I have
nubi =. ({~ each"_ 1 ~.@|:@:>@((i."_ _1~) leaf~)) f.
keyi =. (i."_ _1~)@:(|:@:>@((i."_ _1~) leaf~))f.
still gives same unique indexes, just not contiguous.
(i."_ _1 ])@:(|:@:>@((i."_ _1 ]) leaf ])) i
0 1 2 0 4 2 6 2 8 6
----- Original Message -----
From: bill lam <[email protected]>
To: jprogramming <[email protected]>
Sent: Thursday, December 17, 2015 10:21 AM
Subject: [Jprogramming] nub and key of inverted table
I want an effecient method of finding nub and key of a
inverted table (rank-1 box array with equal number of
items in each cells). eg.
]i=. (,.0 2 1 0 2 1 1 1 2 1);10 2$'aaaabaaaabbabbbababb'
+-+--+
|0|aa|
|2|aa|
|1|ba|
|0|aa|
|2|ab|
|1|ba|
|1|bb|
|1|ba|
|2|ba|
|1|bb|
+-+--+
NB. nub of i
ifa ~. a=. afi i
+-+--+
|0|aa|
|2|aa|
|1|ba|
|2|ab|
|1|bb|
|2|ba|
+-+--+
NB. key of i
a i.~ ~.a
0 1 2 0 3 2 4 2 5 4
NB. definition of afi and ifa
afi
|:@:(<"_1@>)
ifa
<@(>"1)@|:
Although nub and key can be found using afi/ifa, it involves a
lot of box, I worry the time and space efficency when the table
is large. Can anyone suggest other ways to do it.
--
regards,
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