Hussein,
I'm not super comfortable with zippers, and probably wouldn't use them for
something like this - but I had a go.
If you define a zipper like this:
(z/zipper #(get % "children") #(get % "children") (fn [_ x ] x) {"children"
data})
Note the top-level vector is being wrapped in a map, so it resembles its
descendants. And then define this utility function:
(defn edit-parents [editable? edit loc]
(loop [loc loc]
(if (z/end? loc)
(z/root loc)
(if (editable? (z/node loc))
(recur (-> loc z/up (z/edit edit) z/up z/next))
(recur (z/next loc))))))
On Mon, Aug 24, 2015 at 10:40 AM, Hussein B. <hubaghd...@gmail.com> wrote:
> Hi Moe,
>
> I have this structure:
>
> [{"a" {"b" 1 "c" 2}
> "children" [{"a" {"b" 3 "c" 4} "children" []}]}
> {"a" {"b" 5 "c" 6} "children" []}
> {"a" {"b" 7 "c" 8}
> "children" [{"a" {"b" 9 "c" 10} "children" []} {"a" {"b" 10 "c" 10}
> "children" []}]}]
>
> That is only a sample, the actual data is bigger is properly more one or
> two nesting in the children attribute.
>
> I need to find a map by a criteria, say where b = 10 ({"a" {"b" 10 "c" 10}
> "children" []})
>
> Once it is found, I need to change its position within its parent. The
> parent is {"a" {"b" 7 "c" 8}
>
> I know that zippers are for editing data structures but I'm not sure how
> to do it.
>
> Thanks for help and time.
>
> On Friday, August 21, 2015 at 7:14:13 PM UTC+2, Moe Aboulkheir wrote:
>>
>> Hussein,
>>
>> I don't get an NPE passing that to traverse, but nothing much
>> interesting happens either. The top-level data structure (and the
>> vectors within "children") aren't associative, and so don't pass the
>> branch? test (contains? % "children").
>>
>> You could certainly extend the zipper to cover both cases, but there
>> may well be a more compact way to accomplish your goal. What do you
>> want to do with the piece of data?
>>
>> Take care,
>> Moe
>>
>> On Fri, Aug 21, 2015 at 5:57 PM, Hussein B. <hubag...@gmail.com> wrote:
>> > Here is my zipper:
>> >
>> > (z/zipper #(contains? % "children") #(get % "children") (fn [_ c] c)
>> s)
>> >
>> > On Friday, August 21, 2015 at 6:49:25 PM UTC+2, Moe Aboulkheir wrote:
>> >>
>> >> Hussein,
>> >>
>> >> How are you constructing your zipper, before passing it to traverse?
>> >> Note that clojure.zip doesn't work on arbitrary data structures
>> >> without being given some information about how to descend
>> >> into/construct nodes, etc. - i.e. z/next expects a zipper, and your
>> >> data structure isn't a zipper, but an input to a zipper. Unless
>> >> you've written a zipper you omitted from your post, zipping over maps,
>> >> in particular, may not be as convenient as you're imagining.
>> >> https://clojuredocs.org/clojure.zip/zipper has helpful examples in
>> it.
>> >>
>> >> Take care,
>> >> Moe
>> >>
>> >> On Fri, Aug 21, 2015 at 5:06 PM, Hussein B. <hubag...@gmail.com>
>> wrote:
>> >> > Hi,
>> >> >
>> >> > I changed println to z/node , this time I'm getting:
>> >> >
>> >> > NullPointerException clojure.zip/branch? (zip.clj:73)
>> >> >
>> >> > On Friday, August 21, 2015 at 5:56:10 PM UTC+2, Moe Aboulkheir
>> wrote:
>> >> >>
>> >> >> Hussein,
>> >> >>
>> >> >> The println inside (recur) will return nil.
>> >> >>
>> >> >> Take care,
>> >> >> Moe
>> >> >>
>> >> >> On Fri, Aug 21, 2015 at 4:35 PM, Hussein B. <hubag...@gmail.com>
>> wrote:
>> >> >> > Hi,
>> >> >> >
>> >> >> > I have this structure:
>> >> >> >
>> >> >> > (def s [{"n" {"id" "a"} "d" 2 "children" [{"n" {"id" "c"} "d" 4
>> >> >> > "children"
>> >> >> > []}]} {"n" {"id" "b"} "d" 3 "children" []}])
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > And I wrote a function with zippers to traverse it:
>> >> >> >
>> >> >> > (defn traverse [col]
>> >> >> > (loop [z col]
>> >> >> > (if (= (z/next z) z)
>> >> >> > z
>> >> >> > (if (z/branch? z)
>> >> >> > (recur (z/next z))
>> >> >> > (recur (-> z println z/next))))))
>> >> >> >
>> >> >> >
>> >> >> > But I'm getting: NullPointerException clojure.zip/next
>> >> >> > (zip.clj:236)
>> >> >> >
>> >> >> > Any ideas?
>> >> >> >
>> >> >> > Thanks for help.
>> >> >> >
>> >> >> > --
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