Clojure Mentions
I thought some folks on this list might be interested in a mention graph I put up. It shows the # mentions of clojure across several sources (twitter, blogs, etc). http://twitpic.com/5nm8ve -- 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
Re: ordered map in Clojure?
ArrayMap? http://clojure.org/data_structures#toc21 James On Sat, Jun 25, 2011 at 1:55 PM, Alex Baranosky alexander.barano...@gmail.com wrote: What are some options for having a map that guarantees ordering of its keys in Clojure? (note: sorted-map won't do!) My first try was to use LinkedHashMap, but am running into exceptions of the java.util.LinkedHashMap cannot be cast to clojure.lang.Associative variety. So then I tried to use extend-type LinkedHashMap to Associative. Then I received the error message: interface clojure.lang.Associative is not a protocol ... makes sense :) So now that I've gone through all of that, which was fun while it lasted, could any of you help me figure out how to use a map that guarantees the entries are in the order they were entered? Thanks for the help! Alex -- 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 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
Re: last and nth are bad?
Per the doc, last is linear time, and the source doesn't check for reversible.
user= (source last)
(def
^{:arglists '([coll])
:doc Return the last item in coll, in linear time
:added 1.0}
last (fn last [s]
(if (next s)
(recur (next s))
(first s
unless i'm missing something with multimethod or protocol magic :)
On Thu, Jun 9, 2011 at 10:49 PM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
as long as (reversible? of-whatever-collection) is true , last is almost a
constant time operation
On Fri, Jun 10, 2011 at 8:20 AM, clojurefanxx neuzhou...@gmail.com wrote:
i'm a newbie working thru 4clojure.com's problems #19 thru #21 where
i'm asked to write a function, which when given a list or vector,
returns the last, penultimate, or an arbitrary nth element,
respectively.
for problem #19 (return last element), using the function last was not
accepted as a good solution for both lists and vectors, but the
following was accepted:
user= (#(nth % (- (count %) 1)) '(5 4 3))
3
user= (#(nth % (- (count %) 1)) '[1 2 3 4 5])
5
for problem #21, (return arbitrary element) , using the function nth
or get was not accepted.
-
Write a function which returns the Nth element from a sequence.
(= (__ '(4 5 6 7) 2) 6)
(= (__ [:a :b :c] 0) :a)
(= (__ [1 2 3 4] 1) 2)
(= (__ '([1 2] [3 4] [5 6]) 2) [5 6])
i think using the nth or get functions on vectors to return an element
at index position n should be fine performance-wise,
but what's a general solution for lists that will perform better than
O(n)? (i 'm assuming that's the reason why
last, nth, and get were rejected when I tried them out as candidate
solutions??)
thanks for any help!
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Re: last and nth are bad?
I'm fairly new too, but I'll take a stab. I think the koan's for 19-21 are trying to make you do exactly what you are doing: consider the performance characteristics for various operations on a vector vs a list or sequence. Problem 19, for example, is highlighting that 1 - Last is slow for a vector. The last function is really meant to operate on sequences, and therefore is restricted to only being able to use first/next in its implementation, so for a vector, it has to walk the entire vector to get to the end. 2 - Vectors can efficiently get the last value with peek. So, for 19, it seems to make sense to convert to a vector and just peek: #(peek (vec %)) For 21, the same is true: nth is a sequence operation and therefore must walk the vector. The solution here is actually what you tried (use get), but you'd need to convert the lists to a vector first: #(get (vec %) %2) So, my lesson learned here is: If you need random access or, mostly need access to the end of a fixed-length (ie non-infinite), use, or convert to a vector. But, again I'm new too :) On Thu, Jun 9, 2011 at 8:50 PM, clojurefanxx neuzhou...@gmail.com wrote: i'm a newbie working thru 4clojure.com's problems #19 thru #21 where i'm asked to write a function, which when given a list or vector, returns the last, penultimate, or an arbitrary nth element, respectively. for problem #19 (return last element), using the function last was not accepted as a good solution for both lists and vectors, but the following was accepted: user= (#(nth % (- (count %) 1)) '(5 4 3)) 3 user= (#(nth % (- (count %) 1)) '[1 2 3 4 5]) 5 for problem #21, (return arbitrary element) , using the function nth or get was not accepted. - Write a function which returns the Nth element from a sequence. (= (__ '(4 5 6 7) 2) 6) (= (__ [:a :b :c] 0) :a) (= (__ [1 2 3 4] 1) 2) (= (__ '([1 2] [3 4] [5 6]) 2) [5 6]) i think using the nth or get functions on vectors to return an element at index position n should be fine performance-wise, but what's a general solution for lists that will perform better than O(n)? (i 'm assuming that's the reason why last, nth, and get were rejected when I tried them out as candidate solutions??) thanks for any help! -- 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 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
Re: library or namespace doc helper function from repl?
You could also try (find-doc libname) On Thu, Jun 2, 2011 at 11:15 AM, Alex Robbins alexander.j.robb...@gmail.com wrote: (ns-publics 'namespace) will show all the publicly defined things in a namespace. On Thu, Jun 2, 2011 at 11:51 AM, Avram aav...@me.com wrote: Apologies for a silly question, there must be a simple way to do this from the repl, but I can't seem to find it… Is there a way from the repl to view all available functions in the library or namespace? It often happens that I know a library contains functionality I seek, but I don't yet know the name. I realize that I can try to use the Atlas url (which is awesome) or an IDE or check github, but it would be really nice not to have to leave the repl. In R I would do: library(help=libname) Thanks in advance, Avram -- 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 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 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
