struct sharing same key?
I would like to create an struct with the names of differents nationalities. When people are the same nationality I would don't need to repeat again the nationality. Is there any way t0 get that. For example, I would like to write something like that: (defstruct person :nationality :first :last) (def people (struct person "english" "Jim" "Silvester" "Stephen" "Howards" "chinese" "Chiu" "Chiu")) -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: struct sharing same key?
On Mon, Jun 27, 2011 at 1:10 AM, Antonio Recio wrote:
> I would like to create an struct with the names of differents nationalities.
> When people are the same nationality I would don't need to repeat again the
> nationality. Is there any way t0 get that. For example, I would like to
> write something like that:
> (defstruct person :nationality :first :last)
> (def people (struct person "english" "Jim"
> "Silvester"
> "Stephen" "Howards"
> "chinese" "Chiu" "Chiu"))
You probably want something more like a map like this:
{:english [{:first "Jim" :last "Silvester"}
{:first "Stephen" :last "Howards"}]
:chinese [{:first "Chiu" :last "Chiu"}]}
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Re: struct sharing same key?
When I repeat : the number 3 [{:3 "father Andrew D" :3 "mother Lisa D"}] I
get an error, although I can repeat number 1 with no problem. Why?
(struct person
{:1 "english person"
[{:2 "Andrew D"
[{:3 "father Andrew D"
:3 "mother Lisa D"}]
:2 "Justin M"
[{:3 "Elisa M"}]}]
:1 "chinese person"
[{:2 "Chi chi"}]
})
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Re: struct sharing same key?
:1 and :3 are keywords, not numbers.
map literals are specified in terms of key-value pairs; for example, in {a b
c d}, a and c are keys, b and d are values. In your person struct, :1 is
only used as a key once, which is why that works. This might help make
things clearer:
(struct person
{:1
"english person"
[{:2 "Andrew D"
[{:3 "father Andrew D"
:3 "mother Lisa D"}]
:2 "Justin M"
[{:3 "Elisa M"}]}]
:1
"chinese person"
[{:2 "Chi chi"}]
})
In the first pair, :1 is the key, "english person" is the value. In the
second pair, the nested vector/map thing is the key, :1 is the value. In
the last pair, "chinese person" is the key, the vector containing a map is
the value.
With all due respect, the questions you've posted to the list contain some
misunderstandings about certain Clojure fundamentals. May I suggest taking
the time to work through a tutorial or book? It will make life easier going
forward. There are many good choices to pick from, but this is one of my
personal favorites:
http://java.ociweb.com/mark/clojure/article.html
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Re: struct sharing same key?
Hi,
maybe Ken's solution needs some clarification
1. Use a map, not a struct. defstruct is kinda deprecated.
2. Use a keyword (preceded by a colon) to code the nationality. A keyword
is created only once and won't consume any more memory if you use it
repeatedly. I'm not sure whether you want to save the memory or the
repeated typing.
3. Ken bundled all persons in the map by language. This may be the right
solution for you or not. But if you do so, note that the inner maps reside
in a vector (square brackets)
Maybe something like this:
;; a function returning a map representing a person
(defn make-person [nationality first last]
{:first first :last last :nationality nationality})
;; the data on which you base the creation of persons
;; This repeats the keyword for each person
(def persons-data
[[:english "Jim" "Silvester"]
[:english "Stephen" "Howards"]
[:chinese "Chiu""Chiu"]])
;; combine the fn and the data
(def persons
(into [] (map #(apply make-person %) persons-data)))
;; A second way of storing your data uses (almost) the representation
suggested by Ken:
(def persons-data-2
{:english [["Jim" "Silvester"]
["Stephen" "Howards"]]
:chinese ["Chiu""Chiu"]})
;; This can be turned into a seq of persons like this
(def persons-2
(map
(fn [natio names]; can't use #() because it doesn't nest
(map (fn [[first last]]; note the destructuring
(make-person natio first last))
names))
persons-data-2))
Hope this helps,
Stefan
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