lookbehind

问题 This question already has an answer here : Get more than 1 quotations in text paragraph in R regex (1 answer) Closed 5 years ago . I have data like this: Good afternoon. Hello. My bro's name is John... and he said softly 0.8% : "Don't you think I am handsome??" HAHA. jiji. koko. I would like to take get the sentence before the quotations, and text inside the quotation by using Look Behind regex in R. First: I want to look for quotation marks in a bunch of text. Second: Look back and extract 1

问题 This question already has an answer here : Get more than 1 quotations in text paragraph in R regex (1 answer) Closed 5 years ago . I have data like this: Good afternoon. Hello. My bro's name is John... and he said softly 0.8% : "Don't you think I am handsome??" HAHA. jiji. koko. I would like to take get the sentence before the quotations, and text inside the quotation by using Look Behind regex in R. First: I want to look for quotation marks in a bunch of text. Second: Look back and extract 1

问题 Very simple problem. I just need to capture some strings using a regex positive lookbehind, but I don't see a way to do it. Here's an example, suppose I have some strings: library(stringr) myStrings <- c("MFG: acme", "something else", "MFG: initech") I want to extract the words which are prefixed with "MFG:" > result_1 <- str_extract(myStrings,"MFG\\s*:\\s*\\w+") > > result_1 [1] "MFG: acme" NA "MFG: initech" That almost does it, but I don't want to include the "MFG:" part, so that's what a

问题 Very simple problem. I just need to capture some strings using a regex positive lookbehind, but I don't see a way to do it. Here's an example, suppose I have some strings: library(stringr) myStrings <- c("MFG: acme", "something else", "MFG: initech") I want to extract the words which are prefixed with "MFG:" > result_1 <- str_extract(myStrings,"MFG\\s*:\\s*\\w+") > > result_1 [1] "MFG: acme" NA "MFG: initech" That almost does it, but I don't want to include the "MFG:" part, so that's what a

问题 Very simple problem. I just need to capture some strings using a regex positive lookbehind, but I don't see a way to do it. Here's an example, suppose I have some strings: library(stringr) myStrings <- c("MFG: acme", "something else", "MFG: initech") I want to extract the words which are prefixed with "MFG:" > result_1 <- str_extract(myStrings,"MFG\\s*:\\s*\\w+") > > result_1 [1] "MFG: acme" NA "MFG: initech" That almost does it, but I don't want to include the "MFG:" part, so that's what a

问题 I need to match the string "foo" from a string with this format: string = "/foo/boo/poo" I tied this code: poo = "poo" foo = re.match('.*(?=/' + re.escape(poo) + ')', string).group(0) and it gives me /foo/boo as the content of the variable foo (instead of just foo/boo ). I tried this code: poo = "poo" foo = re.match('(?=/).*(?=/' + re.escape(poo) + ')', string).group(0) and I'm getting the same output ( /foo/boo instead of foo/boo ). How can I match only the foo/boo part? 回答1: Hey try the

问题 I use python regular expressions ( re module) in my code and noticed different behaviour in theese cases: re.findall(r'\s*(?:[a-z]\))?[^.)]+', 'a) xyz. b) abc.') # non-capturing group # results in ['a) xyz', ' b) abc'] and re.findall(r'\s*(?<=[a-z]\))?[^.)]+', 'a) xyz. b) abc.') # lookbehind # results in ['a', ' xyz', ' b', ' abc'] What I need to get is just ['xyz', 'abc'] . Why are the examples behave differently and how t get the desired result? 回答1: The reason a and b are included in the

问题 How can I use lookbehind in a C# Regex in order to skip matches of repeated prefix patterns? Example - I'm trying to have the expression match all the b characters following any number of a characters: Regex expression = new Regex("(?<=a).*"); foreach (Match result in expression.Matches("aaabbbb")) MessageBox.Show(result.Value); returns aabbbb , the lookbehind matching only an a . How can I make it so that it would match all the a s in the beginning? I've tried Regex expression = new Regex("(

问题 I'm trying to retrieve the category part this string " property_id=516&category=featured-properties ", so the result should be "featured-properties", and I came up with a regular expression and tested it on this website http://gskinner.com/RegExr/, and it worked as expected, but when I added the regular expression to my javascript code, I had a "Invalid regular expression" error, can anyone tell me what is messing up this code? Thanks! var url = "property_id=516&category=featured-properties"

问题 I'm trying to retrieve the category part this string " property_id=516&category=featured-properties ", so the result should be "featured-properties", and I came up with a regular expression and tested it on this website http://gskinner.com/RegExr/, and it worked as expected, but when I added the regular expression to my javascript code, I had a "Invalid regular expression" error, can anyone tell me what is messing up this code? Thanks! var url = "property_id=516&category=featured-properties"