Yes, just change the grouping function passed to group-by:
(group-by #(vector (% "Type") (% "Subtype")) coll)
The keys in the resulting map will be two-element vectors (e.g.
["TypeA" "SubTypeA"]) so you'll need to adjust the body of the for a
bit in BG's example.
Cheers,
Dave
On Sun, Oct 16, 2011 at 5:55 AM, der <derealme.derea...@gmail.com> wrote:
> Thanks BG and all other responses for your help.
>
> I have a followup question, could the same approach be extended if I
> wanted to group-by multiple entries in the map? e.g. assuming the map
> now had Type and Subtype and I wanted to "group-by" the pair Type and
> Subtype, would the same approach work?
>
> On Oct 14, 9:45 pm, Baishampayan Ghose <b.gh...@gmail.com> wrote:
>> > I'm a Clojure newbie trying to the following simple task:
>>
>> >Givenalistofmapsof the followign format: ({"Type" "A", "Value"
>> > "5"} {"Type" "B", "Value" "4"} {"Type" "A", "Value" "7.2"} {"Type"
>> > "A", "Value" "25.4"} {"Type" "B", "Value" "2.982"})
>>
>> > I want to compute alistofmapssuch that each type appears once in
>> > thelistand the value of the type is the sum of the values, so that
>> > in the example it would be:
>>
>> > ({"Type", "A", "Value", "37.6"} {"Type", "B", "Value", "6.982"})
>>
>> > Any ideas?
>>
>> I might write it like this -
>>
>> (defn sum-by-type [coll]
>> (for [[k v] (group-by #(% "Type") coll)]
>> {"Type" k "Value" (apply + (map (comp #(Float/parseFloat %)
>> #(% "Value")) v))}))
>>
>> Regards,
>> BG
>>
>> --
>> Baishampayan Ghose
>> b.ghose at gmail.com
>
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