How to save data from every file in a folder

Hi everyone,

I made the code below that read and compute every file in a folder with for loop. Now, I should to save the data (time1, time2, Hs_buoy, Tm_buoy, Dm_buoy) of each file in a table but I have no idea how to do. For now, the code save the data of first file only. Thanks.

folderData = 'D:\Valerio\data\TEST';
filePattern = fullfile(folderData, '*.nc'); 
ncfiles = dir(filePattern);
nFiles = length(ncfiles);

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 = ncread(filename,'time1'); %anno, mese e giorno
    time2 = 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 = 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 = 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 = prod_sum / sum_d;
    
    time1_str = num2str(time1);
    time1_date = 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

Answer 1

[Bhaskar R]

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);

[Valerio Gianforte]

Sorry but it doesn't work, there is a problem with 'num2str'.

[Bhaskar R]

can you post complete error?

[Valerio Gianforte]

Error using num2str (line 53)
Input to num2str must be numeric.

Error in valerio_TEST (line 113)
    time1_str = num2str(time1);

[Bhaskar R]

okay replace

time1_str = num2str(time1);

to

time1_str = num2str(time1{i});

[Valerio Gianforte]

Now Ihave this error:

Error using table (line 231)
All input variables must have the same number of rows.

Error in valerio_TEST (line 127)
Data_table = table(time1_date, time2, Hs_buoy, Tm_buoy, Dm_buoy);
 

[Bhaskar R]

That means your all variables must have the same length, check each variable those are inputs to the table after loop

[Valerio Gianforte]

I fixed the problem but I would like to obtain a table 125x5 that contain all data from the files. Now, I have a table 12x5 where the each element is a vector with dimension 125x5. Is there a way to do this?