finding minimum values from a cut table Lua 5.1.5 - lua

Question

I have a Lua script that turns a table into segments:
function tablecut(t, n)
local result = {}
local j = 0
for i = 1, #t do
if (i-1) % n == 0 then
j = j + 1
result[j] = {}
end
result[j][#result[j]+1] = t[i]
end
return result
end
output = tablecut({'15', '62', '14', '91', '33', '55', '29', '4'}, 4)
for i = 1, #output do
for j = 1, #output[i] do
io.write(tostring(output[i][j])..' ')
end
print()
end
output:
15 62 14 91
33 55 29 4
And I am trying to find the minima from the cut lists so the output would look like this:
15 62 14 91
min = 14
33 55 29 4
min = 4
Edit: If its of any importance this is how I got it to work on Lua 5.3 but there is no table.move function on Lua 5.1. I can't remember how my thought function worked when I wrote this code.
function indexOf(array, value)
for i, v in ipairs(array) do
if v == value then
return i
end
end
return nil
end
Indicies = {}
Answers = {}
function chunks(lst, size)
local i = 1
local count = 0
return function()
if i > #lst then return end
local chunk = table.move(lst, i, i + size -1, 1, {})
i = i + size
count = count + 1
return count, chunk
end
end
local a = {91,52,19,59,38,29,58,11,717,91,456,49,30,62,43,8,17,15,26,22,13,10,2,23} --Test list
for i, chunk in chunks(a, 4) do
x=math.min(a)
print(string.format("#%d: %s", i, table.concat(chunk, ",")))
table.sort(chunk)
print(math.min(chunk[1]))
table.insert(Answers, chunk[1])
table.insert(Indicies, (indexOf(a, chunk[1])))
Output:
#1: 91,52,19,59
19
#2: 38,29,58,11
11
#3: 717,91,456,49
49

Answer 1

your table cut function could be simplified, and your output for loop needs you use an iterator if you want to get an output simply like you do in your 5.3 script.
function cuttable(t,n)
local binned = {}
for i=1,#t,n do
local bin = {}
for j=1,n do
table.insert(bin, t[i + ((j - 1) % n)])
end
table.insert(binned, bin)
end
return binned
end
For the for loop, we can use ipairs on the output of cuttable keeping things pretty simple, then we just do the same steps of concat then sort and print out our results.
for k, bin in ipairs(cuttable(a,4)) do
local output = "#" .. k .. ":" .. table.concat(bin, ",")
table.sort(bin)
print(output)
print(bin[1])
end
Output
#1:91,52,19,59
19
#2:38,29,58,11
11
#3:717,91,456,49
49
#4:30,62,43,8
8
#5:17,15,26,22
15
#6:13,10,2,23
2

Answer 2

One way to implement the cutting would be using a for loop & unpack. I have handled the case of the length not being divisible by 4 after the for loop to (1) maximize performance (check doesn't need to be done every iteration) and (2) be able to directly pass the values to math.min, which doesn't accept nils.
for i = 1, math.floor(#t / 4), 4 do
print(unpack(t, i, i+4))
print("min = " .. math.min(unpack(t, i, i+4)))
end
-- If #t is not divisible by 4, deal with the remaining elements
local remaining = #t % 4
if remaining > 0 then
print(unpack(t, #t - remaining, remaining))
print("min = " .. math.min(unpack(t, #t - remaining, remaining)))
end