Display elements by the number of occurrences in J

Question

Using the J language, I want to achieve a mapping of the counts of the elements of an array.

In particular, I want to enter a lowercase word with two different letters and return each pair of letters to the word along with counts of occurrences.

I need a verb that gives something like this in any J-structure that you think is appropriate:

For 'cocoa':

co 2
oc 1
oa 1

For a banana:

ba 1
an 2
na 2

For "milk":

mi 1
il 1
lk 1

For 'to':

to 1

(For single-letter words, such as 'a', the task is undefined and no attempt will be made.)

(The order is not important, since I have listed them.)

I can easily get consecutive pairs of letters in a word as a matrix or a list of fields:

   2(] ;._3)'cocoa'
co
oc
co
oa
   ]
   2(< ;._3)'cocoa'
┌──┬──┬──┬──┐
│co│oc│co│oa│
└──┴──┴──┴──┘

But I need help to go from there to mapping pairs to numbers.

~. ~: . .

NuVoc "Loopless" , /(/\. /\) - , , / , u/y , , , y.

(NB. "" , Java Python, . SO J. J .)

Answer 1

, dyadic infix (\):

   2 ]\ 'banana'
ba
an
na
an
na

, , key (/.)

   #/.~ 2 ]\ 'banana'
1 2 2

, :

   ({. ; #)/.~ 2 ]\ 'banana'
┌──┬─┐
│ba│1│
├──┼─┤
│an│2│
├──┼─┤
│na│2│
└──┴─┘

Answer 2

, . , .

 [t=. 2(< ;._3)'cocoa'
┌──┬──┬──┬──┐
│co│oc│co│oa│
└──┴──┴──┴──┘

~. (Nub),

   ~.t
┌──┬──┬──┐
│co│oc│oa│
└──┴──┴──┘

, -, , 1 - ,

   t =/ ~.t
1 0 0
0 1 0
1 0 0
0 0 1

, ,

    +/  t =/ ~.t
2 1 1

,

   <"0 +/  t =/ ~.t
┌─┬─┬─┐
│2│1│1│
└─┴─┴─┘

, , ,. (Stitch)

 (~.t) ,. <"0 +/  t =/ ~.t
┌──┬─┐
│co│2│
├──┼─┤
│oc│1│
├──┼─┤
│oa│1│
└──┴─┘
       [t=. 2(< ;._3)'banana'
┌──┬──┬──┬──┬──┐
│ba│an│na│an│na│
└──┴──┴──┴──┴──┘
   (~.t) ,. <"0 +/  t =/ ~.t
┌──┬─┐
│ba│1│
├──┼─┤
│an│2│
├──┼─┤
│na│2│
└──┴─┘
   [t=. 2(< ;._3)'milk'
┌──┬──┬──┐
│mi│il│lk│
└──┴──┴──┘
   (~.t) ,. <"0 +/  t =/ ~.t
┌──┬─┐
│mi│1│
├──┼─┤
│il│1│
├──┼─┤
│lk│1│
└──┴─┘

, .