I'd expect
(persistent!
(reduce-kv (fn [acc k v] (assoc! acc k (inc v)))
(transient {})
input-map))
to be the fastest solution.
Cheers,
Michał
On 2 February 2014 05:30, Justin Smith <noisesm...@gmail.com> wrote:
> Excellent, thanks for the information.
>
> I just did a benchmark of zipmap over keys and vals vs. into {} over a
> map, and despite my intuition, they are actually nearly identical in
> performance. So if zipmap were using transients zipmap with keys and vals
> would actually be the better performing option here.
>
> user> (def testmap (zipmap (range 1000) (range 2000 3000)))
> user> (crit/bench (zipmap (keys testmap) (map inc (vals testmap))))
> Evaluation count : 150900 in 60 samples of 2515 calls.
> Execution time mean : 401.458681 µs
> Execution time std-deviation : 4.912358 µs
> Execution time lower quantile : 393.882254 µs ( 2.5%)
> Execution time upper quantile : 409.534676 µs (97.5%)
> Overhead used : 2.203076 ns
>
> Found 1 outliers in 60 samples (1.6667 %)
> low-severe 1 (1.6667 %)
> Variance from outliers : 1.6389 % Variance is slightly inflated by
> outliers
> nil
> user> (crit/bench (into {} (map (fn [[k v]] [k (inc v)]) testmap)))
> Evaluation count : 150060 in 60 samples of 2501 calls.
> Execution time mean : 400.684810 µs
> Execution time std-deviation : 3.489015 µs
> Execution time lower quantile : 395.127605 µs ( 2.5%)
> Execution time upper quantile : 407.132405 µs (97.5%)
> Overhead used : 2.203076 ns
> nil
>
>
> On Saturday, February 1, 2014 8:22:28 PM UTC-8, Ambrose Bonnaire-Sergeant
> wrote:
>
>> It also might help to notice KeySeq defines first/next, but never
>> explicitly walks the seq.
>>
>> That's left to the user of the KeySeq.
>>
>> Thanks,
>> Ambrose
>>
>>
>> On Sun, Feb 2, 2014 at 12:18 PM, Michał Marczyk <michal....@gmail.com>wrote:
>>
>> On 2 February 2014 05:14, Justin Smith <noise...@gmail.com> wrote:
>>>
>>>> Pardon my ignorance but if this is producing a lazy result, how is it
>>>> doing so?
>>>> https://github.com/clojure/clojure/blob/dff9600387b962f16fc78e6477e10e
>>>> 34651fd366/src/jvm/clojure/lang/APersistentMap.java#L134
>>>>
>>>
>>> APersistentMap's KeySeq.create and ValSeq.create are pretty much
>>> equivalent to (map key entry-seq) and (map val entry-seq). The logic
>>> producing entry-seq lives in the individual map types and is indeed lazy.
>>>
>>> Cheers,
>>> Michał
>>>
>>>
>>>>
>>>> On Saturday, February 1, 2014 7:54:32 PM UTC-8, Ambrose
>>>> Bonnaire-Sergeant wrote:
>>>>
>>>>> zipmap could also potentially use transients (which would be a nice
>>>>> addition).
>>>>>
>>>>> keys/vals are also lazy, so I would be surprised if there was any
>>>>> performance
>>>>> difference with walking the seq "twice".
>>>>>
>>>>> Thanks,
>>>>> Ambrose
>>>>>
>>>>>
>>>>> On Sun, Feb 2, 2014 at 11:35 AM, Justin Smith <noise...@gmail.com>wrote:
>>>>>
>>>>>> Realistically, how many situations are there where running keys and
>>>>>> vals independently is preferable to running seq once and using the two
>>>>>> element vectors that returns?
>>>>>>
>>>>>> Usually this way one can avoid walking the whole thing twice.
>>>>>>
>>>>>> (into {} (map (fn [[k v]] [k (inc v)]) {:a 0 :b 1})) is
>>>>>> representative of the idiom I usually use. As a bonus, into uses
>>>>>> transients, which can create the resulting structure in fewer cycles /
>>>>>> less
>>>>>> time.
>>>>>>
>>>>>>
>>>>>> On Saturday, February 1, 2014 10:00:33 AM UTC-8, Sam Ritchie wrote:
>>>>>>
>>>>>>> Looks like Rich just chimed in with:
>>>>>>>
>>>>>>> "keys order == vals order == seq order "
>>>>>>>
>>>>>>> Matching Socks
>>>>>>> January 31, 2014 7:31 PM
>>>>>>> Actually, http://dev.clojure.org/jira/browse/CLJ-1302 "keys and
>>>>>>> vals consistency not mentioned in docstring" was declined, with the
>>>>>>> comment
>>>>>>> "The absence of this property in the docs is correct. You should not
>>>>>>> rely
>>>>>>> on this."
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Wednesday, August 11, 2010 6:03:39 PM UTC-4, Chouser wrote:
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