Re: How to generate a hash map from a list
> (defn fzipmap [f col]
> "Takes a col, applies f to each element and generates a
Note that the args should have come after the doc string!
On Tue, Aug 25, 2009 at 6:20 AM, Adrian
Cuthbertson wrote:
> For completeness we should include a loop/recur pattern;
>
> (defn fzipmap [f col]
> "Takes a col, applies f to each element and generates a
> hash map keyed on each element of col."
> (loop [col (seq col) mp {}]
> (if col (recur (next col) (assoc mp (first col) (f (first col
> mp)))
>
> user=> (fzipmap #(+ % 3) [1 2 3])
> {3 6, 2 5, 1 4}
>
> Regards, Adrian.
>
> On Mon, Aug 24, 2009 at 6:43 PM, samppi wrote:
>>
>> Wonderful; I totally didn't know about zipmap. I've been using into
>> and map this whole time. Was it added right before Clojure 1.0? It
>> seems to be a lot faster than using into:
>>
>> Clojure 1.0.0-
>> user=> (time (into {} (for [i [1 2 3]] [i (+ 3 i)])) )
>> "Elapsed time: 0.705 msecs"
>> {3 6, 2 5, 1 4}
>> user=> (time (zipmap [1 2 3] (map #(+ 3 %) [1 2 3])))
>> "Elapsed time: 0.25 msecs"
>> {3 6, 2 5, 1 4}
>>
>> On Aug 24, 9:15 am, Dragan Djuric wrote:
>>> (zipmap coll1 coll2) should be faster than (apply hash-map (interleave
>>> coll1 coll2)) and the doc description hints that's what it was made
>>> for.
>>>
>>> On Aug 24, 8:25 am, Garth Sheldon-Coulson wrote:
>>>
>>>
>>>
>>> > Welcome again.
>>>
>>> > Here's another way. Not sure if it's any more or less efficient, but it's
>>> > the way my brain works.
>>>
>>> > => (defn map-hashmap [coll f]
>>> > (apply hash-map (interleave coll (map f coll
>>> > #'user/map-hashmap
>>>
>>> > => (map-hashmap [1 2 3] #(+ % 3))
>>> > {1 4, 2 5, 3 6}
>>>
>>> > On Mon, Aug 24, 2009 at 2:18 AM, Stephen C. Gilardi
>>> > wrote:
>>>
>>> > > On Aug 23, 2009, at 8:21 PM, Stan Dyck wrote:
>>>
>>> > > I'm still new to this so bear with me.
>>>
>>> > > Welcome.
>>>
>>> > > I'm trying to apply a function to a seq-able thing to produce a
>>> > > hashmap.
>>> > >> So for instance say the function is (inc 3).
>>> > >> I'd like to write a function that does
>>>
>>> > >> [1 2 3] --> {1 4, 2 5, 3 6}
>>>
>>> > >> Can someone help me?
>>>
>>> > > Here's one way:
>>>
>>> > > user=> (into {} (for [i [1 2 3]] [i (+ 3 i)]))
>>> > > {1 4, 2 5, 3 6}
>>>
>>> > > --Steve
>> >>
>>
>
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Re: How to generate a hash map from a list
For completeness we should include a loop/recur pattern;
(defn fzipmap [f col]
"Takes a col, applies f to each element and generates a
hash map keyed on each element of col."
(loop [col (seq col) mp {}]
(if col (recur (next col) (assoc mp (first col) (f (first col
mp)))
user=> (fzipmap #(+ % 3) [1 2 3])
{3 6, 2 5, 1 4}
Regards, Adrian.
On Mon, Aug 24, 2009 at 6:43 PM, samppi wrote:
>
> Wonderful; I totally didn't know about zipmap. I've been using into
> and map this whole time. Was it added right before Clojure 1.0? It
> seems to be a lot faster than using into:
>
> Clojure 1.0.0-
> user=> (time (into {} (for [i [1 2 3]] [i (+ 3 i)])) )
> "Elapsed time: 0.705 msecs"
> {3 6, 2 5, 1 4}
> user=> (time (zipmap [1 2 3] (map #(+ 3 %) [1 2 3])))
> "Elapsed time: 0.25 msecs"
> {3 6, 2 5, 1 4}
>
> On Aug 24, 9:15 am, Dragan Djuric wrote:
>> (zipmap coll1 coll2) should be faster than (apply hash-map (interleave
>> coll1 coll2)) and the doc description hints that's what it was made
>> for.
