return index of a value
I have a vector of numbers [0 99 3334 53 2 5 99 2 55 63] I'd like to find the first index of a particular value. For example if the value was 99 then I want to return 1, b/c the index of 99 is 1. I can do this with a loop/recur structure comparing each value in the list to my desired value, however am wondering if there isn't a built-in for doing so?? thanks again! -- 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: return index of a value
Hi Glen,
Finding the *first* index isn't very Clojurish, what you want is to find *all*
the indexes, lazily. Then if you want the first one, just call first.
(use '[clojure.contrib.seq-utils :only (positions)])
(positions #{99} [0 99 3334 53 2 5 99 2 55 63])
- (1 6)
Cheers,
Stu
I have a vector of numbers
[0 99 3334 53 2 5 99 2 55 63]
I'd like to find the first index of a particular value. For example
if the value was 99 then I want to return 1, b/c the index of 99 is
1. I can do this with a loop/recur structure comparing each value in
the list to my desired value, however am wondering if there isn't a
built-in for doing so?? thanks again!
--
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Re: return index of a value
On Sep 27, 2010, at 9:45 AM, Glen Rubin wrote: I have a vector of numbers [0 99 3334 53 2 5 99 2 55 63] I'd like to find the first index of a particular value. For example if the value was 99 then I want to return 1, b/c the index of 99 is 1. I can do this with a loop/recur structure comparing each value in the list to my desired value, however am wondering if there isn't a built-in for doing so?? thanks again! In general, 'some' is used for linear searches. Given a vector 'v': (some #(and (= 99 (v %)) %) (range 0 (count v))) This is awkward because you're asking for the index and not the value itself. Index-based array manipulation is not often used in Clojure. -- 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: return index of a value
interesting! thx guys! On Sep 27, 10:45 am, Glen Rubin rubing...@gmail.com wrote: I have a vector of numbers [0 99 3334 53 2 5 99 2 55 63] I'd like to find the first index of a particular value. For example if the value was 99 then I want to return 1, b/c the index of 99 is 1. I can do this with a loop/recur structure comparing each value in the list to my desired value, however am wondering if there isn't a built-in for doing so?? thanks again! -- 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
