you look at a HL7 message, the used five delimiters are right after the MSH:
MSH|^~\&
| is the Field separator F
^ the component separator S
~ is the repetition separator (for the second level elements) R
\ is the escape character E
& is the sub-component separator T
So to escape one of the special characters like |, you have to take the escape character and then add the defined letter (F,S, etc.)
So in above case, to escape the | you would have to put \F\. Or escaping the escape character is \E\.
If you like you can also change the delimiters after the MSH completely, but I don't recommend that.
Related
If you try **b.**a on https://spec.commonmark.org/dingus/, you would see its b. is not bolded.
However, if you just omit the last a, it works.
What is the CommonMark format to bold it correctly (that is bolded a., followed by unbolded b)?
The solution to format the text correctly in CommonMark.
According to section 6.2 of the CommonMark specification, that behaviour is by design:
A delimiter run is either a sequence of one or more * characters [...]
A right-flanking delimiter run is a delimiter run that is (1) not preceded by Unicode whitespace, and either (2a) not preceded by a Unicode punctuation character, or (2b) preceded by a Unicode punctuation character and followed by Unicode whitespace or a Unicode punctuation character.
You can get the desired visual appearance with **b.**a, where is the HTML entity "zero-width joiner", thus:
**b.**a
...and we've just found a bug in the rendering here on Stack Overflow. In edit mode, the preview shows it correctly as
I am tryng to get rid of shortcodes inside a Google Sheet column. I have many items such as [spacer type="1" height="20"][spacer] or [FinalTilesGallery id="37"] I just would like to cancel them. Is there any simple way to do it?
Thanks !
For in-place replacement, the quick option would be to use the Find and Replace dialog (Ctrl + H) with Search Using Regular Expressions turned on, which is more powerful than your standard Find and Replace.
Find: \[.*?\] - Match anything within an open-bracket up to the very next close-bracket. This should work assuming you have no nested brackets, e.g. [[no][no]].
If you do have nested brackets, you'll have to change this to \[[^\[\]]*\]. And continue to Replace All until all the codes are gone.
Replace: Nothing.
Replace All. If you don't want to affect other sheets that may be in your document, make sure you select the right range to work with, too.
This just erases everything within the brackets.
If you want to erase any redundant spaces left by this, simply Find and Replace again (with Regular Expressions) on + (space and plus), which will match 1 or more spaces and replace with (single space).
E.g.:
string [] [] string2 -> string string2 after the shortcode replacement.
After replacing spaces, it will become string string2.
Let's say your original strings are in the range A2:A. Place the following into B2 of an otherwise completely empty Column B (or the second cell of any other empty column):
=ArrayFormula(IF(A2:A="",,TRIM(REGEXREPLACE(A2:A,"\[[^\[\]]+\]",""))))
I can't see your data, so I don't know what kind of information is between these shortcodes. If you find that this leaves you with concatenated pieces of data where there should be spaces between them, replace the above with this version:
=ArrayFormula(IF(A2:A="",,TRIM(REGEXREPLACE(SUBSTITUTE(SUBSTITUTE(A2:A,"["," ["),"]","] "),"\[[^\[\]]+\]",""))))
I can't teach regular expression language here. But I will note that, since square brackets have specific meaning within regex, your literal square brackets must be indicated with the escape character: the backslash.
Here is the regex expression alone:
\[[^\[\]]+\]
The opening \[ and the closing \], then, reference your actual opening and closing bracket sets. If we remove those, we have this left:
[^\[\]]+
Again, you see the escaped opening and closing square brackets, which I'll replace with the word these:
[^these]+
What remains there are opening and closing brackets with regex meaning, i.e., "anything in this group." And the circumflex symbol ^ as the first character within this set of square brackets means "anything except." The + symbol means "in any string length of one or more characters."
So that whole regex expression then reads: "A literal open square bracket, followed by one or more characters that are anything except square brackets, ending with a literal closing square bracket."
And we are REGEXREPLACE-ing any instance of that with "" (i.e., nothing).
