How to quickly initialise an associative table in Lua?
The correct way to write this is either local t = { foo = 1, bar = 2} Or, if the keys in your table are not legal identifiers: local t = { [“one key”] = 1, [“another key”] = 2}
lua-table
lua: retrieve list of keys in a table
local keyset={} local n=0 for k,v in pairs(tab) do n=n+1 keyset[n]=k end Note that you cannot guarantee any order in keyset. If you want the keys in sorted order, then sort keyset with table.sort(keyset).
Concatenation of tables in Lua
Overcomplicated answers much? Here is my implementation: function TableConcat(t1,t2) for i=1,#t2 do t1[#t1+1] = t2[i] end return t1 end
How do you copy a Lua table by value?
Table copy has many potential definitions. It depends on whether you want simple or deep copy, whether you want to copy, share or ignore metatables, etc. There is no single implementation that could satisfy everybody. One approach is to simply create a new table and duplicate all key/value pairs: function table.shallow_copy(t) local t2 = {} … Read more
Search for an item in a Lua list
You could use something like a set from Programming in Lua: function Set (list) local set = {} for _, l in ipairs(list) do set[l] = true end return set end Then you could put your list in the Set and test for membership: local items = Set { “apple”, “orange”, “pear”, “banana” } if … Read more
How to iterate through table in Lua?
To iterate over all the key-value pairs in a table you can use pairs: for k, v in pairs(arr) do print(k, v[1], v[2], v[3]) end outputs: pears 2 p green apples 0 a red oranges 1 o orange Edit: Note that Lua doesn’t guarantee any iteration order for the associative part of the table. If … Read more
How to merge two tables overwriting the elements which are in both?
for k,v in pairs(second_table) do first_table[k] = v end
How do I append to a table in Lua
You are looking for the insert function, found in the table section of the main library. foo = {} table.insert(foo, “bar”) table.insert(foo, “baz”)
How to check if a table contains an element in Lua?
You can put the values as the table’s keys. For example: function addToSet(set, key) set[key] = true end function removeFromSet(set, key) set[key] = nil end function setContains(set, key) return set[key] ~= nil end There’s a more fully-featured example here.
How to remove a lua table entry by its key?
No, setting the key’s value to nil is the accepted way of removing an item in the hashmap portion of a table. What you’re doing is standard. However, I’d recommend not overriding table.remove() – for the array portion of a table, the default table.remove() functionality includes renumbering the indices, which your override would not do. … Read more