Disclaimer, I'm only looking at how I would want to write it. You may
need to do something else if you have specific performance
requirements.
clojure.set is probably your friend.
user=> (def xrel #{{:id 1, :foo "bar"} {:id 2, :foo "car"} {:id 3, :foo "dog"}})
#'user/xrel
user=> (use 'clojure.set)
nil
user=> (select (fn [{:keys [id]}] (not= id 1)) xrel)
#{{:id 2, :foo "car"} {:id 3, :foo "dog"}}
or, if this is something you do often enough
user=> (def xrel #{{:id 1, :foo "bar"} {:id 2, :foo "car"} {:id 3, :foo "dog"}})
#'user/xrel
user=> (use 'clojure.set)
nil
user=> (require 'clojure.data)
nil
user=> (defn submap [sub super]
(->
(clojure.data/diff sub super)
last
(= sub)))
#'user/submap
user=> (select (partial (complement submap) {:id 1}) xrel)
#{{:foo "car", :id 2} {:foo "dog", :id 3}}
On Fri, Mar 23, 2012 at 2:50 AM, Philip Potter
<philip.g.pot...@gmail.com> wrote:
> Might it be possible to use a map instead? Maps are designed to look values
> up by a key which may differ from the value, which seems to be your use case
> here.
>
> If you have
>
> {1 {:id 1, :foo "bar"},
>
>
> 2 {:id 2, :foo "car"}}
>
> You can just do
>
> (disj my-map 2)
>
> To convert the original set into a map, you could do something like:
>
> (into {} (map (juxt :id identity) my-set))
>
> Phil
>
> On Mar 23, 2012 2:59 AM, "Leandro Oliveira" <lolive...@gmail.com> wrote:
>>
>> Hi all,
>>
>> I have a set of hash like this:
>>
>> #{{:id 1, :foo "bar"} {:id 2, :foo "car"}}
>>
>> and I'd like to remove an item based on its id value.
>>
>> Unfortunately, disj requires that I pass the whole map as key to remove
>> it.
>>
>> Can I remove the map from the set only using the id?
>>
>> My intention is to avoid a lookup on set to get the whole map back.
>>
>> Any suggestions?
>>
>>
>> Thanks in advance.
>> leandro.
>>
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