Raul is right: there's no native concept of a "dictionary" in J.
But dictionaries, as you see them used in Python & Swift, are alive and
well in J. They are employed by the J system itself for just the same
purposes as Apple does. (Xcode users: I'm referring to NSDictionary and
Property Lists (.plist)).
Here's 2 examples to play with, which should work with any J version, any
user session and in any locale:
ds=: SystemFolders_j_
du=: UserFolders_j_
$ds
12 2
But you ask what's the *recommended* way to implement a dictionary?
Python's motto is declared to be "there's only one way to do it." J's motto
ought to be "there's always one more way to do it". In this case we
implement a dictionary as a 2-column boxed array. If the J system uses it,
that's a recommendation.
Do: "inserting, removing, fetching and editing" as you do with any list.
(NB: ds is a 2-D array, or "table", i.e. is a list of lists.)
You can catenate two dictionaries like this:
dc=: ds,du
You can remove the 6th and 7th entries of ds like this:
(5 {. ds) , (7 }. ds)
or, more professionally, like this:
1 1 1 1 1 0 0 1 1 1 1 1 # ds
You can insert a new item like this:
ds , 'apps' ; '/applications'
Here's a verb to lookup a string (y) within a dictionary (x):
lookup=: 4 : '>1{ x {~ ({."1 x) i. <y'
ds lookup 'user'
/users/ianclark/j64-805-user
ds lookup 'addons'
/applications/j64-805/addons
On Wed, Apr 12, 2017 at 1:34 PM, Herbert Weissenbaeck // Privat <
[email protected]> wrote:
> Next beginner's question: What would be an efficient/fast (or the
> recommended) J way to implement a dictionary with strings as keys and
> arbitrary contents (nouns, verbs, boxes) as values, which allows inserting,
> removing, fetching and editing?
>
> Thank you.
>
>
>
>
> Sent from my iPhone
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