Re: Sum up second elemsts of pairs in a sequence by grouping by the first item in pair
Just one more way to solve it but, getting a hash-map as a result (- [[1 0.5] [1 0.7] [2 1.0] [3 0.1] [3 0.1]] (map (partial apply hash-map)) (apply merge-with +)) Em quinta-feira, 19 de março de 2015 19:02:28 UTC-3, Ambrose Bonnaire-Sergeant escreveu: user= (def a (group-by first [[1 0.5] [1 0.7] [2 1.0] [3 0.1] [3 0.1]])) #'user/a user= (for [[k vs] a] [k (apply + (map second vs))]) ([1 1.2] [2 1.0] [3 0.2]) On Thu, Mar 19, 2015 at 3:41 PM, Alex updat...@gmail.com javascript: wrote: Hello everybody, How to transform sequence *[[1 0.5] [1 0.7] [2 1.0] [3 0.1] [3 0.1]]* to *[[1 1.2] [2 1.0] [3 0.2]]* ? Best regards, Alex -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@googlegroups.com javascript: Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+u...@googlegroups.com javascript: For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+u...@googlegroups.com javascript:. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: Streaming a large file onto a channel
Hi Adrian, What is exactly the issue that you're facing? I did my own version and it seems to be working fine. Please, take a look and I hope it helps. (defn process-file [ch file] (async/thread (with-open [input (io/reader file)] (doseq [line (line-seq input)] (async/!! ch line) (defn parse [line] (str Parsed: line)) ; change it to do whatever you want (defn mapping [ch] (async/map parse [ch])) (defn start [] (let [events (mapping (async/chan))] (process-file events 10_events.json) (async/go-loop [] (let [v (async/! events)] (println v) (recur) About your approach. For me, it seems a legitimate usage for core.async. Please, send us your impressions once you finish. Cheers, Em terça-feira, 17 de março de 2015 09:52:17 UTC-3, Adrian Mowat escreveu: Hi, I've played around with core.async a bit but now I'm trying to use it for a real project and I'm running into a problem getting data off a file and into a channel on the JVM (i.e. as opposed to ClojureScript) I have around 1GB of data sitting in a file. Each line of the file contains a separate JSON document. There are different types of document in the file and I would like use core.async to setup a pipeline of concurrent operations as follows so I can start processing the data before I've finished reading the file. 1. Stream the raw data out of the file one line at a time, parse it as JSON and write each line to channel (1) 2. Read channel (1) and divide the messages up by type and write them to new channels (2..n) 3. Read channels (2..n) and apply business logic as appropriate I'd like the initial read to run in it's own thread because it will be IO blocking. The others can run in core.async's thread pool I'm running into problems getting channels (1) and (2) to talk to one another. Here's my initial spike and I would expect it to write the 10 lines of json from the example file to stdout. (defn file-to-chan [ch file] (do (async/thread (with-open [rdr (io/reader file)] (doseq [line (line-seq rdr)] (!! ch line ch)) (defn parse-line [s] (json/parse-string s (comp keyword str/lower-case))) (def events (chan 1 (map parse-line))) (go (while true (println (! events (file-to-chan events 10_events.json) I have a few questions... * Can anyone help me understand what's going wrong? (I'm sure it's something silly, but I'm going cross eyed looking at it) * It's effectively a batch process. Is this an appropriate use case for core.async? * If so, am I on the right track or is there a better way to approach this? Many Thanks Adrian -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
