sequences

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 10 years ago . Some people don't like sequences on Oracle. Why? I think they are very easy to use and so nice. You can use them in select, inserts,

问题 I'm still on Snow Leopard (I know...) so forgive if this is fixed in one of the later versions of OS/X, but I want to do standard "seq" aka: for i in `seq 1 100` ; do cat /whatever > $i.txt ; done I thought installing GNU tools would do it, but apparently not. 回答1: On my mac both of these work (OS X 10.8.5) Andreas-Wederbrands-MacBook-Pro:~ raven$ for i in {1..10}; do echo $i; done 1 2 3 4 5 6 7 8 9 10 Andreas-Wederbrands-MacBook-Pro:~ raven$ for i in `seq 1 10`; do echo $i; done 1 2 3 4 5 6

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 12 months ago . I'm interested in automatic music making. I was thinking about a program that is fed a large number of 1-bar arpeggios (= fixed length sequences of notes, for simplicity) and generates its own sequences, based on what it learnt. To start with, I know I could use letter (digram?

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 12 months ago . I'm interested in automatic music making. I was thinking about a program that is fed a large number of 1-bar arpeggios (= fixed length sequences of notes, for simplicity) and generates its own sequences, based on what it learnt. To start with, I know I could use letter (digram?

问题 I am not using Single in LINQ below, but I am still getting a 'Sequence contains no elements' exception: allNames = StockCollection.Where((s) => s.Name.IndexOf("A") == 0) .Select((s) => s.Name) .Aggregate((namesInfo, name) => namesInfo += ", " + name); This exception comes when there is no stock starting with name 'A' . It seems that one extension method is expecting atleast one element satisfying the condition but that's not expected. Can you please suggest the best solution to resolve this?

问题 We have an increasing sequence in which each element is consist of even digits only (0, 2, 4, 6, 8). How can we find the nth number in this sequence Is it possible to find nth number in this sequence in O(1) time. Sequence: 0, 2, 4, 6, 8, 20, 22, 24, 26, 28, 40, 42, 44, 46, 48, 60, 62, 64, 66, 68, 80, 82, 84, 86, 88, 200, 202 and so on. 回答1: The nth number in this sequence is n in base 5, with the digits doubled. def base5(n): if n == 0: return for x in base5(n // 5): yield x yield n % 5 def

问题 Can you suggest simpler and clearer way to write this function? let cartesian_product sequences = let step acc sequence = seq { for x in acc do for y in sequence do yield Seq.append x [y] } Seq.fold step (Seq.singleton Seq.empty) sequences 回答1: Less elegant, but (seems to be) faster solution: let cartesian_product2 sequences = let step acc sequence = seq { for x in acc do for y in sequence do yield seq { yield! x ; yield y } } Seq.fold step (Seq.singleton Seq.empty) sequences ; > cartesian

问题 I'm converting a db from postgres to mysql. Since i cannot find a tool that does the trick itself, i'm going to convert all postgres sequences to autoincrement ids in mysql with autoincrement value. So, how can i list all sequences in a Postgres DB ( 8.1 version) with information about the table in which it's used, the next value etc with a SQL query? Be aware that i can't use the information_schema.sequences view in the 8.4 release. 回答1: The following query gives names of all sequences.

问题 I have this "learning code" I wrote for the morris seq in f# that suffers from stack overflow that I don't know how to avoid. "morris" returns an infinite sequence of "see and say" sequences (i.e., {{1}, {1,1}, {2,1}, {1,2,1,1}, {1,1,1,2,2,1}, {3,1,2,2,1,1},...}). let printList l = Seq.iter (fun n -> printf "%i" n) l printfn "" let rec morris s = let next str = seq { let cnt = ref 1 // Stack overflow is below when enumerating for cur in [|0|] |> Seq.append str |> Seq.windowed 2 do if cur.[0]

问题 First, I assume each structure-specific sequences would have different ways to remove an item: Vectors could be by index, List could be remove first or last, Set should be passing of the actual item to remove, etc. Second, I assume there are some methods for removal that are structure agnostic; they work on seq interface. Since sequences are immutable in Clojure, I suspect what you're actually doing is making a cheap copy of the original, only without the original item. This means list