Error using ls (line 47) zsh:1: no matches found: *pt*,I am trying to read multiple files for (nc data)but I get this error,and this is my code >>>

clc;clear;close all

x=1982:2023;
ao=[];
for x=1982:2023
    pt=['AOS_',num2str(x)];
    ls *pt*
    q=ls;
    c=1;
    for i=1:length(q)
        try
            ao(:,:,c)=ncread([pt,'\',q(i,:)],'sst');
            c=c+1;
        catch
        end
    end
 save(['AOS_',num2str(x)],'ao')
end

%%
lon=ncread([pt,'\',q(i,:)],'lon');
lat=ncread([pt,'\',q(i,:)],'lat');

save lon_lat.mat lon lat

[Cris LaPierre]

According to the error message, you have no files matching the pattern *pt* in your current folder.

You aren't doing anything with the result anyway. In order to capture the result, you need to use this syntax:

list = ls(___)

[B]

i get this message ,and the variple ao is empty

Index in position 1 exceeds array bounds. Index must not exceed 1.

[Cris LaPierre]

I don't see anywhere in the code you have shared that would generate this error message. Please share the full error message (all the red text).

The error is easy to reproduce. Somewhere in your code you are trying to index to a location that does not exist.

% create a 1x3 vector
a = 1:3;
% index a location that does not exist
a(2,1)

Index in position 1 exceeds array bounds. Index must not exceed 1.

Answer 1

[Umar]

Hi @B,

Let me explain the errors you have encountered.

No Matches Found: The error zsh:1: no matches found: pt implies that the shell is unable to find any files that match the wildcard pattern based on the variable pt. In your code, pt is dynamically constructed to represent folder names based on the year (e.g., AOS_1982, AOS_1983, etc.).

Empty Variable: The subsequent message indicating that the variable aois empty suggests that your attempt to read data into this array failed due to the absence of files.

Index Exceeds Array Bounds: This error occurs because you're trying to access elements in an empty array, which doesn't contain any data.

To resolve these issues, consider implementing the following changes:

Check Directory Existence: Before attempting to list files or read from them, check if the directory exists and contains files.

Correct File Listing: Instead of using ls pt, which might not correctly interpret pt, you can use MATLAB’s built-in functions to list files in a directory more reliably.

Improved Error Handling: Enhance your error handling by checking if the file list is empty before proceeding with reading operations.

Here’s a revised version of your code:

clc; clear; close all
x = 1982:2023;
ao = [];

for year = x
  pt = ['AOS_', num2str(year)];

    % Check if directory exists
    if exist(pt, 'dir') == 7  % 7 indicates it's a directory
        % Get list of NetCDF files in the directory
        filePattern = fullfile(pt, '*.nc');  % Adjust based on actual file extension
        q = dir(filePattern);

        if isempty(q)
            fprintf('No files found in %s\n', pt);
            continue;  % Skip to next iteration if no files found
        end

        c = 1;
        for i = 1:length(q)
            try
                % Read SST data
                ao(:,:,c) = ncread(fullfile(pt, q(i).name), 'sst');
                c = c + 1;
            catch ME
                fprintf('Error reading file %s: %s\n', q(i).name, ME.message);
            end
        end

        save(['AOS_', num2str(year)], 'ao');
      else
        fprintf('Directory %s does not exist.\n', pt);
    end
  end

% Assuming you want lon and lat from the last file read
if ~isempty(q)
  lon = ncread(fullfile(pt, q(end).name), 'lon');
  lat = ncread(fullfile(pt, q(end).name), 'lat');
  save('lon_lat.mat', 'lon', 'lat');
end

Ensure that your NetCDF files have a consistent naming convention and extension (e.g., .nc). Adjust the filePattern accordingly. Also, use error messages to log what went wrong when attempting to read files. This will help you debug issues related to specific files or paths.

By addressing these aspects, you should be able to successfully read your NetCDF data without encountering these errors.

If problems persist, ensure that you have the correct permissions for accessing directories and that your MATLAB environment is correctly set up for handling NetCDF files.

Hope this helps.