Get multidimensional list size.

ID:891677
 
Jul 26 2012, 4:39 pm
I was just experimenting a bit and wanted to see if there was a good way to get the size of a multidimensional list. This is what I came up with: Code: 
proc
    get_ListDimensions(var/list/current)
        if(!islist(current)) CRASH("Not a valid list")
        var/list/dimensions = new()
        while(islist(current))
            dimensions += length(current)
            current = current[1]
        return dimensions
The problem is, this doesn't take into account lists of lists. It only checks the first element of a each nested list which is fine if I know what I am sending it however if it was tried on a list that did not have a consistent size. (lets say a list that contained a bunch of different types of lists). It would ignore that and report the wrong info. Does anyone have a method to verify that a multidimensional list is actually a consistent multidimensional list? It would have to check every element in every nested list.
Jul 26 2012, 5:30 pm
If you need to ensure it's a true multidimensional list and not a jagged list (list of lists of varying sizes), you could always wrap it in a datum. You'll lose the ability to use operators on it, however. If it's 3-dimensions or more, it might be worth the access tradeoff for the performance (compared to recursively looping through it).

I have to ask, though, in what context are you working that you can't always control if the list will be a true multidimensional list or not?
Jul 26 2012, 5:39 pm (Edited on Jul 26 2012, 7:30 pm)
Actually, I was working on a making a datum to hold a multidimensional list in a single list (because I keep reading that BYOND is bad at multidimensional lists).

This proc was going to be used to help convert a traditional multidimensional list to the new matrix datum. If the list is a jagged list it can't be converted and I would need break out of it.

Edit: For clarity this is the islist() proc
proc/islist(list/l)
  return istype(l)
Jul 26 2012, 8:11 pm
It seems I may have found a solution although it is a bit recursion happy:

proc
  recurMatrixCheck(var/list/L)
    if(!islist(L)) return null
    var/list/c_list = new
    var/list/t_list = new
    for(var/i in L)
      if(!islist(i)) return list(L.len)
      c_list = recurMatrixCheck(i)
      if(!t_list.len) t_list = c_list
      else if(!recurCompareList(t_list,c_list)) return list(L.len)
      t_list = c_list
    c_list.Insert(1,L.len)
    return c_list

  recurCompareList(var/list/L1,var/list/L2)
    if(L1.len!=L2.len) return 0
    for(var/i=L1.len,i>0,i--)
      if(islist(L1[i])||islist(L2[i]))
        if(!recurCompareList(L1[i],L2[i])) return 0
        else if(L1[i]!=L2[i]) return 0
    return 1


Here is a test:
client
  verb
    Test_M()
      var/list/m = new(5,5,4,6,4,2,54)
      world << list2text(recurMatrixCheck(m))
      m = list(list(list(4,5,3,2),2,3,4,5),list(5,4,3,2,1),list(1,2,3,4,5),list(2,4,5,3,2))
      world << list2text(recurMatrixCheck(m))
      m = list(list(1,2,3,4,5),list(3,4,5),list(1,2,3,4,5),list(2,4,5,3,2,4,5))
      world << list2text(recurMatrixCheck(m))

proc //Just for testing purposes
  list2text(var/list/l)
    .=""
    for(var/i in l) .+="[i] "
    return .


I am not sure I am happy with all the recursion and all the variables I am creating to test this. Anyone else have any ideas?

                       Profile results (total time)
Proc Name                  Self CPU    Total CPU    Real Time        Calls
----------------------    ---------    ---------    ---------    ---------
/proc/recurMatrixCheck        0.087        0.734        0.736         7940
/client/verb/Test_M           0.021        0.142        0.142            1
/proc/recurCompareList        0.023        0.028        0.029         4803
/proc/islist                  0.011        0.016        0.020        36540
/proc/list2text               0.000        0.000        0.000            3