>>
>> On Aug 24, 8:25 am, Garth Sheldon-Coulson wrote:
>>
>>
>>
>> > Welcome again.
>>
>> > Here's another way. Not sure if it's any more or less efficient, but it's
>> > the way my brain works.
>>
>> > => (defn map-hashmap [coll f]
>> > (apply hash-map (interleave coll (map f coll
>> > #'user/map-hashmap
>>
>> > => (map-hashmap [1 2 3] #(+ % 3))
>> > {1 4, 2 5, 3 6}
>>
>> > On Mon, Aug 24, 2009 at 2:18 AM, Stephen C. Gilardi
>> > wrote:
>>
>> > > On Aug 23, 2009, at 8:21 PM, Stan Dyck wrote:
>>
>> > > I'm still new to this so bear with me.
>>
>> > > Welcome.
>>
>> > > I'm trying to apply a function to a seq-able thing to produce a hashmap.
>> > >> So for instance say the function is (inc 3).
>> > >> I'd like to write a function that does
>>
>> > >> [1 2 3] --> {1 4, 2 5, 3 6}
>>
>> > >> Can someone help me?
>>
>> > > Here's one way:
>>
>> > > user=> (into {} (for [i [1 2 3]] [i (+ 3 i)]))
>> > > {1 4, 2 5, 3 6}
>>
>> > > --Steve
> >
>
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Re: How to generate a hash map from a list
Wonderful; I totally didn't know about zipmap. I've been using into
and map this whole time. Was it added right before Clojure 1.0? It
seems to be a lot faster than using into:
Clojure 1.0.0-
user=> (time (into {} (for [i [1 2 3]] [i (+ 3 i)])) )
"Elapsed time: 0.705 msecs"
{3 6, 2 5, 1 4}
user=> (time (zipmap [1 2 3] (map #(+ 3 %) [1 2 3])))
"Elapsed time: 0.25 msecs"
{3 6, 2 5, 1 4}
On Aug 24, 9:15 am, Dragan Djuric wrote:
> (zipmap coll1 coll2) should be faster than (apply hash-map (interleave
> coll1 coll2)) and the doc description hints that's what it was made
> for.
>
> On Aug 24, 8:25 am, Garth Sheldon-Coulson wrote:
>
>
>
> > Welcome again.
>
> > Here's another way. Not sure if it's any more or less efficient, but it's
> > the way my brain works.
>
> > => (defn map-hashmap [coll f]
> > (apply hash-map (interleave coll (map f coll
> > #'user/map-hashmap
>
> > => (map-hashmap [1 2 3] #(+ % 3))
> > {1 4, 2 5, 3 6}
>
> > On Mon, Aug 24, 2009 at 2:18 AM, Stephen C. Gilardi wrote:
>
> > > On Aug 23, 2009, at 8:21 PM, Stan Dyck wrote:
>
> > > I'm still new to this so bear with me.
>
> > > Welcome.
>
> > > I'm trying to apply a function to a seq-able thing to produce a hashmap.
> > >> So for instance say the function is (inc 3).
> > >> I'd like to write a function that does
>
> > >> [1 2 3] --> {1 4, 2 5, 3 6}
>
> > >> Can someone help me?
>
> > > Here's one way:
>
> > > user=> (into {} (for [i [1 2 3]] [i (+ 3 i)]))
> > > {1 4, 2 5, 3 6}
>
> > > --Steve
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Re: How to generate a hash map from a list
(zipmap coll1 coll2) should be faster than (apply hash-map (interleave
coll1 coll2)) and the doc description hints that's what it was made
for.
On Aug 24, 8:25 am, Garth Sheldon-Coulson wrote:
> Welcome again.
>
> Here's another way. Not sure if it's any more or less efficient, but it's
> the way my brain works.
