How could I do to delete repeated values in a table? Ex:
a = {1,2,3,4,3,2,1}
How would you erase 3, 2, and 1, keeping only one of each?
My table is one inside another:
a = {
{a=1, b=2},
{a=2, b=3},
{a=1, b=2},
}
In this case, the last value would be erased, since the a and the b of it and the first are equal. Pairs should be considered as a value for comparison purposes only. How to do this?
A more traditional approach to verifying duplicity as I had already done in another answer on C .
a = {{a=1, b=2}, {a=2, b=3}, {a=1, b=2}, {a=3, b=2}, {a=1, b=2}}
for i = #a, 2, -1 do
for j = i - 1, 1, -1 do
if (a[j].a == a[i].a and a[j].b == a[i].b) then
table.remove(a, i)
break
end
end
end
-- demonstração do resultado:
for i, j in pairs(a) do
print(i .. ". a=" .. j.a .. ", b=" .. j.b)
end
See running on ideone . And no Coding Ground . Also I placed GitHub for future reference .
You can create other tables and use flags as flags to see if the element is already in the array or not. If your table has tables inside, just iterate through each table inside the first table:
local flags = {}
local a_filtrado = {}
for _, f in pairs(a) do
for _,v in pairs(f) do
if (not flags[v]) then
a_filtrado[#a_filtrado+1] = v
flags[v] = true
end
end
end
The a_filtrado table will have the elements only once.