How do I translate the loop part of Common Lisp code into Clojure? ... functional orientation -

-

how translate loop part of working common lisp (sbcl v.1.2.3) code clojure (v.1.6)? bit frustrated after working on hours/days without results. somewhere don't functional orientation suppose ...

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; unconditional entropy ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;  ;; probabilities (setq list_occur_prob '()) ;; init  ;; set probabilities want calculate entropy (setq list_occur_prob '(1/2 1/3 1/6)) ;;  ;; function calculate unconditional ;; entropy h = -sigma i=0,n (pi*log2(pi) ;; bits persymbol. (setq entropy 0) ;; init (setq entropy (loop in list_occur_prob    y = (* (log_base2 i) i)      collect y                  )) (setq entropy (* -1 (apply '+ entropy))) ;; change sign  ;; print unconditional entropy in bits per symbol. (print entropy) ;; btw, here entropy 1.4591479 bits per symbol.

they key operation need map transforms sequence using function. in entropy example gave, following should work:

(def probabilities [1/2 1/3 1/6])   (defn log [base x]   (/ (math/log x) (math/log base)))   (defn entropy [probabilities]     (->> probabilities          (map #(* (log 2 %) %)) ; note  - #(f %) shorthand (fn [x] (f x))          (reduce +)          (-)))   (entropy probabilities)  ; => 1.459

when working collections, pipeline operator (->>) used show sequence of operations. find easier read nested bracket syntax, if there lots of operations.

here, we're first mapping pi * log2(pi) function on sequence, , summing using (reduce +)


Comments

Post a Comment

Popular posts from this blog

java - Plugin org.apache.maven.plugins:maven-install-plugin:2.4 or one of its dependencies could not be resolved -

-
i getting error message , further 1 here: failed read artifact descriptor org.apache.maven.plugins:maven-install-plugin:jar:2.4: even though when go .m2 repository path c:\users\a591024.m2\repository\org\apache\maven\plugins\maven-resources-plugin\2.4 the maven-resources-plugin-2.4.jar file there , maven-resources-plugin-2.4.pom there. have tried delete .m2 repository no luck. far maven not build project desperately need to. any ideas? it seems proxy issue please aad following in setting.xml grabbing lan setting , proxy information. <proxies> <proxy> <id>proxy</id> <active>true</active> <protocol>http</protocol> <host>hostname</host> <port>port</port> </proxy> </proxies> this frequent issue, please see below link well. plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or 1 of dependencies not resolved maven: failed ret...
Read more

Round ImageView Android -

-
Image
i working on android application in doing rounded image view. working fine images, images 160x120 resolution shows oval shaped. code custom imageview given below, please me out here: public class roundimage extends drawable { private final bitmap mbitmap; private final paint mpaint; private final rectf mrectf; private final int mbitmapwidth; private final int mbitmapheight; public roundimage(bitmap bitmap) { mbitmap = bitmap; mrectf = new rectf(); mpaint = new paint(); mpaint.setantialias(true); mpaint.setdither(true); final bitmapshader shader = new bitmapshader(bitmap, shader.tilemode.clamp, shader.tilemode.clamp); mpaint.setshader(shader); mbitmapwidth = mbitmap.getwidth(); mbitmapheight = mbitmap.getheight(); } @override public void draw(canvas canvas) { canvas.drawoval(mrectf, mpaint); } @override protected void onboundschange(rect bound...
Read more

How can I utilize Yahoo Weather API in android -

-
Image
i want develop app using yahoo weather api android. want current , forecast weather details. i have tried different sources (e.g.: https://github.com/survivingwithandroid/weatherlib , getting error weatherlib api android , unable execute activity in android weatherlib ) , getting different errors m unable resplve. there can proper tutorial or guide! error: -17 08:50:48.961 3168-3168/com.survivingwithandroid.weather e/androidruntime﹕ fatal exception: main process: com.survivingwithandroid.weather, pid: 3168 java.lang.runtimeexception: unable start activity componentinfo{com.survivingwithandroid.weather/com.survivingwithandroid.weather.mainactivity}: java.lang.nullpointerexception: attempt invoke interface method 'boolean java.util.list.isempty()' on null object reference @ android.app.activitythread.performlaunchactivity(activitythread.java:2298) @ android.app.activitythread.handlelaunchactivity(activitythread.java:2360) @ android.app.activi...
Read more