Lua - Tables and the table library.

Lua module U105

Tables and the table library.

Exercises, examples and other material relating to training module U105. This topic is presented on public courses Learning to program in Lua, Lua Programming, Lua Programming

Articles and tips on this subject		updated
4571	Lua - using modules to add your own utilities Lua is a small language ... but that doesn't mean it lacks capabiities - it just means that you need to write some code yourself to implement simple utilities that you would cherry pick from huge libraries in other languages. For example from this week's course, I've written functions to split a line ...	2015-11-05
4273	Dot or Colon separator between table name and member in Lua - what is the difference? When do I use a dot and when do I use a colon in referencing a table member in Lua? It's a good question and one that we answer (and demonstrate to help make clear) on our Lua Programming Course. Dot refers to a table member. So if I write source.read() I am saying "run the read function ...	2014-05-06
4248	Metatables, Metamethods, classes and objects in Lua In Lua, almost everything (!) is held as a table. You don't have lists, hashes, dicts, arrays, objects, namespaces - you have tables. It helps consistency, in helps keep the language small - but at times it does mean you have to be a little bit more aware of how the features of tables can be combined ...	2014-03-20
3725	Lua Tables Lua's Tables are its "collection" variables - in other words, they hold a whole series of other variables, which can be looked up by a key of some sort. I can set up a table like this: occupancy = {2,5,5,3,2} which will set up a Lua variable called "occupancy" with five members, numbered ...	2012-05-12 (longer)
3694	Special __ methods you can use in Lua metatables In Lua, you can associate an additional table (known as a metatable) with each table of data and code you have. By doing so, repeated values and functions that apply across as whole series ("type", "class") of tables only have to be defined once. A very neat way for Lua to provide the OO facilities ...	2012-04-12
2703	Lua Metatables In a recent article ([here]), I asked if Lua was an object oriented language - and I concluded that it supports the OO paradigm very well, even though it doesn't have keywords like "class", "private" or "extends". At the end of that article, I mentioned metatables - a subject I have carefully sidestepped ...	2010-04-02
2699	Lua tables - they are everything In PHP, it sometimes feels like the answer to every question is "there's a function to do that" and in Lua, it seems the answer is always "it's a table" or "use a table"! I'm running a Lua course this week, and I have just posted up an example in which I set up a table and showed some of the flexibilities ...	2010-03-31
2499	ourdog is Greyhound, Staffie and Ginger Cake It was the fact that the cake wrapper was on the bed, and not on the bedside table that was the clue that triggered me to realizing that something wasn't quite where I had left it. And examining the wrapper and finding it empty and clear, I realised that something else - the remaining slice of cake ...	2009-11-10
2346	The indexed and hashed parts of a Lua table A Lua table contains both a sequentially indexed section and a hash keyed section (and a few other things too). When you sort the table, you sort only the index keyed section, when you use ipairs you use just the first (indexed) section, but when you use pairs you use the whole table. See source code ...	2009-08-12
1742	Lua - Table elements v table as a whole Lua ... If you refer to a table name WITHOUT square brackets, you are referring to (and will effect) the whole table ... but if you refer to a table name and put something thereafter in square brackets, you are referring to just one element of the table. Actually, an almost identical story applies to ...	2008-08-07
1697	Sorting in lua - specifying your own sort routine In Lua, the table.sort function allows you to sort a table and by default is sorts into the order that's given back by the < operator on each of the objects to be sorted. If you want to override this behaviour, you can pass the name of a function into Lua's sort and it will call this function each ...	2008-07-05

Examples from our training material

asort	Sorting an Associative table
cleversort	Sorting with a user defined routine
clo_demo	User defined sorting in Lua
clone	Duplicate (clone) a table
duh	What is in a table?
imex	implode in Lua
moretab	Getting the minimum number from a table
ooco	Assignment of a table - by reference
party	Read and store data until we get a blank line
ph	pairs, ipairs and #tablename iteration
settab	Set up a table, output in reverse
sf3	Read file, split line, tables of tables
sorting	Sorting tables
spjo	Split and Join a string into / from a table
synsug	. v ["...."] v insert
t1	mixing associative and normal in table
taba	Tables as associative arrays
tabo	Tables - some basics
tat	whole table v single member, pairs v ipairs
tinies	Reading a file and creating a table

Background information

Some modules are available for download as a sample of our material or under an Open Training Notes License for free download from [here].

Topics covered in this module

Introduction.
Tables as arrays.
Table equality and copying.
Sort, Concatanate, remove and others.
Table Traversal Functions.
Building other structures from tables.

Complete learning

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