Topic: How do I edit an item in a list with subst?

[dubb]

I'm having a bit of a misunderstanding on how this works.

Code: [Select]

(setq lst '("A" "B" "C"))
(subst '("1") '("A") lst)
Autodesk website shows an example of how it works but I'm not getting the results I need.
https://knowledge.autodesk.com/search-result/caas/CloudHelp/cloudhelp/2015/ENU/AutoCAD-AutoLISP/files/GUID-25214E69-090A-45C3-8210-6D9801255E44-htm.html
 

[Lee Mac]

For example:

Code - Auto/Visual Lisp: [Select]

1. _$ (setq lst '("A" "B" "C"))
2. ("A" "B" "C")
3. _$ (subst "1" "B" lst)
4. ("A" "1" "C")

Be aware that subst will replace all occurrences of item in a list:

Code - Auto/Visual Lisp: [Select]

1. _$ (setq lst '("A" "B" "C" "B" "C"))
2. ("A" "B" "C" "B" "C")
3. _$ (subst "1" "B" lst)
4. ("A" "1" "C" "1" "C")

[dubb]

Wow! That's it! So I missed it by treating each subst item as a list instead of a string.

For example:

Code - Auto/Visual Lisp: [Select]

1. _$ (setq lst '("A" "B" "C"))
2. ("A" "B" "C")
3. _$ (subst "1" "B" lst)
4. ("A" "1" "C")

Be aware that subst will replace all occurrences of item in a list:

Code - Auto/Visual Lisp: [Select]

1. _$ (setq lst '("A" "B" "C" "B" "C"))
2. ("A" "B" "C" "B" "C")
3. _$ (subst "1" "B" lst)
4. ("A" "1" "C" "1" "C")

[Lee Mac]

Wow! That's it! So I missed it by treating each subst item as a list instead of a string.

Indeed - though, the subst item can be a list if that is what your list contains, e.g.:

Code - Auto/Visual Lisp: [Select]

1. _$ (setq lst '(("A") ("B") ("C")))
2. (("A") ("B") ("C"))
3. _$ (subst '("1") '("B") lst)
4. (("A") ("1") ("C"))

[dubb]

Awesome! I love it. Thank you for enlightening me.

Wow! That's it! So I missed it by treating each subst item as a list instead of a string.

Indeed - though, the subst item can be a list if that is what your list contains, e.g.:

Code - Auto/Visual Lisp: [Select]

1. _$ (setq lst '(("A") ("B") ("C")))
2. (("A") ("B") ("C"))
3. _$ (subst '("1") '("B") lst)
4. (("A") ("1") ("C"))