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Table Manipulation

This library provides generic functions for table manipulation. It provides all its functions inside the table [table]{#pdf-table}.

Remember that, whenever an operation needs the length of a table, all caveats about the length operator apply (see The Length Operator). All functions ignore non-numeric keys in the tables given as arguments.

table.concat (list [, sep [, i [, j]]])

Given a list where all elements are strings or numbers, returns the string list[i]..sep..list[i+1] ··· sep..list[j]. The default value for sep is the empty string, the default for i is 1, and the default for j is #list. If i is greater than j, returns the empty string.

table.insert (list, [pos,] value)

Inserts element value at position pos in list, shifting up the elements list[pos], list[pos+1], ···, list[#list]. The default value for pos is #list+1, so that a call table.insert(t,x) inserts x at the end of the list t.

table.move (a1, f, e, t [,a2])

Moves elements from the table a1 to the table a2, performing the equivalent to the following multiple assignment: a2[t],··· = a1[f],···,a1[e]. The default for a2 is a1. The destination range can overlap with the source range. The number of elements to be moved must fit in a Lua integer.

Returns the destination table a2.

table.pack (···)

Returns a new table with all arguments stored into keys 1, 2, etc. and with a field "n" with the total number of arguments. Note that the resulting table may not be a sequence, if some arguments are nil.

table.remove (list [, pos])

Removes from list the element at position pos, returning the value of the removed element. When pos is an integer between 1 and #list, it shifts down the elements list[pos+1], list[pos+2], ···, list[#list] and erases element list[#list]; The index pos can also be 0 when #list is 0, or #list + 1.

The default value for pos is #list, so that a call table.remove(l) removes the last element of the list l.

table.sort (list [, comp])

Sorts the list elements in a given order, in-place, from list[1] to list[#list]. If comp is given, then it must be a function that receives two list elements and returns true when the first element must come before the second in the final order, so that, after the sort, i <= j implies not comp(list[j],list[i]). If comp is not given, then the standard Lua operator < is used instead.

The comp function must define a consistent order; more formally, the function must define a strict weak order. (A weak order is similar to a total order, but it can equate different elements for comparison purposes.)

The sort algorithm is not stable: Different elements considered equal by the given order may have their relative positions changed by the sort.

table.unpack (list [, i [, j]])

Returns the elements from the given list. This function is equivalent to

     return list[i], list[i+1], ···, list[j]

By default, i is 1 and j is #list.