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Lua 5.3 Reference Manual

Copyright © 2015 Lua.org, PUC-Rio. Freely available under the terms of the Lua license.

Table Manipulation

This library provides generic functions for table manipulation. It provides all its functions inside the tabletable.

Remember that, whenever an operation needs the length of a table, the table must be a proper sequence or have a __len metamethod (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 list t.

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

Moves elements from table a1 to table a2. This function performs 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.

table.pack (···)

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

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; in those cases, the function erases the element list[pos].

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

table.sort (list [, comp])

Sorts 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.

Note that the comp function must define a strict partial order over the elements in the list; that is, it must be asymmetric and transitive. Otherwise, no valid sort may be possible.

The sort algorithm is not stable; that is, elements not comparable by the given order (e.g., equal elements) 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.

Last update: Fri Nov 27 18:43:18 BRST 2015