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method for serializing lua tables
(5 answers)
Closed 8 years ago.
I would like to serialize a table so that I can insert it into a database and retrieve it later on. How would I do this?
maybe like this https://gist.github.com/rangercyh/5814003
local szStr = ""
function print_lua_table (lua_table, indent)
indent = indent or 0
for k, v in pairs(lua_table) do
if type(k) == "string" then
k = string.format("%q", k)
end
local szSuffix = ""
if type(v) == "table" then
szSuffix = "{"
end
local szPrefix = string.rep(" ", indent)
formatting = szPrefix.."["..k.."]".." = "..szSuffix
if type(v) == "table" then
szStr = szStr..formatting
print_lua_table(v, indent + 1)
szStr = szStr..szPrefix.."},"
else
local szValue = ""
if type(v) == "string" then
szValue = string.format("%q", v)
else
szValue = tostring(v)
end
szStr = szStr..formatting..szValue..","
end
end
end
How to serialize Lua value nicely?
local serialize
do
local num_fmt = '%.17g'
local NaN_serialized = { -- This idea was stolen from lua-nucleo
[num_fmt:format(1/0)] = '1/0',
[num_fmt:format(-1/0)] = '-1/0',
[num_fmt:format(0/0)] = '0/0'
}
local function serialize_table(t, indent)
indent = indent or ''
local new_indent = indent..'\t'
if next(t) == nil then
return '{}'
else
local lines = {}
local function add_line(key)
local ser_key = key
if type(key) ~= 'string' or not key:find'^[%a_][%w_]*$' then
ser_key = '['..serialize(key, new_indent)..']'
end
table.insert(lines,
ser_key..' = '..serialize(t[key], new_indent))
end
local other_keys = {}
local keys = setmetatable({number = {}, string = {}},
{__index = function() return other_keys end})
for k in pairs(t) do
table.insert(keys[type(k)], k)
end
table.sort(keys.number)
table.sort(keys.string)
for _, k in ipairs(keys.number) do
add_line(k)
end
for _, k in ipairs(keys.string) do
add_line(k)
end
for _, k in ipairs(other_keys) do
add_line(k)
end
return '{\n'..new_indent..table.concat(lines, ',\n'..new_indent)
..'\n'..indent..'}'
end
end
function serialize(v, indent)
if type(v) == 'string' then
return ('%q'):format(v)
elseif type(v) == 'boolean' then
return tostring(v)
elseif type(v) == 'nil' then
return tostring(v)
elseif type(v) == 'number' then
return (num_fmt:format(v):gsub('^.*', NaN_serialized))
elseif type(v) == 'table' then
return serialize_table(v, indent)
else
error('Can not serialize '..type(v))
end
end
end
-- What it can:
print(serialize(math.huge))
print(serialize'"What\'s up?"\n\t123')
print(serialize{{}, {{}}})
-- And what it can not:
local t = {}
local tt = {[t] = t}
print(serialize(tt)) -- tt is not a tree, so it was serialized incorrectly
Related
I am trying to read the following stream:
127.0.0.1:6379> xrevrange driver:70 + - count 1
1) 1) "1656531417451-0"
2) 1) "field1"
2) "value1"
3) "isbusy"
4) "true"
How can I read this stream in Lua script and reflect the field isbusy from the stream into the the local Lua variable is_busy?
I could not get my head around Lua collections.
local stream = KEYS[1]
local is_busy = false
local messages = redis.call("XREVRANGE", stream, "+", "-", "COUNT", "1")
for _, message in ipairs(messages) do
end
You need to parse the nested structure:
local id
for _, message in ipairs(messages) do
for i, sub_msg in ipairs(message) do
if i == 1 then
id = sub_msg
else
-- parse attributes
local i = 1
while i < #sub_msg do
local k = sub_msg[i]
local v = sub_msg[i + 1]
if k == "isbusy" then
is_busy = v
end
i = i + 2
end
end
end
end
I'm trying to use Julia to solve the common tile game 15 Puzzle using Julia using A* algorithm. I am quite new to the language and my style may seem very C like. When I try the following code, I run out of memory. I'm not sure if its related to the use of a pointer style in my structs or just bad design.
