Reformatting of a list

Here is one way to do it:

list1 = list(list("a" "1" "1") list("a" "1" "2") list("a" "2" "3") list("b" "5" "5") list("b" "5" "6") list("b" "7" "8"))
tbl = makeTable("test" nil)
foreach(x list1 tbl[car(x)] = append1(tbl[car(x)] buildString(cdr(x) ",")))
list2 = tableToList(tbl)

A couple of comments about this:

1. I try to avoid "append" and "append1" as much as possible for performance reasons. The "cons" command is usually a better choice, but it adds to the front of the list. In this case, your list is short so if we know that will always be the case, this will work.

2. I prefer tables to complicated lists. Your list2 table looks like a key/value pair, so maybe you don't need the final "tableToList" command and can work with the table instead. Tables are much more efficient and in this case it is a cleaner simpler structure.

3. If what you are describing has to do with lists of points, then there are more things I would change.

I hope that helps.

Derek

Thanks Derek,

I work on it this morning and end up using the exact same code that you propose!

I never use the makeTable before, so I was not really confident using it.

3. If what you are describing has to do with lists of points, then there are more things I would change.

For my personal curiosity, what would you modify?

Thanks.

Regard.

Fred

First of all, the numbers would not be quoted strings.

Secondly, a list of coordinates is essentially a list of list-pairs. The coordinates "1,1" "1,2" "2,3" would be represented in lists like this:
list(list(1 1) list(1 2) list(2 3))

Skill allows you to simplify a coordinate list-pair with a colon, so a simpler implementation of the above is:
list(1:1 1:2 2:3)

Therefore, your table could simply be:
tbl["a"] = list(1:1 1:2 2:3)
tbl["b"] = list(5:5 5:6 7:8)

Since these are numbers, you could provide this list of points to dbCreatePolygon directly. In your string based example, you'd have to parse the data to produce usable coordinates for other Skill commands.

Derek

OK got it.

Unfortunatly my list came from a text import and do not represent coordinate pair, so I am stuck with the parsing.

Thanks for the clarification, it's greatly appriciate.

Regard.

Fred