It is not recommended to create table in loop, get the data in variable(say cell data) then form table out of the loop
folderData = 'D:\Valerio\data\TEST';
filePattern = fullfile(folderData, '*.nc');
ncfiles = dir(filePattern);
nFiles = length(ncfiles);
% initialize variables
time1 = cell(nFiles, 1);
time2 = cell(nFiles, 1);
Hs_buoy = cell(nFiles, 1);
Tm_buoy = cell(nFiles, 1);
Dm_buoy = cell(nFiles, 1);
for i = 1:nFiles
filename = fullfile(ncfiles(i).folder, ncfiles(i).name);
ncdisp(filename);
lon = ncread(filename,'x');
lat = ncread(filename,'y');
%latitudine e longitudine
H_s = ncread(filename,'Hs');
T_m = ncread(filename,'Tm');
D_m = ncread(filename,'Dm');
time1{i} = ncread(filename,'time1'); %anno, mese e giorno
time2{i} = ncread(filename,'time2'); %ore, minuti e secondi
%uso lat=39.51 e lon=-0.3 che rappresenta la boa a largo di Valencia
buoy_lat = 39.51;
buoy_lon = -0.30;
S_lat = abs(buoy_lat - lat);
S_lon = abs(buoy_lon - lon);
F_lat = find(S_lat == min(S_lat));
F_lon = find(S_lon == min(S_lon));
Lat_1 = lat(F_lat);
Lon_1 = lon(F_lon);
if (buoy_lat > Lat_1);
PLat = find(lat == Lat_1);
PLat_1 = PLat + 1;
Lat_2 = lat(PLat_1);
else
PLat = find(lat == Lat_1);
PLat_1 = PLat - 1;
Lat_2 = lat(PLat_1);
end
if (buoy_lon > Lon_1)
PLon = find(lon == Lon_1)
PLon_1 = PLon + 1
Lon_2 = lon(PLon_1)
else
PLon = find(lon == Lon_1)
PLon_1 = PLon - 1
Lon_2 = lon(PLon_1)
end
%calcolo Hs
Hs_1 = H_s(PLon,PLat,:);
Hs_2 = H_s(PLon_1,PLat_1,:);
Hs_3 = H_s(PLon_1,PLat,:);
Hs_4 = H_s(PLon,PLat_1,:);
Hs1 = (Hs_1(1,:)).';
Hs2 = (Hs_2(1,:)).';
Hs3 = (Hs_3(1,:)).';
Hs4 = (Hs_4(1,:)).';
DLon = Lon_2 - abs(buoy_lon);
DLat_2 = buoy_lat - Lat_2;
DLat_3 = Lat_1 - buoy_lat;
d2 = sqrt(DLon^2 + DLat_2^2);
d3 = sqrt(DLon^2 + DLat_3^2);
%interpolazione lineare per ricavare i dati sulla boa
prod_sum = (Hs2 * d2) + (Hs3 * d3);
sum_d = d2 + d3;
Hs_buoy{i} = prod_sum / sum_d;
%calcolo Tm
Tm_1 = T_m(PLon,PLat,:);
Tm_2 = T_m(PLon_1,PLat_1,:);
Tm_3 = T_m(PLon_1,PLat,:);
Tm_4 = T_m(PLon,PLat_1,:);
Tm1 = (Tm_1(1,:)).';
Tm2 = (Tm_2(1,:)).';
Tm3 = (Tm_3(1,:)).';
Tm4 = (Tm_4(1,:)).';
prod_sum = (Tm2 * d2) + (Tm3 * d3);
sum_d = d2 + d3;
Tm_buoy{i} = prod_sum / sum_d;
%calcolo Dm
Dm_1 = D_m(PLon,PLat,:);
Dm_2 = D_m(PLon_1,PLat_1,:);
Dm_3 = D_m(PLon_1,PLat,:);
Dm_4 = D_m(PLon,PLat_1,:);
Dm1 = (Dm_1(1,:)).';
Dm2 = (Dm_2(1,:)).';
Dm3 = (Dm_3(1,:)).';
Dm4 = (Dm_4(1,:)).';
prod_sum = (Dm2 * d2) + (Dm3 * d3);
sum_d = d2 + d3;
Dm_buoy{i} = prod_sum / sum_d;
time1_str = num2str(time1);
time1_date{i} = datetime(time1_str,'InputFormat','yyyyMMdd','Format','yyyy/MM/dd');
% Data_table = table(time1_date, time2, Hs_buoy, Tm_buoy, Dm_buoy);
%x = time1;
%y = Hs_buoy;
%plot(x,y,'--ro');
%xlabel('time1');
%ylabel('Hs');
%title('trend of significant wave height');
%nameFile = 'Data.mat';
%save(nameFile, 'Data_table');
end
Data_table = table(time1_date, time2, Hs_buoy, Tm_buoy, Dm_buoy);
