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Error Brace indexing is not supported

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Hi there,
I am having an odd problem, and I'm not sure how to fix the error below. Any assistance would be greatly appreciated.
Brace indexing is not supported for variables of this type.
Many thanks
Following is the code i am using
imageFileNames = imageFileNames(imagesUsed);
originalImage = imread(imageFileNames{1});
Brace indexing is not supported for variables of this type.
class(imageFileNames)
ans =
'char'
imageFileNames
imageFileNames =
'rcngvieo ram'
where imagesUsed =
25×1 logical array
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  3 Comments
Life is Wonderful
Life is Wonderful on 4 Apr 2023
Do you expect imageFileNames to be a cell array
This is not a cell array, it's a char
class(imageFileNames)
ans =
'char'
Stephen23
Stephen23 on 4 Apr 2023
"This is not a cell array, it's a char "
Sure, which is exactly why you cannot use curly brace indexing with it.
However I did not ask you what it is, I asked you what you expect it to be. A totally different question.

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Accepted Answer

Image Analyst
Image Analyst on 4 Apr 2023
Edited: Image Analyst on 4 Apr 2023
How did you get imageFileNames? Was it from using dir somehow?
% Get file listing of all PNG files in the current folder.
fileList = dir('*.png');
% Convert from structure to cell array.
imageFileNames = {fileList.name};
% Load that cell array into a listbox.
handles.listbox1.String = imageFileNames;
Was it from a listbox of file names that you had loaded up previously? Then you can do
% Get a list of all filenames in the listbox.
imageFileNames = handles.listbox1.String;
% Get the indexes the user selected.
imagesUsed = handles.listbox1.Value;
% Extract the selected names into a subset.
selectedImageFileNames = imageFileNames(imagesUsed);
% Get the name of the first one that was selected:
firstImageFileName = imread(selectedImageFileNames{1});
[EDIT}
Most likely the problem was you did this
imageFileNames = [fileList.name] % Used brackets to concatenate.
instead of this
imageFileNames = {fileList.name} % Should use braces to concatenate.
That will give you spaces in the name and make a long character array, rather than a cell array.
See the FAQ to learn when to use parentheses, braces, and brackets:
  6 Comments
Image Analyst
Image Analyst on 4 Apr 2023
That's not how you do it. Try this
imds = imageDatastore({PathToimageFileNames},"FileExtensions",[".png", ".jpg",".tif"]);
imageFileNames = imds.Files
Life is Wonderful
Life is Wonderful on 4 Apr 2023
It's perfect!!!! You've got the problem under control, now I can see
imageFileNames = imageFileNames(imagesUsed);
K>> class(imageFileNames)
ans =
'cell'
Your proposal work well.
Thank you

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More Answers (1)

Bora Eryilmaz
Bora Eryilmaz on 4 Apr 2023
Edited: Bora Eryilmaz on 4 Apr 2023
Your imageFileNames variable is not a cell array, so you cannot use brace indexing with it. It is a long char array with words separated by spaces. You can use the split command to generate a cell array of char variables from it:
imageFileNames = 'rcngvieo ram'
imageFileNames = 'rcngvieo ram'
names = split(imageFileNames, ' ')
names = 2×1 cell array
{'rcngvieo'} {'ram' }
names{1}
ans = 'rcngvieo'
names{2}
ans = 'ram'
  3 Comments
Bora Eryilmaz
Bora Eryilmaz on 4 Apr 2023
I am assuming 'ram' is the file extension for your image file. If that is the case, the way you construct the imageFileNames variable is problematic. The imread command needs the full name of the file, including the file extension.
Life is Wonderful
Life is Wonderful on 4 Apr 2023
No, it was a logical index that was changed to a char rather than a cell.

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