Topic: Count Items in a list

[MP]

Of all the weird ways to say "that flavor has already been written" that was the most recent I've read.

I don't recall seeing Stefan's submission before -- great minds think alike?

[Marc'Antonio Alessi]

Of all the weird ways to say "that flavor has already been written" that was the most recent I've read.

I don't recall seeing Stefan's submission before -- great minds think alike?

https://www.theswamp.org/index.php?topic=50539.msg556727#msg556727
 

[MP]

Cool beans, thanks Marc.

[Grrr1337]

Nice thread, thanks for bumping it up. Now I've remembered that gotta figure out such counter for an association lists.

Code: [Select]

(list
'("A" "B" 10)
'("A" "C" 20)
'("B" "C" 10)
'("A" "B" 10)
'("A" "C" 20)
'("A" "B" 10)
)
-->
(list
'(("A" "B" 10) . 3)
'(("A" "C" 20) . 2)
'(("B" "C" 10) . 1)
)


[MP]

It's been done. I'd search for you but I'm sick as a dawg right now.

[Grrr1337]

It's been done. I'd search for you but I'm sick as a dawg right now.

Thanks for comfirming, I feel relatively new for theswamp so I have no idea whats below the surface, expect big fishes.

[MP]

Given a couple quick and dirty functions (not hardly optimized) ...

Code: [Select]

(defun _Positions ( x lst / p )
    ;;  find all the positions of x in lst
    ;;  (_Positions 1 '(0 0 1 0 0 1)) >> (2 5)
    (if (setq p (vl-position x lst))
        (   (lambda ( lst result )
                (while (setq p (vl-position x lst))
                    (setq
                        result (cons (+ 1 p (car result)) result)
                        lst    (cdr (member x lst))
                    )
                )
                (reverse result)
            )
            (cdr (member x lst))
            (list p)
        )
    )   
)

Code: [Select]

(defun _Tally ( x lst )
    ;;  count all the occurances of x in lst
    ;;  (_Tally 1 '(0 0 1 0 0 1)) >> 2
    (length (_Positions x lst))
)

Code: [Select]

(defun _Distil ( lst / result )
    (while lst
        (setq
            result (cons (car lst) result)
            lst    (vl-remove (car result) (cdr lst))
        )
    )
    (reverse result)       
)

Code: [Select]

(defun _TallyHo ( lst )
    (mapcar
        (function (lambda (x) (cons x (_Tally x lst))))
        (_Distil lst)
    )
)
Then ...

(_TallyHo
   '(
       ("A" "B" 10)
       ("A" "C" 20)
       ("B" "C" 10)
       ("A" "B" 10)
       ("A" "C" 20)
       ("A" "B" 10)
    )
)

>>

(
   (("A" "B" 10) . 3)
   (("A" "C" 20) . 2)
   (("B" "C" 10) . 1)
)

Cheers (now where'd I'd leave that big bowl ...).

[Marc'Antonio Alessi]

Cool beans, thanks Marc.

If we can go on demential:

Code: [Select]

Benchmark.lsp | © 2005 Michael Puckett | All Rights Reserved
Length   : 160000    Positions: 16
Elapsed milliseconds / relative speed for 512 iteration(s):
    (ALE_POSITIONSD 1 ALIST).....1828 / 2.56 <fastest>
    (ALE_POSITIONSD 1 ALIST).....1844 / 2.53
    (MP_POSITIONS 1 ALIST).......4625 / 1.01
    (MP_POSITIONS 1 ALIST).......4672 / 1 <slowest>


Code: [Select]

; 20161206
(defun ALE_PositionSd (i l / n r c) ; ALE_PositionS(demential)
  (setq n -1)
  (while (setq c (vl-position i l))
    (setq l (cdr (ALE_List_NthCdr c l))  r (cons (setq n (+ 1 c n)) r))
  )
  (reverse r)
)ALE_List_NthCdr  see: https://www.theswamp.org/index.php?topic=46419.msg514475#msg514475

[Grrr1337]

Given a couple quick and dirty functions (not hardly optimized) ...
<...>
Cheers (now where'd I'd leave that big bowl ...).

This is a good start, thanks alot MP! 

[MP]

You're very welcome, thanks for the thanks, cheers.