I have the following list of strings:
name <- c("hsa-miR-555p","hsa-miR-519b-3p","hsa-let-7a")
What I want to do is for each of the above strings
replace the text after second delimiter (-) with "zzz".
Yielding:
hsa-miR-zzz
hsa-miR-zzz
hsa-let-zzz
What's the way to do it?
Might as well use something like:
gsub("^((?:[^-]*-){2}).*", "\\1zzz", name)
(?:[^-]*-) is a non-capturing group which consists of several non-dash characters followed by a single dash character and the {2} just after means this group occurs twice only. Then, match everything else for the replacement. Note I used an anchor just in case to avoid unintended substitutions.
Perhaps something like this:
> gsub("([A-Za-z]+-)([A-Za-z]+-)(.*)", "\\1\\2zzz", name)
[1] "hsa-miR-zzz" "hsa-miR-zzz" "hsa-let-zzz"
There are actually several ways to approach this, depending on how "regular" your expressions actually are. For example, do they all start with "hsa-"? What are the options for the "middle" group? Might there be more than three dashes?
Related
I want to select some string combination (with dots(.)) from a very long string (sql). The full string could be a single line or multiple line with new line separator, and this combination could be in start (at first line) or a next line (new line) or at both place.
I need help in writing a regex for it.
Examples:
String s = I am testing something like test.test.test in sentence.
Expected output: test.test.test
Example2 (real usecase):
UPDATE test.table
SET access = 01
WHERE access IN (
SELECT name FROM project.dataset.tablename WHERE name = 'test' GROUP BY 1 )
Expected output: test.table and project.dataset.tablename
, can I also add some prefix or suffix words or space which should be present where ever this logic gets checked. In above case if its update regex should pick test.table, but if the statement is like select test.table regex should not pick it up this combinations and same applies for suffix.
Example3: This is to illustrate the above theory.
INS INTO test.table
SEL 'abcscsc', wu_id.Item_Nbr ,1
FROM test.table as_t
WHERE as_t.old <> 0 AND as_t.date = 11
AND (as_t.numb IN ('11') )
Expected Output: test.table, test.table (Key words are INTO and FROM)
Things Not Needed in selection:as_t.numb, as_t.old, as_t.date
If I get the regex I can use in program to extract this word.
Note: Before and after string words to the combination could be anything like update, select { or(, so we have to find the occurrence of words which are joined together with .(dot) and all the number of such occurrence.
I tried something like this:
(?<=.)(.?)(?=.)(.?) -: This only selected the word between two .dot and not all.
.(?<=.)(.?)(?=.)(.?). - This everything before and after.
To solve your initial problem, we can just use some negation. Here's the pattern I came up with:
[^\s]+\.[^\s]+
[^ ... ] Means to make a character class including everything except for what's between the brackets. In this case, I put \s in there, which matches any whitespace. So [^\s] matches anything that isn't whitespace.
+ Is a quantifier. It means to find as many of the preceding construct as you can without breaking the match. This would happily match everything that's not whitespace, but I follow it with a \., which matches a literal .. The \ is necessary because . means to match any character in regex, so we need to escape it so it only has its literal meaning. This means there has to be a . in this group of non-whitespace characters.
I end the pattern with another [^\s]+, which matches everything after the . until the next whitespace.
Now, to solve your secondary problem, you want to make this match only work if it is preceded by a given keyword. Luckily, regex has a construct almost specifically for this case. It's called a lookbehind. The syntax is (?<= ... ) where the ... is the pattern you want to look for. Using your example, this will only match after the keywords INTO and FROM:
(?<=(?:INTO|FROM)\s)[^\s]+\.[^\s]+
Here (?:INTO|FROM) means to match either the text INTO or the text FROM. I then specify that it should be followed by a whitespace character with \s. One possible problem here is that it will only match if the keywords are written in all upper case. You can change this behavior by specifying the case insensitive flag i to your regex parser. If your regex parser doesn't have a way to specify flags, you can usually still specify it inline by putting (?i) in front of the pattern, like so:
(?i)(?<=(?:INTO|FROM)\s)[^\s]+\.[^\s]+
If you are new to regex, I highly recommend using the www.regex101.com website to generate regex and learn how it works. Don't forget to check out the code generator part for getting the regex code based on the programming language you are using, that's a cool feature.
