Replacing an item in a list with another

Bill
I did make a mistake in the call to my code. Sorry.
Here are the corrected times.

Elapsed time: 0.041000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

Command:
Command: timer
Elapsed time: 0.030000 seconds

 

Maybe mine just looks cooler then.

Try timing this version (which I was going to post if it was what Dan wanted.

;;12/15/04 Bill Zondlo
;;Program to merge like items from one assoc list to another.
;;l1, l2 = assoc lists of matched length and items to swap.
;;Aitm = assoc item number to replace. i.e.
;; lst1 = ((1 . "") (2 . "K") (1 . "") (5 . "ff") (1 . ""))
;; lst2 = ((1 . "A") (2 . "Not This") (1 . "Door") (5 . "Or This") (1 . "all internal doors"))
;;(swaplists lst1 lst2 1) will return ((1 . "A") (2 . "K") (1 . "Door") (5 . "ff") (1 . "all internal doors"))
;;
(defun SwapLists (l1 l2 Aitm)
(apply
'append
(mapcar
'(lambda (a b)(if (= (car a) Aitm)(subst b a (list a))(list a))
)
l1 l2)
)
) ;end defun

Bill

 

Bill here is your code example:

lst new))


CAB2k,
Where did Bill post that example?
I can't find it in earlier in this thread.

The only thing I can find that he posted was:

Which doesn't make any sense whatsoever in solving the problem.

 

Here you go.

Command: timer
Elapsed time: 0.041000 seconds

Command:
Command: timer
Elapsed time: 0.050000 seconds

Command:
Command: timer
Elapsed time: 0.040000 seconds

Command:
Command: timer
Elapsed time: 0.050000 seconds

Command:
Command: timer
Elapsed time: 0.050000 seconds

Command:
Command: timer
Elapsed time: 0.051000 seconds

Command:
Command: timer
Elapsed time: 0.041000 seconds

Command:
Command: timer
Elapsed time: 0.051000 seconds

 

Well you got me.

I guess the mapcar thing evaluates each item from each list where the foreach only does one.
I think the real difference is the append at the end that takes the time. Ant the fact that I "list" each item. I'll have to work with it some more.
Still looks cooler.

Thanks

Bill

 

Bill,
That would require both lists to have a 1 for 1 mapping as to
number of elements. It also seems far from efficient. Instead
consider this

(defun SwapLists (l1 l2 Aitm)
(mapcar
'(lambda (a b)(if (= (car a) Aitm) b a)
)
l1 l2)
) ;end defun

Which should do the same as yours but without all the clutter.
Does yours do something else that I can't see?

 

Wow. That is wild. The post I see ends with

Very strange. Anne is something going on?

 

2 or 3 post after that one.
Quote
Reply From: BillZ
Date: Dec/15/04 - 06:56 (EST)

Re: Replacing an item in a list with another
Danv,
Sorry i missed your reply.
If the answer is yes then how would I do it?<<<

It would depend on the structure of the 2 lists.

Are they the same length?
Are the assoc 1's in the same order and the same quantity in each list.

A sample of each list would be most helpful.

If the lists are the same length and the assoc 1's are located in the same location in each list then:

Command: (setq lt1 '((1 . "")(2 . "K")(1 . "")(5 . "ff")(1 . "")))
((1 . "") (2 . "K") (1 . "") (5 . "ff") (1 . ""))

Command: (setq lt2 '((1 . "A")(2 . "Not This")(1 . "Door")(5 . "OR This")(1 .
"all internal doors")))
((1 . "A") (2 . "Not This") (1 . "Door") (5 . "OR This") (1 . "all internal
doors"))

Command: (setq lt3 (apply 'append (mapcar '(lambda (a b)(if (= (car a) 1)(subst
b a (list a))(list a))) lt1 lt2)))
((1 . "A") (2 . "K") (1 . "Door") (5 . "ff") (1 . "all internal doors"))

Bill

 

Definitely looks cooler.

I love the brevity of it too. I can take the mapcar lambda apart now but
still have trouble building them.

 

Doug,
Maybe you need to reload that post as I had edited it once.


Bill

 

Hi Bill,

I unsubscribed from the newsgroup and redownloaded all the
posts before I mentioned that I couldn't see your second code
solution. I don't think it exists any longer, unless it is as an
attachment that is only accessible on the web side. Strange.

In any case, Mapcar is a good approach if the lists can be
mapped. ;-)

Regards,
Doug
Using OE

 

Doug,
Once again your expertise has once again triumphed.

I would have gotten it eventually.

Thanks

Bill

 

I had to run this now 5000 times just to get a reading.

Elapsed time: 0.015000 seconds

Woo Woooo

Bill

 

Oh yeah,

And thanks for the time.

I hope it keeps me out of trouble from now on.

Bill

 

Oh yeah,

And thanks for the timer.

I hope it keeps me out of trouble from now on.

Bill

 

Thanks Bill and CAB2k for your efforts. I will take a look at both codes.

 

You're welcome,

Just in case you get lost in the thread, it's Doug Broad that gleaned the best one.

(defun SwapLists (l1 l2 Aitm)
(mapcar
'(lambda (a b)(if (= (car a) Aitm) b a)
)
l1 l2)
) ;end defun


Bill