Now that I think about it, I wonder why your categories aren't keyed by id,
like this:
(def categories [ {1 {:text "foo"} 2 {:text "bar" :ack 5}} {3 {:age 7}}])
Then the update-in can take the category id, instead of having to know its
index within a vector:
(update-in categories [1 3] merge { :age 12 :somethingElse 29 })
[{1 {:text "foo"}, 2 {:text "bar", :ack 5}} {3 {:age 12, :somethingElse
29}}]
On Monday, January 26, 2015 at 9:42:56 AM UTC-6, Michael Willis wrote:
>
> (def categories [ [ { :id 1 :text "foo" } { :id 2 :text "bar" :ack 5 } ] [
> { :id 3 :age 7 } ] ])
> #'user/categories
> (update-in categories [1 0] merge { :age 12 :somethingElse 29 })
> [[{:text "foo", :id 1} {:text "bar", :ack 5, :id 2}] [{:age 12,
> :somethingElse 29, :id 3}]]
>
>
> On Monday, January 26, 2015 at 8:54:58 AM UTC-6, Erik Price wrote:
>>
>> Many functions that affect keyed collections will work on vectors if you
>> supply the numeric index as a key.
>>
>> e
>>
>> On Monday, January 26, 2015, Josh Stratton <stratto...@gmail.com> wrote:
>>
>>> I'm new to clojure and FP in general. One thing that has always been a
>>> little confusing for me is working with immutable trees. I have a vector
>>> of categories, each category containing a vector of items--each one a
>>> hashmap. In that hashmap I have a bunch of attributes including an
>>> item-id. Now, assuming I have an item id, what's the easiest way to update
>>> the appropriate hashmap? I can't use an assoc, I believe, because my data
>>> is in a vector--not keyed by the id.
>>>
>>> What I have been doing is writing a function that maps the categories to
>>> new categories and then write another function that is called on every item
>>> and updates it iff the item id matches. This works, but it seems really
>>> clunky and I'm assuming there's a simpler way to do it.
>>>
>>> ; categories is a vector of item vectors, where the item is a hash
>>> (def categories [ [ { :id 1 :text "foo" } { :id 2 :text "bar" :ack 5 } ]
>>> [ { :id 3 :age 7 } ] ])
>>>
>>> Is there a more elegant workflow for updating categories? Let's say I
>>> want to update item of id 3 with { :age 12 :somethingElse 29 }, what's the
>>> easiest way to do this?
>>>
>>> ; so the return would be
>>> [ [ { :id 1 :text "foo" } { :id 2 :text "bar" :ack 5 } ] [ { :id 3 :age
>>> 12 :somethingElse 29 } ] ]
>>>
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