pattern-matching

问题 I'm attempting to match only the content between opening/closing paragraph tags. Playing around with it on RegExr, I can get <p.*?> to match an opening paragraph tag that may or may not have any additional attributes such as class and/or ID. However, when I attempt to add that pattern to a positive look behind, it breaks and I'm not sure why. I've tried escaping the < and > symbols, but that doesn't seem to help. The look ahead, however, works perfectly. Here's an example of the entire

问题 I'm attempting to match only the content between opening/closing paragraph tags. Playing around with it on RegExr, I can get <p.*?> to match an opening paragraph tag that may or may not have any additional attributes such as class and/or ID. However, when I attempt to add that pattern to a positive look behind, it breaks and I'm not sure why. I've tried escaping the < and > symbols, but that doesn't seem to help. The look ahead, however, works perfectly. Here's an example of the entire

问题 I have a table posts : CREATE TABLE posts ( id serial primary key, content text ); When a user submits a post, how can I compare his post with the others and find similar posts? I'm looking for something like StackOverflow does with the "Similar Questions". 回答1: While Text Search is an option it is not meant for this type of search primarily. The typical use case would be to find words in a document based on dictionaries and stemming, not to compare whole documents. I am sure StackOverflow

问题 Why i am not able to find the match? >>> ti = "abcd" >>> tq = "abcdef" >>> check_abcd = re.compile('^abcd') >>> if check_abcd.search(ti) is check_abcd.search(tq): ... print "Matching" ... else: ... print "not matching" ... not matching Eventhough both variables ti and tq are matching and having same reference >>> print check_abcd.search(ti) <_sre.SRE_Match object at 0x7ffbb05559f0> >>> print check_abcd.search(tq) <_sre.SRE_Match object at 0x7ffbb05559f0> Why it is not matching? 回答1: `is` is

问题 I have the following regex, that I would like to pattern match in Scala 2.13 . The regex: \/brokers\/ids\/\d{1,}$ The following string, that is going to be validate: scala> ("echo dump" #| "nc localhost 32773" #| "grep brokers").!! res2: String = " /brokers/ids/1 " How can I do it in Scala 2.13? 回答1: Scala 2.13 introduced interpolated string patterns, so you could avoid using regex and just do: "/brokers/ids/1" match { case s"/brokers/ids/$ids" => ids //return 1 } 来源： https://stackoverflow

问题 Hi I have dataframe with 2 columns : +----------------------------------------+----------+ | Text | Key_word | +----------------------------------------+----------+ | First random text tree cheese cat | tree | | Second random text apple pie three | text | | Third random text burger food brain | brain | | Fourth random text nothing thing chips | random | +----------------------------------------+----------+ I want to generate a 3rd columns with a word appearing before the key_word from the

问题 I'm trying to get the N-th row after a given pattern with awk. The problem is that awk searches pattern literally: awk -v patt=${1} -v rows=${2}'NR==p {print} /patt/ {p=NR+rows}' How to escape the "patt" valiable ? 回答1: Use the awk matching operator instead of the slashes: awk -v patt=${1} -v rows=${2} 'NR==p {print} $0 ~ patt {p=NR+rows}' 回答2: I've maneged to get it work,with double quotes patt=${1} awk -v rows=${2} "NR==p {print} /${patt}/ {p=NR+rows}" $3 回答3: There's nothing special about

问题 I have an application where I want to track 2 objects at a time that are rather small in the picture. This application should be running on Android and iPhone, so the algorithm should be efficient. For my customer it is perfectly fine if we deliver some patterns along with the software that are attached to the objects to be tracked to have a well-recognizable target. This means that I can make up a pattern on my own. As I am not that much into image processing yet, I don't know which objects

问题 I define a point type TimeSeriesPoint<'T> = { Time : DateTimeOffset Value : 'T } and a series type TimeSeries<'T> = TimeSeriesPoint<'T> list where I assume the points in this list are ordered by time. I am trying to zip two time series, where, in general, they will have points with the same time, but there might be some points missing in either of them. Any idea why I get a warning for incomplete pattern matches in the code below? let zip (series1 : TimeSeries<float>) (series2 : TimeSeries

问题 I am new to scala with a java background. Is there a way to pattern match super classes (or traits) in a class inheritance tree with leafs as case classes and nodes abstract classes or traits? As far as I know case class inheritance is not allowed. I think that pattern matching abstract classes in large inheritance tree would be very helpful In the following code the last case in the match statement errors during compilation sealed trait Person { def name: String } case class Customer(name: