how to access data in such table? - lua

Question

I'm writing a program with lua. I have data that organized in the following way:
t= {
i1 = {
p1 = { value = "i1p1" },
p2 = { value = "i1p2" },
-- etc
pm = { value = "i1pm" }
},
i2 = {
p1 = { value = "i2p1" },
p2 = { value = "i2p2" },
-- etc
pm = { value = "i2pm" }
},
im = {
p1 = { value = "imp1" },
p2 = { value = "imp2" },
-- etc
pm = { value = "impm" }
}
} --(inner tables)
In another way each group of data is indexed by two variables i&p,I am sure that the data is kept correctly but I want a way to print the data from their tables because I won't know the values of i and p to iterate over them or even the numbers n & m any body know how to do this with lua?

Answer 1

If you know the depth of your nested (inner) tables, you can iterate explicitly to that depth:
for k1,v1 in pairs(t) do
for k2,v2 in pairs(v1) do
for k3, v3 in pairs(v2) do
print(k3, ":", v3)
end
end
end
Alternatively, you can recursively iterate into your nested structure:
function print_tbl(tbl)
if type(tbl) == "table" then
for _,v in pairs(tbl) do
print_tbl(v)
end
else
print(tbl)
end
end
print_tbl(t)
This is just an example. If your tables contain functions, contains userdata, or your nesting has cycles, you'll need a different approach. Take a look at table serialization on the Lua user wiki. Serialization requires sensible handling of tables with nesting, functions, cycles, etc. You may be able to use lessons learned on your data.