I need a regular expression able to match everything but a string starting with a specific pattern (specifically index.php and what follows, like index.php?id=2342343).
Regex: match everything but:
a string starting with a specific pattern (e.g. any - empty, too - string not starting with foo):
Lookahead-based solution for NFAs:
^(?!foo).*$
^(?!foo)
Negated character class based solution for regex engines not supporting lookarounds:
^(([^f].{2}|.[^o].|.{2}[^o]).*|.{0,2})$
^([^f].{2}|.[^o].|.{2}[^o])|^.{0,2}$
a string ending with a specific pattern (say, no world. at the end):
Lookbehind-based solution:
(?<!world\.)$
^.*(?<!world\.)$
Lookahead solution:
^(?!.*world\.$).*
^(?!.*world\.$)
POSIX workaround:
^(.*([^w].{5}|.[^o].{4}|.{2}[^r].{3}|.{3}[^l].{2}|.{4}[^d].|.{5}[^.])|.{0,5})$
([^w].{5}|.[^o].{4}|.{2}[^r].{3}|.{3}[^l].{2}|.{4}[^d].|.{5}[^.]$|^.{0,5})$
a string containing specific text (say, not match a string having foo):
Lookaround-based solution:
^(?!.*foo)
^(?!.*foo).*$
POSIX workaround:
Use the online regex generator at www.formauri.es/personal/pgimeno/misc/non-match-regex
a string containing specific character (say, avoid matching a string having a | symbol):
^[^|]*$
a string equal to some string (say, not equal to foo):
Lookaround-based:
^(?!foo$)
^(?!foo$).*$
POSIX:
^(.{0,2}|.{4,}|[^f]..|.[^o].|..[^o])$
a sequence of characters:
PCRE (match any text but cat): /cat(*SKIP)(*FAIL)|[^c]*(?:c(?!at)[^c]*)*/i or /cat(*SKIP)(*FAIL)|(?:(?!cat).)+/is
Other engines allowing lookarounds: (cat)|[^c]*(?:c(?!at)[^c]*)* (or (?s)(cat)|(?:(?!cat).)*, or (cat)|[^c]+(?:c(?!at)[^c]*)*|(?:c(?!at)[^c]*)+[^c]*) and then check with language means: if Group 1 matched, it is not what we need, else, grab the match value if not empty
a certain single character or a set of characters:
Use a negated character class: [^a-z]+ (any char other than a lowercase ASCII letter)
Matching any char(s) but |: [^|]+
Demo note: the newline \n is used inside negated character classes in demos to avoid match overflow to the neighboring line(s). They are not necessary when testing individual strings.
Anchor note: In many languages, use \A to define the unambiguous start of string, and \z (in Python, it is \Z, in JavaScript, $ is OK) to define the very end of the string.
Dot note: In many flavors (but not POSIX, TRE, TCL), . matches any char but a newline char. Make sure you use a corresponding DOTALL modifier (/s in PCRE/Boost/.NET/Python/Java and /m in Ruby) for the . to match any char including a newline.
Backslash note: In languages where you have to declare patterns with C strings allowing escape sequences (like \n for a newline), you need to double the backslashes escaping special characters so that the engine could treat them as literal characters (e.g. in Java, world\. will be declared as "world\\.", or use a character class: "world[.]"). Use raw string literals (Python r'\bworld\b'), C# verbatim string literals #"world\.", or slashy strings/regex literal notations like /world\./.
You could use a negative lookahead from the start, e.g., ^(?!foo).*$ shouldn't match anything starting with foo.
You can put a ^ in the beginning of a character set to match anything but those characters.
[^=]*
will match everything but =
Just match /^index\.php/, and then reject whatever matches it.