struct Node
parent
f::Int64
board::Array{Int64,1}
end
function findblank(A::Array{Int64,1})
x = size(A,1)
for i = 1:x
if A[i] == x
return i
end
end
return -1
end
function up(A::Array{Int64,1})
N = size(A,1)
Nsq = isqrt(N)
blank = findblank(A)
B = copy(A)
if blank / Nsq <= 1
return nothing
end
B[blank-Nsq],B[blank] = B[blank],B[blank-Nsq]
return B
end
function down(A::Array{Int64,1})
N = size(A,1)
Nsq = isqrt(N)
blank = findblank(A)
B = copy(A)
if (blank / Nsq) > (Nsq -1)
return nothing
end
B[blank+Nsq],B[blank] = B[blank],B[blank+Nsq]
return B
end
function left(A::Array{Int64,1})
N = size(A,1)
Nsq = isqrt(N)
blank = findblank(A)
B = copy(A)
if (blank % Nsq) == 1
return nothing
end
B[blank-1],B[blank] = B[blank],B[blank-1]
return B
end
function right(A::Array{Int64,1})
N = size(A,1)
Nsq = isqrt(N)
blank = findblank(A)
B = copy(A)
if (blank % Nsq) == 0
return nothing
end
B[blank+1],B[blank] = B[blank],B[blank+1]
return B
end
function manhattan(A::Array{Int64,1})
N = size(A,1)
Nsq = isqrt(N)
r = 0
for i in 1:N
if (A[i]==i || A[i]==N)
continue
end
row1 = floor((A[i]-1) / Nsq)
col1 = (A[i]-1) % Nsq
row2 = floor((i-1) / Nsq)
col2 = (i-1) % Nsq
r+= abs(row1 - row2) + abs(col1 - col2)
end
return r
end
# start = [1,2,3,4,5,6,7,9,8]
# start = [6,5,4,1,7,3,9,8,2] #26 moves
start = [7,8,4,11,12,14,10,15,16,5,3,13,2,1,9,6] # 50 moves
goal = [x for x in 1:length(start)]
# println("The manhattan distance of $start is $(manhattan(start))")
g = 0
f = g + manhattan(start)
pq = PriorityQueue()
actions = [up,down,left,right]
dd = Dict{Array{Int64,1},Int64}()
snode = Node(C_NULL,f,start)
enqueue!(pq,snode,f)
pos_seen = 0
moves = 0
while (!isempty(pq))
current = dequeue!(pq)
if haskey(dd,current.board)
continue
else
push!(dd, current.board =>current.f)
end
if (current.board == goal)
while(current.board != start)
println(current.board)
global moves +=1
current = current.parent[]
end
println(start)
println("$start solved in $moves moves after looking at $pos_seen positions")
break
end
global pos_seen+=1
global g+=1
for i in 1:4
nextmove = actions[i](current.board)
if (nextmove === nothing || nextmove == current.board || haskey(dd,nextmove))
continue
else
global f = g+manhattan(nextmove)
n = Node(Ref(current),f,nextmove)
enqueue!(pq,n,f)
end
end
end
println("END")
I have created a fivem server for a friend of mine, and i'm currently having an issue with garages. Currently trying to index a nil value of 'spawnpoint'
for i=1, #v.Vehicles, 1 do
if GetDistanceBetweenCoords(coords, v.Vehicles[i].Spawner.x, v.Vehicles[i].Spawner.y, v.Vehicles[i].Spawner.z, true) < Config.MarkerSize.x then
isInMarker = true
currentStation = k
currentPart = 'VehicleSpawner'
currentPartNum = i
end
if GetDistanceBetweenCoords(coords, v.Vehicles[i].SpawnPoint.x, v.Vehicles[i].SpawnPoint.y, v.Vehicles[i].SpawnPoint.z, true) < Config.MarkerSize.x then
isInMarker = true
currentStation = k
currentPart = 'VehicleSpawnPoint'
currentPartNum = i
end
end
As brianolive already said, it seems like not every v.Vehicle has a SpawnPoint. You can fix this for instance by proofing for existence of SpawnPoint.
if v.Vehicles[i].SpawnPoint and (
GetDistanceBetweenCoords(
coords, v.Vehicles[i].SpawnPoint.x, v.Vehicles[i].SpawnPoint.y,
v.Vehicles[i].SpawnPoint.z, true
) < Config.MarkerSize.x
) then
I wrote a Lua code to arrange a list but when I enter any number with 2 decimals as 10, 20, etc. in the list, the variable 'ordenado' always takes the value 1 although whether it fulfills the conditions or not.
valor = {}
ordenado = 0
function inicializar ()
for i = 1,10 do
print ("Introduzca el valor "..i..":")
valor[i] = io.read()
end
end
function verificar ()
for i = 2, #valor do
if valor[i]>valor[i-1] then
ordenado = ordenado + 0
else
ordenado = ordenado + 1
end
print ("actual: "..valor[i].." \nanterior: "..valor[i-1].."\nordenado:"..ordenado.."\n")
end
end
function imprimir()
if ordenado == 0 then
print "La lista esta ordenada"
else
print "La lista no esta ordenada"
end
end
a = inicializar()
a = verificar()
a = imprimir()
The Lua version is 5.2.
The line valor[i] = io.read() stores a string in valor[i]. As strings, "2" > "10".
