Brace indexing is not supported for this type of variable

Brace indexing not supported for this type of variable - error message, attached code, please support in resolving this issue

global new_files_all
            
            [load_file, ~] = uigetfile('.mat','File load','MultiSelect', 'on');
            
            new_files_all = load_file;           
            old_sname=extractBefore(load_file(1),'_');
            
            
            for i=1:length(load_file)
                 sname = extractBefore(load_file{i},'_');
            
            
                if i==1
            
                    load(load_file{i});
                    time=shdf.Absc1Data;
                    noise=shdf.Data(1,:);
                    rpm=shdf.Data(2,:);
                    snumber=1;
                    old_sname = sname;
            
                elseif (i>=2)
            
                   if  snumber == 1 && strcmp(old_sname, sname)
                       load(load_file{i});
                       time=shdf.Absc1Data;
                       noise=shdf.Data(1,:);
                       rpm=shdf.Data(2,:);
                        snumber=1;
            
                   elseif snumber >= 1 && strcmp(old_sname, sname)
                       load(load_file{i});
                       time=shdf.Absc1Data;
                       noise=shdf.Data(1,:);
                       rpm=shdf.Data(2,:);
                       snumber=snumber;
                       old_sname = sname;
            
                   elseif snumber >= 1 && ~strcmp(old_sname, sname)
                       load(load_file{i});
                       time=shdf.Absc1Data;
                       noise=shdf.Data(1,:);
                       rpm=shdf.Data(2,:);
                       snumber=snumber+1;
                       old_sname = sname;
                   end
                end
                
                new_files = {load_file{i}};

[Stephen23]

Why are you intentionally ignoring the filepath?

[F,P] = uigetfile('.mat','File load','MultiSelect', 'on');
F = cellstr(F); % <- this will probably fix that error

The class of UIGETFILE's output depends on how many files you select. Advice to simply use parenthesis indexing does not resolve that.

[Steven Lord]

Inside of a function I recommend always calling load with an output argument. How do you know that one of your files doesn't contain a variable named load_file that replaces your list of files with a scalar number? As a simpler example, what do you think the contents of the variable pop is after running these two lines of code?

pop = 42;
load census.mat

No, it's not 42, because census.mat contained a variable named pop that overwrote that number with a vector.

pop

pop = 21×1

3.9000 5.3000 7.2000 9.6000 12.9000 17.1000 23.1000 31.4000 38.6000 50.2000

[Kavinprasad M]

Yeah i can see the issue but my file will not have a variable named load_file since it's being directly exported from a data source i have externally which will only have certain input variable names

[Stephen23]

@Kavinprasad M: it is worth getting into the habit of writing more robust code, as Steven Lord recommends: the more you write it, the easier it becomes. And although you state that you are "certain" that the source only uses certain variable names, we get many many questions on this forum where the OP is "certain" of one thing or another... which turn out to be not true. The advice Steven Lord gave helps when the data is not as expected, as well as improving efficiency during its nominal/expected operation. Making code work is great... now you can upgrade your skills by controlling under what circumstances it will work and how it behaves when something unexpected happens. It will likely be more efficient to boot.

I second Steven Lord's recommendation: knowing how to write robust MATLAB code is definitely worth learning.

Answer 1

[Ayush Kashyap]

Error message like this one: "Brace indexing not supported for this type of variable" appears mainly when curly braces "{}" are used for indexing instead of parantheses "()".

Looking at your code, I believe the issue is happeneing because of lines like this one:

sname = extractBefore(load_file{i},'_');

Try using parantheses as follows:

sname = extractBefore(load_file(i),'_');

Similarly, try to check your whole code once and replace all instances where you have used "{}" for indexing with "()".

Reference Link: Indexing in Matlab

Answer 2

[Image Analyst]

I think this is closer to what you want. It has many improvements. I'm not sure what you want with that sname stuff so there still may be errors.

global new_files_all
% Get a file specification.
folder = pwd; % Wherever you want.
filePattern = fullfile(folder, '*.mat');
% Ask user to select files.
[baseFileNames, folder] = uigetfile(filePattern,'File load','MultiSelect', 'on');
if folder == 0
    fprintf('You clicked Cancel.\n');
    return; % User clicked cancel.
end
numberOfFiles = numel(baseFileNames)
new_files_all = cell(numberOfFiles, 1);
old_sname=extractBefore(folder(1),'_'); % Not sure what this is for.
for k = 1 : numberOfFiles
    thisFileName = fullfile(folder, baseFileNames{k});
    fprintf('Processing %s (#%d of %d)\n', thisFileName, k, numberOfFiles);
    sname = extractBefore(thisFileName,'_');
    if k==1
        load(thisFileName);
        time=shdf.Absc1Data;
        noise=shdf.Data(1,:);
        rpm=shdf.Data(2,:);
        snumber=1;
        old_sname = sname;
    elseif (k>=2)
        if  snumber == 1 && strcmp(old_sname, sname)
            load(thisFileName);
            time=shdf.Absc1Data;
            noise=shdf.Data(1,:);
            rpm=shdf.Data(2,:);
            snumber=1;
        elseif snumber >= 1 && strcmp(old_sname, sname)
            load(thisFileName);
            time=shdf.Absc1Data;
            noise=shdf.Data(1,:);
            rpm=shdf.Data(2,:);
            snumber=snumber;
            old_sname = sname;
        elseif snumber >= 1 && ~strcmp(old_sname, sname)
            load(thisFileName);
            time=shdf.Absc1Data;
            noise=shdf.Data(1,:);
            rpm=shdf.Data(2,:);
            snumber=snumber+1;
            old_sname = sname;
        end
    end
    new_files{k} = thisFileName;
end

[Kavinprasad M]

Thankyou, this code is better but it still throws the same error for baseFileNames{k}

Attached complete application