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. <[email protected]
> <javascript:>> 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. <[email protected]>
> 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. <[email protected]>
> 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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