On Wed, Jan 25, 2012 at 10:45 AM, Simon Holgate <simon.holg...@gmail.com> wrote:
> I've retrieved some data from my database which is returned as a
> clojure.lang.PersistentVector:
> org.psmsl.netcdf.core> res
> [{:name "BREST", :time #<Date 1807-01-01>, :rlrdata 6882M} {:name
> "BREST", :time #<Date 1807-02-01>, :rlrdata 6908M} {:name
> "BREST", :time #<Date 1807-03-01>, :rlrdata 6873M}...{:name
> "BREST", :time #<Date 2008-11-01>, :rlrdata 7140M} {:name
> "BREST", :time #<Date 2008-12-01>, :rlrdata 7088M}]
> org.psmsl.netcdf.core> (class res)
> clojure.lang.PersistentVector
>
> I thought I should be able to do:
> (vals res)
> and
> org.psmsl.netcdf.core> (get res :time)
> returns nil
>
> What am I doing wrong?
>From what I can tell, you want to list the values and extract the
value associated with :time for a map. The problem is that res is not
a map, but a vector of maps. If you want to do these operations on
every map in the vector you can use the map function ("map" as in "to
map"):
(map vals res)
(map :time res)
In the last example I made use of the fact that keywords also work as
functions. (:some-keyword some-map) is the same as (get some-map
:some-keyword).
To play in the repl with the first value in the vector in the repl you
can extract it with nth or get:
user> (def res ...)
#'res
user> (def first-res (nth res 0))
#'first-res
user> (vals first-res)
...
user> (get first-res :time)
...
// raek
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