In Python:
>>> import re
>>> p='^(?!index\.php\?[0-9]+).*$'
>>> s1='index.php?12345'
>>> re.match(p,s1)
>>> s2='index.html?12345'
>>> re.match(p,s2)
<_sre.SRE_Match object at 0xb7d65fa8>
Came across this thread after a long search. I had this problem for multiple searches and replace of some occurrences. But the pattern I used was matching till the end. Example below
import re
text = "start![image]xxx(xx.png) yyy xx![image]xxx(xxx.png) end"
replaced_text = re.sub(r'!\[image\](.*)\(.*\.png\)', '*', text)
print(replaced_text)
gave
start* end
Basically, the regex was matching from the first ![image] to the last .png, swallowing the middle yyy
Used the method posted above https://stackoverflow.com/a/17761124/429476 by Firish to break the match between the occurrence. Here the space is not matched; as the words are separated by space.
replaced_text = re.sub(r'!\[image\]([^ ]*)\([^ ]*\.png\)', '*', text)
and got what I wanted
start* yyy xx* end
Does anyone understand what this (([A-Za-z\\s])+)\\? means?
I wonder why it should be "\\s" and "\\" ?
If I entered "\s", Xcode just doesn't understand and if I entered "\?", it just doesn't match the "?".
I have googled a lot, but I did not find a solution. Anyone knows?
The actual regex is (([A-Za-z\s])+)\?. This matches one or more letters and whitespace characters followed by an question mark. The \ has two different meanings here. In the first instance \s has a fixed meaning and stands for any white space characters. In the second instance the \? means the literal question mark character. The escaping is necessary as the question mark means one or none of the previous otherwise.
You can't type your regex like this in a string literal in C code though. C also does some escaping using the backslash character. For example "\n" is translated to a string containing only a newline character. There are some other escape sequences with special meanings. If the character after the backslash doesn't have a special meaning the backslash is just removed. That means if you want to have a single backspace in your string you have to write two.
So if you wrote your regex string as you wanted you'd get different results as it would be interpreted as (([A-Za-zs])+)? which has a completely different meaning. So when you write a regex in an ObjC (or any other C-based language) string literal you must double all backslash characters.
not sure about ios but same thing happens in java. \ is escape character for java,and c also so when you type \s java reads \ as an escape character.
think of it as if you want to print a \ what will you have to do.
you will have to type \\. now first \ will work as escape character for java and second one will be printed.
I think it should be the same concept for ios too.
so if you want \s you type \s, if you want \ you type \\.
The \s metacharacter is used to find a whitespace character.
Refer this!
Could anybody help me make a proper regular expression from a bunch of text in Ruby. I tried a lot but I don't know how to handle variable length titles.
The string will be of format <sometext>title:"<actual_title>"<sometext>. I want to extract actual_title from this string.
I tried /title:"."/ but it doesnt find any matches as it expects a closing quotation after one variable from opening quotation. I couldn't figure how to make it check for variable length of string. Any help is appreciated. Thanks.
. matches any single character. Putting + after a character will match one or more of those characters. So .+ will match one or more characters of any sort. Also, you should put a question mark after it so that it matches the first closing-quotation mark it comes across. So:
/title:"(.+?)"/
The parentheses are necessary if you want to extract the title text that it matched out of there.
/title:"([^"]*)"/
The parentheses create a capturing group. Inside is first a character class. The ^ means it's negated, so it matches any character that's not a ". The * means 0 or more. You can change it to one or more by using + instead of *.
I like /title:"(.+?)"/ because of it's use of lazy matching to stop the .+ consuming all text until the last " on the line is found.
It won't work if the string wraps lines or includes escaped quotes.
In programming languages where you want to be able to include the string deliminator inside a string you usually provide an 'escape' character or sequence.
If your escape character was \ then you could write something like this...
/title:"((?:\\"|[^"])+)"/
This is a railroad diagram. Railroad diagrams show you what order things are parsed... imagine you are a train starting at the left. You consume title:" then \" if you can.. if you can't then you consume not a ". The > means this path is preferred... so you try to loop... if you can't you have to consume a '"' to finish.
I made this with https://regexper.com/#%2Ftitle%3A%22((%3F%3A%5C%5C%22%7C%5B%5E%22%5D)%2B)%22%2F
but there is now a plugin for Atom text editor too that does this.