>
> => (defn map-hashmap [coll f]
> (apply hash-map (interleave coll (map f coll
> #'user/map-hashmap
>
> => (map-hashmap [1 2 3] #(+ % 3))
> {1 4, 2 5, 3 6}
>
> On Mon, Aug 24, 2009 at 2:18 AM, Stephen C. Gilardi wrote:
>
>
>
> > On Aug 23, 2009, at 8:21 PM, Stan Dyck wrote:
>
> > I'm still new to this so bear with me.
>
> > Welcome.
>
> > I'm trying to apply a function to a seq-able thing to produce a hashmap.
> >> So for instance say the function is (inc 3).
> >> I'd like to write a function that does
>
> >> [1 2 3] --> {1 4, 2 5, 3 6}
>
> >> Can someone help me?
>
> > Here's one way:
>
> > user=> (into {} (for [i [1 2 3]] [i (+ 3 i)]))
> > {1 4, 2 5, 3 6}
>
> > --Steve
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Re: How to generate a hash map from a list
On Aug 23, 5:21 pm, Stan Dyck wrote:
> I'm still new to this so bear with me.
>
> I'm trying to apply a function to a seq-able thing to produce a hashmap. So
> for instance say the function is (inc 3).
> I'd like to write a function that does
>
> [1 2 3] --> {1 4, 2 5, 3 6}
>
> Can someone help me?
>
> StanD.
There may be a cleaner solution, but this works:
(defn build-map [s fun]
(apply hash-map (interleave s (map fun s
=> (build-map [1 2 3] inc)
{1 2, 2 3, 3 4}
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Re: How to generate a hash map from a list
Welcome again.
Here's another way. Not sure if it's any more or less efficient, but it's
the way my brain works.
=> (defn map-hashmap [coll f]
(apply hash-map (interleave coll (map f coll
#'user/map-hashmap
=> (map-hashmap [1 2 3] #(+ % 3))
{1 4, 2 5, 3 6}
On Mon, Aug 24, 2009 at 2:18 AM, Stephen C. Gilardi wrote:
>
> On Aug 23, 2009, at 8:21 PM, Stan Dyck wrote:
>
> I'm still new to this so bear with me.
>>
>
> Welcome.
>
> I'm trying to apply a function to a seq-able thing to produce a hashmap.
>> So for instance say the function is (inc 3).
>> I'd like to write a function that does
>>
>> [1 2 3] --> {1 4, 2 5, 3 6}
>>
>> Can someone help me?
>>
>
> Here's one way:
>
> user=> (into {} (for [i [1 2 3]] [i (+ 3 i)]))
> {1 4, 2 5, 3 6}
>
> --Steve
>
>
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Re: How to generate a hash map from a list
(def a [1 2 3])
; zipmap takes two collections and makes a hash-map
user=> (zipmap a (map #(+ 3 %) a))
{3 6, 2 5, 1 4}
; another way is to build up a map starting with empty {} and
associating key values
user=> (reduce #(assoc %1 %2 (+ 3 %2)) {} a)
{3 6, 2 5, 1 4}
; hash-map constructs a map for a list of values (use flatten from
contrib/seq-utils to be more concise)
user=> (apply hash-map (filter (complement sequential?) (rest (tree-
seq sequential? seq (for [i a] [i (+ 3 i)])
{1 4, 2 5, 3 6}
; into constructs a hashmap from a sequence of key/value pairs
; which is convenient to use with the for list comprehension
user=> (into {} (for [i a] [i (+ 3 i)]))
{3 6, 2 5, 1 4}
Regards,
Tim
On Aug 24, 10:21 am, Stan Dyck wrote:
> I'm still new to this so bear with me.
>
> I'm trying to apply a function to a seq-able thing to produce a hashmap. So
> for instance say the function is (inc 3).
> I'd like to write a function that does
>
> [1 2 3] --> {1 4, 2 5, 3 6}
>
> Can someone help me?
>
> StanD.
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Re: How to generate a hash map from a list
On Aug 23, 2009, at 8:21 PM, Stan Dyck wrote:
I'm still new to this so bear with me.
Welcome.
I'm trying to apply a function to a seq-able thing to produce a
hashmap. So for instance say the function is (inc 3).
I'd like to write a function that does
[1 2 3] --> {1 4, 2 5, 3 6}
Can someone help me?
Here's one way:
user=> (into {} (for [i [1 2 3]] [i (+ 3 i)]))
{1 4, 2 5, 3 6}
--Steve
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