For your question, you need a regex that understands any word character \w that matches between 0 and unlimited times, followed by a dot, followed by another series of word character that repeats between 0 and unlimited times.
So here is my solution to your question:
Your regex in JavaScript:
const regex = /([\w][.][\w])+/gm;
in Java:
final String regex = "([\w][.][\w])+";
in Python:
regex = r"([\w][.][\w])+"
in PHP:
$re = '/([\w][.][\w])+/m';
Note that: this solution is written for your use case (to be used for SQL strings), because now if you have something like '.word' or 'word..word', it will still catch it which I assume you don't have a string like that.
See this screenshot for more details
I have two possible endings for my string. The first with no numbers:
http://www.something.com/test.html
the second with numbers (up to two digits)
http://www.something.com/test-1.html
http://www.something.com/test-2.html
http://www.something.com/test-3.html
http://www.something.com/test-4.html
http://www.something.com/test-15.html
I need to strip the .html from the first case and -1.html (or whatever number) from the second. The idea is to make the two string comparable to find duplicates.
I think the following should manage the second case
gsub("-[0-9]|[1-9][0-9].html", "", string)
but is it possible to have a function to manage both cases?
You can perhaps use something like this:
(-[0-9]+)?\\.html
Note that it's safer to escape the dot because an unescaped dot will match any character.
regex101 demo
I am trying to get at least three words separated by two commas.I have so far managed to match two words with one comma with
/([A-z]|[0-9])(,{1})([A-z]|[0-9])/
but how can I add a comma and a word to this.I have tried repeating the same but did not work.
/^(?:\w+,){2,}(?:\w+)$/
This will get you a comma separated list of at least 3 words ([a-zA-Z0-9_]+).
/^\s*(?:\w+\s*,\s*){2,}(?:\w+\s*)$/
This is a slightly more user-friendly version of the first, allowing spaces in between words.
If it's a PERL derived regex, as most implementations I've encountered, /[^,]+(?:,[^,]+){2,}/ tests well against anything that has at least two commas in it, providing that the commas have something between them. The (?:) construct allows to group without capturing. The {2,} construct specifies 2 or more matches of the previous group. In javascript, you can test it:
/[^,]+(?:,[^,]+){2,}/.test("hello,world,whats,up,next"); // returns true
/[^,]+(?:,[^,]+){2,}/.test("hello,world"); // returns false
Try this one:
([a-zA-Z0-9]+)(,[a-zA-Z0-9]+){2,}
Few general suggestions from performance perspective:
Don't use [ ]|[ ] clause - you can just put few character classes inside one [ ], e.g. [A-Za-z0-9]
Don't overuse () - usually each of them stores captured argument which requires additional overhead. If you just need to group few pieces together look for grouping operator that does not store match (it might be something like (?: ... ) )
This will solve your problem,
try this
([a-zA-Z0-9],[a-zA-Z0-9],([a-zA-Z0-9]))
I have the need to check whether strings adhere to a particular ID format.
The format of the ID is as follows:
aBcDe-fghIj-KLmno-pQRsT-uVWxy
A sequence of five blocks of five letters upper case or lower case, separated by one dash.
I have the following regular expression that works:
string idFormat = "[a-zA-Z]{5}[-]{1}[a-zA-Z]{5}[-]{1}[a-zA-Z]{5}[-]{1}[a-zA-Z]{5}[-]{1}[a-zA-Z]{5}";
Note that there is no trailing dash, but the all of the blocks within the ID follow the same format. Therefore, I would like to be able to represent this sequence of four blocks with a trailing dash inside the regular expression and avoid the duplication.
I tried the following, but it doesn't work:
string idFormat = "[[a-zA-Z]{5}[-]{1}]{4}[a-zA-Z]{5}";
How do I shorten this regular expression and get rid of the duplicated parts?
