pattern-matching

问题 I found out reading the spec that scala supports binding type variables when doing a type pattern match: Map(1 -> "one", 2 -> "two") match { case l: Map[k, v] => // binds k to Int and v to String // k and v are types as shown here: val i: Iterator[Tuple2[k, v]] = l.iterator println(i.mkString(", ")) } Are there any fancy things or practical things I can do with this? Or binding type variables is only useful for type documentation purpose? It occurred to me that Scala sometimes needs type

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . I seek a state of the art algorithms to approximate string matching. Do you offer me references(article, thesis,...)? thank you 回答1: You might want to read about Levenshtein distance. http://en.wikipedia.org/wiki/Levenshtein_distance 回答2: You might have got your answer already but I want to convey my points on

问题 I have a .fastq file formatted in the following way @M01790:39:000000000-C3C6P:1:1101:14141:1618 1:N:0:8 (name) AACATCTACATATTCACATATAGACATGAAACACCTGTGGTTCTTCCTCAGTATGTAGGACTGTAACATAG (sequence) + GGACCCGGGGGGGGGDGGGFGGGGGGFGGGGGGGGGGGFGGGGFGFGFFFGGGGGGFGGGGGGGGGGGFGG (quality) For each sequence the format is the same (repetition of 4 lines) What I am trying to do is searching for specific regex pattern in a window of n=35 characters of the 2nd line, cut it if found and report it at the end

问题 How could I request a certain digit with a certain times to be inserted in an input element? I need to request from The users to input three times a certain digit, let we say number 9, in the text or password field, in any format.. How could I do that using HTML5 or any other way? If I had this code: <td><input type="password" name="password" maxlength="9" pattern="\d+" title="9 numbers only" placeholder="9 numbers only" value="<?php echo htmlentities($password); ?>" /></td> Then, my required

问题 It might be similar question asked in this forum but I feel my requirement peculiar. I have a data frame df1 where it consists of variable "WrittenTerms" with 40,000 observations and I have another data-fame df2 with variable "SuggestedTerms" with 17,000 observations I need to calculate the similarity between "written Term" and "suggestedterms" df1$WrittenTerms head pain lung cancer abdminal pain df2$suggestedterms cardio attack breast cancer abdomen pain head ache lung cancer I need to get

问题 I am looking for a way to list all possible patterns from a finite regex (with no duplicates). Is there any source available? 回答1: Although it won't cover some advanced features, and has its own share of other caveats, Regexp::Genex seems to be close to what you are looking for. There's also this thread of PerlMonks which is relevant enough (as well as explaining how Regexp::Genex might not do for you, and some roll-yourself alternatives). Otherwise, as per Jeffrey Friedl's Mastering Regular

问题 Imagine a quadtree defined as follow: data (Eq a, Show a) => QT a = C a | Q (QT a) (QT a) (QT a) (QT a) deriving (Eq, Show) bad1 = Q u u u u where u = C 255 bad2 = Q (C 0) (C 255) (Q u u u u) (C 64) where u = C 255 The constructor allows you to create not well-formed quadtrees. bad1 should be simply C 255 and bad2 is not valid too because its bottom-right quadtree (for the same reason, it should be Q (C 0) (C 255) (C 244) (C 64) . So far so good. Checking its well-formness is simply a matter

问题 Imagine a quadtree defined as follow: data (Eq a, Show a) => QT a = C a | Q (QT a) (QT a) (QT a) (QT a) deriving (Eq, Show) bad1 = Q u u u u where u = C 255 bad2 = Q (C 0) (C 255) (Q u u u u) (C 64) where u = C 255 The constructor allows you to create not well-formed quadtrees. bad1 should be simply C 255 and bad2 is not valid too because its bottom-right quadtree (for the same reason, it should be Q (C 0) (C 255) (C 244) (C 64) . So far so good. Checking its well-formness is simply a matter

问题 My codes looks like this: 1::2::Nil match { case 1::ts::Nil => "Starts with 1. More than one element" case 1::Nil => "Starts with 1. Only one element" } I tried to use 1::ts::Nil to match the List who starts with 1 and whose length is greater than 1. It workes well for 2-element list, however, this pattern doesn't work for 3-element list , for example: 1::2::3::Nil match { case 1::ts::Nil => "Starts with 1. More than one element" case 1::Nil => "Starts with 1. Only one element" } This won't

问题 I've seen a few other questions and answers stating that let _ = foo() destroys the result at the end of the statement rather than at scope exit, which is what let _a = foo() does. I am unable to find any official description of this, nor any rationale for this syntax. I'm interested in a few inter-twined things: Is there even a mention of it in the official documentation? What is the history behind this choice? Is it simply natural fall-out from Rust's binding / destructuring rules? Is it