Hello, I'm new in clojure and lisp, and I have problem with making
this code elegant (or at least short).
This is Floyd-Warshall algorithm - very simple algorithm in imperative
form (3 nested for loops).
In clojure the best I've get so far is this monstrosity:
(defn create-graph [nodes distance
> [snip]
>
> You are "accumulating" a result, which hints us at 'reduce.
> And 'for provides the nested enumeration:
>
> (defn floyd-warshall2 [{:keys [nodes distances]}]
> (reduce (fn [[distances prevs] [k x y]]
> (let [d (+ (distances [x k] Double/POSITIVE_INFINITY)
>
I'm beginner myself, but I' think it's because it creates 100 new
classes (for each new anonymous fn).
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I was probably wrong - too many classes should throw error about
permGenSpace (at least in java they do).
Also for me it works for n=100, fails for 1000 (clojurebox
1.0).
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Hello.
I've tried to translate nice Hilbert-curve-index calculating function
to clojure (http://blog.notdot.net/2009/11/Damn-Cool-Algorithms-
Spatial-indexing-with-Quadtrees-and-Hilbert-Curves).
I've got sth like that:
(def hilbert-map {
:a {[0 0] [0 :d], [0 1] [1 :a], [1 0] [3 :b], [1 1] [2 :
> > I would like to somehow hide the global hilbert-map into my function,
> > but I can't see how to do that.
>
> Just put the literal directly into the function.
>
> > Is this possible? I know that I can just inert literal into my let,
> > but that degrades performance, when function is called man
> Eeeuw.
>
> Was this with a Clojure literal in the let, or with a non-trivial
> calculation using constants?
The only difference is literal map of maps in let form.
Full code here: http://clojure.pastebin.com/m17b8d69
I have to install java one more time, when I try to start java -
server, I ge
On 15 Lis, 00:21, John Harrop wrote:
> On Sat, Nov 14, 2009 at 3:03 PM, ajuc wrote:
> > I have to install java one more time, when I try to start java -
> > server, I get:
> > Error: no `server' JVM at `F:\Program Files\Java\jre6\bin\server
> > \jvm.dll
> That's very odd.
>
> Rich needs to take a look at this. Letting a constant shouldn't have a
> performance hit, IMO.
>
> Could you test whether it's faster to use your complex data structure
> directly in the function, anonymously at the point of use, or to yank it
> from a global var?
Code (can
On 16 Lis, 01:32, Alex Osborne wrote:
> Clojure's name gives a hint as to how do this: use a closure. :-) Just
> pull the let outside the defn:
>
> (let [hilbert-map {...}]
> (defn point-to-hilbert [...]
> ...))
Now it seems so obvious :).
I guess I don't think functional yet.
Thank yo
On 20 Lis, 01:49, nchubrich wrote:
> While we're on the topic, where is something like (subtract [1 2 3 3 4
> 4 5 6] evens) -> (1 3 3 5)? Doesn't seem to be in seq-utils or API.
> Seems like there should be a parallel "multiset" library for colls, to
> clojure.set. (I guess there could be two ve
On 22 Lis, 13:09, bOR_ wrote:
> Ontopic: I might be missing something, but is there an obvious way to
> do something like "lein src/chlamydia.clj" when I'm in the projects'
> directory ("chlamydia"), to run a script as in "java -server
> clojure.main chlamydia.clj"? I didn't see anything in the
(p(x) is true for all x in set X)
is equivalent to
(there are no such x in set X that p(x) is not true)
So IMHO it's good that (every? pred []) returns true.
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I would write this like that:
(def v #{[1 2 3] [9 8 3] [1 2] [1] [1 0 3 4] [1 2 3 4 5]} )
(defn better-match [pattern match1 match2]
;;here choosing better matching vec from these 2 - sorry, I'm too
lazy :)
)
(reduce #(better-match [1 2 3] %1 %2) [] v)
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I don't know if I understan correctly the requirements, but this is my
try.
(def v #{[1 2 3] [9 8 3] [1 2] [1] [1 0 3 4] [1 2 3 4 5]} )
(defn matching [p v]
(reduce + (map #(if (= %1 %2) 1 0) p v)))
(defn better-match [p v1 v2]
(if
(or
(> (matching p v1) (matching p v2))
On 28 Gru, 20:57, Robert Campbell wrote:
> How might I add a third and final condition, where those candidates
> with equal scores AND equal counts are all returned together?
Reduce can work with functions like
f : x * y -> x
So we can modify function closest to be like that (untested):
(clos
Maybe sth like that
(defn assoc-in-maybe-creating [coll keys creator-fns value] ...)
so it can be used:
(assoc-in-maybe-creating
[ {:a (sorted-map :X 1, :Y 2, :Z 3)
:c (sorted-map :X 1, :Z 3)}
{:b (sorted-map :X 1, :Y 2, :Z 3)}
{:f (sorted-map :X 1, :Y 2)}]
[0 :b :X]
[vector
Setq isn't functional - equivalent in clojure would be def, but it
isn't meant to be used in that way.
For your purpose there is better fit: postwalk-replace
http://richhickey.github.com/clojure/clojure.walk-api.html#clojure.walk/postwalk-replace
Greetings.
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+1 to safe-by-default.
I use clojure for games, but if it will be possible to easily make
computations fast, safe-by-default is more important.
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Look at Penumbra:
http://github.com/ztellman/penumbra
Greetings.
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Note that posts from new members are moderated - please be patient with you
On 23 Lip, 01:51, Paul Mooser wrote:
> Why not simply do:
>
> (defn fib [n]
> (println "called with " n)
> (if (> n 2)
> (+ (fib (- n 2)) (fib (- n 1)))
> 1))
>
> (def fib (memoize fib))
>
> I inserted the println to verify when we were actually calling the
> function, and I believe t
On 9 Wrz, 14:30, Stefan Rohlfing wrote:
> In order to get some more insight into recursion I wrote the following
> function but ended up in confusion:
>
> (defn prefix->postfix [expr]
> (if (coll? expr)
> (let [ [op arg1 arg2] expr]
> [ (prefix->postfix arg1) (prefix->postfix arg2) o
On 9 Wrz, 15:27, Stefan Rohlfing wrote:
> The indentation was correct by got messed up when I copying the code.
>
> This is how I interpret the function:
> 'expr' is only returned if (coll? expr) returns 'false', with is not
> the case with an argument such as '(+ 2 4).
> Next, this expression i
On 9 Wrz, 14:25, Andrew Gwozdziewycz wrote:
> The fact that Lisp macros actually operate on the AST means that Lisp
> macros can make *changes* to the AST (insert things, remove things,
> rearrange things), and *not* just substitute FOO for BAR. This is a
> hell of a lot more powerful.
>
> --htt
On 2 Sty, 12:01, Konrad Hinsen wrote:
> On 2 Jan 2011, at 03:29, Sunil S Nandihalli wrote:
>
> > can I force the JIT to be called immediately for certain pieces of
> > code after it starts executing with out waiting for the JVM realize
> > it is necessary? I would not mind jitting the who
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