What is the best way to ensure that each block does also not contain any numbers?
Edit:
Thanks for the replies, I now understand the grouping in regular expressions.
I'm running a few tests against the regular expression, the following are relevant:
Test 1: aBcDe-fghIj-KLmno-pQRsT-uVWxy
Test 2: abcde-fghij-klmno-pqrst-uvwxy
With the following regular expression, both tests pass:
^([a-zA-Z]{5}-){4}[a-zA-Z]{5}$
With the next regular expression, test 1 fails:
^([a-z]{5}-){4}[a-z]{5}$
Several answers have said that it is OK to omit the A-Z when using a-z, but in this case it doesn't seem to be working.
You can try:
([a-z]{5}-){4}[a-z]{5}
and make it case insensitive.
If you can set regex options to be case insensitive, you could replace all [a-zA-Z] with just plain [a-z]. Furthermore, [-]{1} can be written as -.
Your grouping should be done with (, ), not with [, ] (although you're correctly using the latter in specifying character sets.
Depending on context, you probably want to throw in ^...$ which matches start and end of string, respectively, to verify that the entire string is a match (i.e. that there are no extra characters).
In javascript, something like this:
/^([a-z]{5}-){4}[a-z]{5}$/i
This works for me, though you might want to check it:
[a-zA-Z]{5}(-[a-zA-Z]{5}){4}
(One group of five letters, followed by [dash+group of five letters] four times)
([a-zA-Z]{5}[-]{1}){4}[a-zA-Z]{5}
Try
string idFormat = "([a-zA-Z]{5}[-]{1}){4}[a-zA-Z]{5}";
I.e. you basically replace your brackets by parentheses. Brackets are not meant for grouping but for defining a class of accepted characters.
However, be aware that with shortened versions, you can use the expression for validating the string, but not for analyzing it. If you want to process the 5 groups of characters, you will want to put them in 5 groups:
string idFormat =
"([a-zA-Z]{5})-([a-zA-Z]{5})-([a-zA-Z]{5})-([a-zA-Z]{5})-([a-zA-Z]{5})";
so you can address each group and process it.
how can I write regular expression that dose not contain some string at the end.
in my project,all classes that their names dont end with some string such as "controller" and "map" should inherit from a base class. how can I do this using regular expression ?
but using both
public*.class[a-zA-Z]*(?<!controller|map)$
public*.class*.(?<!controller)$
there isnt any match case!!!
Do a search for all filenames matching this:
(?<!controller|map|anythingelse)$
(Remove the |anythingelse if no other keywords, or append other keywords similarly.)
If you can't use negative lookbehinds (the (?<!..) bit), do a search for filenames that do not match this:
(?:controller|map)$
And if that still doesn't work (might not in some IDEs), remove the ?: part and it probably will - that just makes it a non-capturing group, but the difference here is fairly insignificant.
If you're using something where the full string must match, then you can just prefix either of the above with ^.* to do that.
Update:
In response to this:
but using both
public*.class[a-zA-Z]*(?<!controller|map)$
public*.class*.(?<!controller)$
there isnt any match case!!!
Not quite sure what you're attempting with the public/class stuff there, so try this:
public.*class.*(?<!controller|map)$`
The . is a regex char that means "anything except newline", and the * means zero or more times.
If this isn't what you're after, edit the question with more details.
Depending on your regex implementation, you might be able to use a lookbehind for this task. This would look like
(?<!SomeText)$
This matches any lines NOT having "SomeText" at their end. If you cannot use that, the expression
^(?!.*SomeText$).*$
matches any non-empty lines not ending with "SomeText" as well.
You could write a regex that contains two groups, one consists of one or more characters before controller or map, the other contains controller or map and is optional.
^(.+)(controller|map)?$
With that you may match your string and if there is a group() method in the regex API you use, if group(2) is empty, the string does not contain controller or map.
Check if the name does not match [a-zA-Z]*controller or [a-zA-Z]*map.
finally I did it in this way
public.*class.*[^(controller|map|spec)]$
it worked