I am wanting to convert a 2d lua table into a string, then after converting it to a string convert it back into a table using that newly created string. It seems as if this process is called serialization, and is discussed in the below url, yet I am having a difficult time understanding the code and was hoping someone here had a simple table.toString and table.fromString function
http://lua-users.org/wiki/TableSerialization
I am using the following code in order to serialize tables:
function serializeTable(val, name, skipnewlines, depth)
skipnewlines = skipnewlines or false
depth = depth or 0
local tmp = string.rep(" ", depth)
if name then tmp = tmp .. name .. " = " end
if type(val) == "table" then
tmp = tmp .. "{" .. (not skipnewlines and "\n" or "")
for k, v in pairs(val) do
tmp = tmp .. serializeTable(v, k, skipnewlines, depth + 1) .. "," .. (not skipnewlines and "\n" or "")
end
tmp = tmp .. string.rep(" ", depth) .. "}"
elseif type(val) == "number" then
tmp = tmp .. tostring(val)
elseif type(val) == "string" then
tmp = tmp .. string.format("%q", val)
elseif type(val) == "boolean" then
tmp = tmp .. (val and "true" or "false")
else
tmp = tmp .. "\"[inserializeable datatype:" .. type(val) .. "]\""
end
return tmp
end
the code created can then be executed using loadstring(): http://www.lua.org/manual/5.1/manual.html#pdf-loadstring if you have passed an argument to 'name' parameter (or append it afterwards):
s = serializeTable({a = "foo", b = {c = 123, d = "foo"}})
print(s)
a = loadstring(s)()
The code lhf posted is a much simpler code example than anything from the page you linked, so hopefully you can understand it better. Adapting it to output a string instead of printing the output looks like:
t = {
{11,12,13},
{21,22,23},
}
local s = {"return {"}
for i=1,#t do
s[#s+1] = "{"
for j=1,#t[i] do
s[#s+1] = t[i][j]
s[#s+1] = ","
end
s[#s+1] = "},"
end
s[#s+1] = "}"
s = table.concat(s)
print(s)
The general idea with serialization is to take all the bits of data from some data structure like a table, and then loop through that data structure while building up a string that has all of those bits of data along with formatting characters.
How about a JSON module? That way you have also a better exchangeable data. I usually prefer dkjson, which also supports utf-8, where cmjjson won't.
Under the kong works this
local cjson = require "cjson"
kong.log.debug(cjson.encode(some_table))
Out of the kong should be installed package lua-cjson https://github.com/openresty/lua-cjson/
Here is a simple program which assumes your table contains numbers only. It outputs Lua code that can be loaded back with loadstring()(). Adapt it to output to a string instead of printing it out. Hint: redefine print to collect the output into a table and then at the end turn the output table into a string with table.concat.
t = {
{11,12,13},
{21,22,23},
}
print"return {"
for i=1,#t do
print"{"
for j=1,#t[i] do
print(t[i][j],",")
end
print"},"
end
print"}"
Assuming that:
You don't have loops (table a referencing table b and b referencing a)
Your tables are pure arrays (all keys are consecutive positive integers, starting on 1)
Your values are integers only (no strings, etc)
Then a recursive solution is easy to implement:
function serialize(t)
local serializedValues = {}
local value, serializedValue
for i=1,#t do
value = t[i]
serializedValue = type(value)=='table' and serialize(value) or value
table.insert(serializedValues, serializedValue)
end
return string.format("{ %s }", table.concat(serializedValues, ', ') )
end
Prepend the string resulting from this function with a return, store it on a .lua file:
-- myfile.lua
return { { 1, 2, 3 }, { 4, 5, 6 } }
You can just use dofile to get the table back.
t = dofile 'myfile.lua'
Notes:
If you have loops, then you will have
to handle them explicitly - usually with an extra table to "keep track" of repetitions
If you don't have pure arrays, then
you will have to parse t differently,
as well as handle the way the keys are rendered (are they strings? are they other tables? etc).
If you have more than just integers
and subtables, then calculating
serializedValue will be more
complex.
Regards!
I have shorter code to convert table to string but not reverse
function compileTable(table)
local index = 1
local holder = "{"
while true do
if type(table[index]) == "function" then
index = index + 1
elseif type(table[index]) == "table" then
holder = holder..compileTable(table[index])
elseif type(table[index]) == "number" then
holder = holder..tostring(table[index])
elseif type(table[index]) == "string" then
holder = holder.."\""..table[index].."\""
elseif table[index] == nil then
holder = holder.."nil"
elseif type(table[index]) == "boolean" then
holder = holder..(table[index] and "true" or "false")
end
if index + 1 > #table then
break
end
holder = holder..","
index = index + 1
end
return holder.."}"
end
if you want change the name just search all compileTable change it to you preferred name because this function will call it self if it detect nested table but escape sequence I don't know if it work
if you use this to create a lua executable file that output the table it will ge compilation error if you put new line and " sequence
this method is more memory efficient
Note:
Function not supported
User data I don't know
My solution:
local nl = string.char(10) -- newline
function serialize_list (tabl, indent)
indent = indent and (indent.." ") or ""
local str = ''
str = str .. indent.."{"
for key, value in pairs (tabl) do
local pr = (type(key)=="string") and ('["'..key..'"]=') or ""
if type (value) == "table" then
str = str..nl..pr..serialize_list (value, indent)..','
elseif type (value) == "string" then
str = str..nl..indent..pr..'"'..tostring(value)..'",'
else
str = str..nl..indent..pr..tostring(value)..','
end
end
str = str:sub(1, #str-1) -- remove last symbol
str = str..nl..indent.."}"
return str
end
local str = serialize_list(tables)
print('return '..nl..str)