(count-all str1 str2)
Thinking of operations on collections to replace iteration is productive, but alas, I'm new to it. I'm looking for a way to count the number of occurrences of each and every character in str1 that occurs in str2, so that (count-all "abc" "abracadabra") will give 8 which is the count of characters in "abacaaba". Any suggestion? Thanks! Tuba -- 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: (count-all str1 str2)
Hi, how about this: (count (filter (set "abc") "abracadabra"))? Sincerely Meikel -- 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: (count-all str1 str2)
That works well. Thank you very much! Tuba On Jul 19, 1:47 am, Meikel Brandmeyer wrote: > Hi, > > how about this: (count (filter (set "abc") "abracadabra"))? > > Sincerely > Meikel -- 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: (count-all str1 str2)
Hi,
I am a newbie to clojure.
It's appreciated if you could help me to convert following C code into clojure:
float qTR(char *s1, char *s2)
{
intp,pl,q=0,r,s1l=strlen(s1),s2l=strlen(s2);
for (p=0;p wrote:
> That works well. Thank you very much!
> Tuba
>
> On Jul 19, 1:47 am, Meikel Brandmeyer wrote:
>> Hi,
>>
>> how about this: (count (filter (set "abc") "abracadabra"))?
>>
>> Sincerely
>> Meikel
>
> --
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Re: (count-all str1 str2)
On Wed, Jul 20, 2011 at 11:04 AM, Payam Mahmoudian
wrote:
> It's appreciated if you could help me to convert following C code into
> clojure:
>
> float qTR(char *s1, char *s2)
> {
> int p,pl,q=0,r,s1l=strlen(s1),s2l=strlen(s2);
>
> for (p=0;p for (pl=1;pl<=s1l-p;pl++)
> for (r=0;r if (!memcmp(s1+p,s2+r,pl)) q += pl;
>
>
> returns1l*q)/(s1l*(s1l+1)*(s1l+2)/6.0))+((s2l*q)/(s2l*(s2l+1)*(s2l+2)/6.0)))/(s1l+s2l));
> }
>
> Actually, I have a performance issue O(n^3), so I want to know if I
> could use clojure concurrency feature in this case.
Welcome to Clojure! Ideally, you should have posted a new question
instead of replying to an existing post. It messes up threads in the
discussion, you know.
Coming to your problem, it'd be great if you explain the problem and
your proposed solution in English (or pseudo-code). It's hard for
someone to convert imperative code written in C to functional Clojure
by just looking at existing code. Approaches to solve the same problem
differ and understanding the problem instead of looking at code helps.
Besides, if the algorithm itself is O(N^3), I don't think concurrency
can help you. Parallelism might, but one can't say without (again,)
understanding the problem.
Regards,
BG
--
Baishampayan Ghose
b.ghose at gmail.com
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Re: (count-all str1 str2)
On Wed, Jul 20, 2011 at 7:32 AM, Baishampayan Ghose wrote:
> On Wed, Jul 20, 2011 at 11:04 AM, Payam Mahmoudian
> wrote:
>> It's appreciated if you could help me to convert following C code into
>> clojure:
>>
>> float qTR(char *s1, char *s2)
>> {
>> int p,pl,q=0,r,s1l=strlen(s1),s2l=strlen(s2);
>>
>> for (p=0;p> for (pl=1;pl<=s1l-p;pl++)
>> for (r=0;r> if (!memcmp(s1+p,s2+r,pl)) q += pl;
>>
>>
>> returns1l*q)/(s1l*(s1l+1)*(s1l+2)/6.0))+((s2l*q)/(s2l*(s2l+1)*(s2l+2)/6.0)))/(s1l+s2l));
>> }
>>
>> Actually, I have a performance issue O(n^3), so I want to know if I
>> could use clojure concurrency feature in this case.
>
> Welcome to Clojure! Ideally, you should have posted a new question
> instead of replying to an existing post. It messes up threads in the
> discussion, you know.
>
> Coming to your problem, it'd be great if you explain the problem and
> your proposed solution in English (or pseudo-code). It's hard for
> someone to convert imperative code written in C to functional Clojure
> by just looking at existing code.
At a glance, I can tell you that it's seeing if two strings s1 and s2
have any substring in common -- for example "zoboomafoo" and "foobar"
contain a common substring "foo". For each possible substring position
as indicated by an offset into each string and a length at least 1 and
not enough to run off the end of either string, it adds the length to
a running total q if the corresponding substrings *differ*. So q ends
up smaller the more and larger common substrings turn up.
After that, it does some complicated math with the strings' lengths and q. :)
The OP may want to read up in the Knuth-Morris-Pratt algorithm to
discover the substrings more efficiently. Then q can be computed from
what it would be if the strings had no single letter in common by
subtracting for each substring n+2(n-1)+3(n-2)+ ... + n(1) where n is
that substring's length. There's probably a more efficient way to
compute q, or even to compute the return value, though.
--
Protege: What is this seething mass of parentheses?!
Master: Your father's Lisp REPL. This is the language of a true
hacker. Not as clumsy or random as C++; a language for a more
civilized age.
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Re: (count-all str1 str2)
By the way, if I had to hazard a guess I'd say he's computing a distance of some kind between the two strings, possibly the Hamming distance, and possibly for a spellchecker or something similar. Though spellcheckers generally do their comparisons on strings small enough that O(n^3) asymptotic behavior shouldn't be a big issue ... Certainly, the return value grows with q, which grows the less the two strings have in common. That much is certain from looking at the code. -- Protege: What is this seething mass of parentheses?! Master: Your father's Lisp REPL. This is the language of a true hacker. Not as clumsy or random as C++; a language for a more civilized age. -- 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
