CODEWITHSUNDEEP
lualua-table
Sean
Sean

Reputation: 105

Find the table entry with the largest nested value

With a Lua table nested like this, how can I find the winning entry with the highest value? In other words, I would like to iterate over the table and get the answer "Banana."

[1] = {
  ['name'] = 'Apple',
  ['qty'] = 3,
},
[2] = {
  ['name'] = 'Orange',
  ['qty'] = 6,
},
[3] = {
  ['name'] = 'Kiwi',
  ['qty'] = 2,
},
[4] = {
  ['name'] = 'Banana',
  ['qty'] = 8,
},

Upvotes: 1

Views: 34

Answers (1)

Luatic
Luatic

Reputation: 11171

This is a straightforward running maximum by looping over the table once while remembering associated sentinel data:

local t = {[1] = {
  ['name'] = 'Apple',
  ['qty'] = 3,
},
[2] = {
  ['name'] = 'Orange',
  ['qty'] = 6,
},
[3] = {
  ['name'] = 'Kiwi',
  ['qty'] = 2,
},
[4] = {
  ['name'] = 'Banana',
  ['qty'] = 8,
}}
local highest_qty, name = t[1].qty, t[1].name
for i = 2, #t do
    if t[i].qty > highest_qty then
        highest_qty, name = t[i].qty, t[i].name
    end
end
print(name) -- Banana

Various variants of this exist, potentially using ipairs, introducing some local variables, using a default value of -math.huge and a default name of nil (if the table can be empty), etc.

Upvotes: 2

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