"Error using textscan Invalid file identifier. Use fopen to generate a valid file identifier." - why am i getting this error?

function allHurricaneData = getAllHurricaneData(allHurricanesFileName)

%UNTITLED2 Summary of this function goes here

% Detailed explanation goes here

FID = fopen(['data/' allHurricanesFileName]);

allNames = textscan(FID,'%s');

for i = 1:length(allNames{1})

hurricaneName = ['data/' allNames{1}{i}];

openFile = fopen(hurricaneName)

headerLine = fgetl(openFile);

properties = textscan(openFile,'%s %s %f %f %f %f %d %d' ,'Delimiter',',');

nameVariable =split(allNames{1}{i},'.');

allHurricaneData(i).name = nameVariable{1};

allHurricaneData(i).date = properties{1};

allHurricaneData(i).Xs = properties{5};

allHurricaneData(i).Ys = properties{6};

allHurricaneData(i).wind = properties{7};

allHurricaneData(i).pressure = properties{8};

end

end

Answer 1

[Voss]

Most likely you get that error because the file ['data/' allHurricanesFileName] does not exist.

To find out for sure, you can take a look at the second output from fopen, which is an error message in case fopen cannot open the file:

[FID,msg] = fopen(['data/'  allHurricanesFileName]);
if FID < 0
    error('Cannot open the file: %s',msg);
end
allNames = textscan(FID,'%s'); 

fopen

Answer 2

[Image Analyst]

Replace this

for i = 1:length(allNames{1})
    hurricaneName = ['data/'  allNames{1}{i}];
    openFile = fopen(hurricaneName)   

with this more robust code that has error checking in it:

for i = 1:length(allNames{1})
    hurricaneName = ['data/'  allNames{1}{i}];
    if ~isfile(hurricaneName)
        % File not found.  Perhaps the folder name was not prepended with fullfile().
        warningMessage = sprintf('Warning: this file does not exist:\n%s', hurricaneName)
        uiwait(warndlg(warningMessage))
        continue; % Skip to bottom of loop and keep going.
    end
    openFile = fopen(hurricaneName)   
    if openFile == -1
        % Could be due to a variety of things, like it's open and locked in
        % another application.
        warningMessage = sprintf('Warning: error opening this file :\n%s', hurricaneName)
        uiwait(warndlg(warningMessage))
        continue; % Skip to bottom of loop and keep going.
    end
    % If you get here, it worked.
    fprintf('Just opened :\n%s\n', hurricaneName)