list inside list

[nitin.rathod3CW9S]

I was wondering if you can help me with the list updating issue I have.

Here is the issue, I have a list of four values that look like below.

[0] ("list1" ( "1"  "2" ))

[1] ("list2" ( "11"  "12" ))

[2] ("list3" ( "21"  "22" ))

[3] ("list4" ( "31"  "32" ))

I want to add the value "13" to "List2" so that the output looks like the list below.

[0] ("list1" ( "1"  "2" ))

[1] ("list2" ( "11"  "12" "13"))

[2] ("list3" ( "21"  "22" ))

[3] ("list4" ( "31"  "32" ))

If the input is to add "41" to "list5" then the output should look like the list below.

[0] ("list1" ( "1"  "2" ))

[1] ("list2" ( "11"  "12" ))

[2] ("list3" ( "21"  "22" ))

[3] ("list4" ( "31"  "32" ))

[4] ("list5" ( "41" ))

Let me know if you can help me with a sample code to do something like this.

[pbejse · Accepted solution]

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@nitin.rathod3CW9S wrote:

Let me know if you can help me with a sample code to do something like this.

---

Sample code

(setq MainList
       '(("list1" ("1" "2"))
	 ("list2" ("11" "12"))
	 ("list3" ("21" "22"))
	 ("list4" ("31" "32"))
	)
)

(Defun _BuildAndEdit (key val lst)
  (if (setq f (assoc key lst))
    (subst (list key (append (cadr f) (list val))) f lst)
    (append lst (list (list key (list val))))
  )
)

_$ MainList
(("list1" ("1" "2")) ("list2" ("11" "12")) ("list3" ("21" "22")) ("list4" ("31" "32")))

_$ (setq MainList (_BuildAndEdit "list2" "13"  MainList))
(("list1" ("1" "2")) ("list2" ("11" "12" "13")) ("list3" ("21" "22")) ("list4" ("31" "32")))

_$ (setq MainList (_BuildAndEdit "list5" "41"  MainList))
(("list1" ("1" "2")) ("list2" ("11" "12" "13")) ("list3" ("21" "22")) ("list4" ("31" "32")) ("list5" ("41")))

 HTH

[Kent1Cooper]

What are the bracketed numbers at the start of the lines?  Just for reference?  Are they variable names?  (You can use  [0]  as a variable name, but not just  0 .)

Your wording "a list of four values" suggests that the actual overall list is like this:

(("list1" ( "1"  "2" )) ("list2" ( "11"  "12" )) ("list3" ( "21"  "22" )) ("list4" ( "31"  "32" )))

in which case the bracketed numbers would be the index numbers of the "values" [i.e. sub-lists] in the overall list.  Is that right?  Is that overall list stored under a variable name?

Is [for example]  ("list1" ( "1"  "2" ))  really a list that includes a text string "list1" as its first item, along with a nested list ( "1"  "2" ) as its second item?  If the overall list above is not right, is this one stored in a variable called  [0]  ?  Your wording  ' I want to add the value "13" to "List2" '  makes it sound like maybe  list1  [without the quotation marks] is a variable name [not a text string] that contains the list  ( "1"  "2" )  as its only item.  Is that the situation?

[nitin.rathod3CW9S]

thanks a lot @pbejse . that was accurate solution I was looking for.

Moreover thanks for such a quick response. thanks again.

[nitin.rathod3CW9S]

[0], [1], [2],... represents index of the list inside list. actual list will look like below as you guessed already.

(("list1" ( "1"  "2" )) ("list2" ( "11"  "12" )) ("list3" ( "21"  "22" )) ("list4" ( "31"  "32" )))

thanks for your response @Kent1Cooper 

[pbejse]

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@nitin.rathod3CW9S wrote:

thanks a lot @pbejse . that was accurate solution I was looking for.

Moreover thanks for such a quick response. thanks again.

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Good for you, That's just one way of getting the result your looking for. its a Q&D code, you can develop it more by including conditions for sorting and some.

You are welcome @nitin.rathod3CW9S