LUA - how to loop less times than entries in a table? - loops

Question

LUA neewb having trouble with all the different ways of looping.
I adjusted a template script for mapping audio files in my filesystem to an audio sampler software, where each audio file goes into 1 group --> zone --> file.
This works as intended but now for a "Lite-Version" package of the software I only need some of the samples from my computer and this is where I'm having problems with my loop functions.
This is the function causing issues:
for index, file in next, samples do
...
The table "samples" consists of 180 samples but I'm only creating 38 groups and zones in the audio software for putting audio files into, so obviously this returns an error.
ERROR:
" ...- PATH.LINE: bad argument #2 to '--index' (invalid index, size is 58 got 58)"
The 58 makes sense because it is 38 sample groups + 18 empty groups + 2 template groups that get duplicated.
Since that is still smaller than 180 it wants to keep going and I'm not sure how to tell it to stop there.
CODE:
local samples = {}
local root = 0
-- [[ FILE SYSTEM]]
local i = 1
for _,p in filesystem.directoryRecursive(folderPath) do
if filesystem.isRegularFile(p) then
if filesystem.extension(p) == '.wav' or filesystem.extension(p) == '.aif' or filesystem.extension(p) == '.aiff' then
samples[i] = p
i = i+1
end
end
end
After this I create the amount of groups I need in the audio software (38).
A group contains a zone which contains a sample
-- [[ ZONES & FILES ]]
-- Create zones and place one file in each of the created groups.
-- file is a string property of the object Zones
-- samples is a table, populated with paths to our samples
for index, file in next, samples do
-- Initialize the zone variable.
local z = Zone()
-- Add a zone for each sample.
instrument.groups[index +1].zones:add(z)
-- Populate the attached zone with a sample from our table.
z.file = file
-- detect and set root note
local detectedPitch = mir.detectPitch(index)
z.rootKey = math.floor(detectedPitch + 0.5)
end
So my question is: how do I loop through the table samples but only do it up to 38 and not to 180?
I could do
for index = 1, #NUM_FACT_LAYERS do
but what do I do about file then?
Samples only has the paths to the files but z.file needs the string of the file.
z.file = file won't work in this case.
I guess that's why the previous script used for for in