How to loop all slice locations from a image volume as a single column vector?

Hello, I am reading DICOM images from a folder and want to read all image slice locations such that I can have all slice locations as a column vector (I have 71 slices, so want to have 71 slice locations). Below is my attempt but could not able to figure out the way, can anyone help me?

%%
close all; clear; clc;

%% 
% List all files in the folder
Files = dir('/etc/*');

for k = 1 : length(Files)
    baseFileName = Files(k).name;
    fullFileName = fullfile(Files(k).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
end

%%
info = dicominfo(fullFileName);

slLoc = info.SliceLocation; % this will throw the slice location of the last Dicom image

% I want to write slLoc in a column vector such that all image slice locations are listed

Answer 1

[Voss]

Move the last two lines inside the loop and assign info.SliceLocation to the kth element of slLoc:

%%
close all; clear; clc;

%% 
% List all files in the folder
Files = dir('/etc/*');

% slLoc = zeros(numel(Files),1); % pre-allocate slLoc
slLoc = cell(numel(Files),1); % pre-allocate slLoc

for k = 1:numel(Files)
    
    baseFileName = Files(k).name;
    fullFileName = fullfile(Files(k).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    
    info = dicominfo(fullFileName);
%     slLoc(k,1) = info.SliceLocation;
    slLoc{k,1} = info.SliceLocation;
    
end

I don't know what class of data SliceLocation will be, so I've put it in a cell array there. Maybe it can be a numeric array or a string array.

[blues]

Running this throws the following error:

Error using fseek

Invalid file identifier. Use fopen to generate a valid file identifier.

Error in dicom_getFileDetails>getFileLength (line 33)

fseek(fid, 0, 'eof');

Error in dicom_getFileDetails (line 21)

details.bytes = getFileLength(fid);

Error in dicominfo (line 55)

fileDetails = dicom_getFileDetails(filename);

Error in testhundred (line 36)

info = dicominfo(fullFileName);

Any hints on this?

[Image Analyst]

Try this - it works for me.

% List all files in the folder
Files = dir('\etc\**\*.dcm')
% slLoc = zeros(numel(Files),1); % pre-allocate slLoc
slLoc = cell(numel(Files),1); % pre-allocate slLoc
for k = 1 : numel(Files)
    baseFileName = Files(k).name;
    fullFileName = fullfile(Files(k).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    info = dicominfo(fullFileName);
    %     slLoc(k,1) = info.SliceLocation;
    if isfield(info, 'SliceLocation')
        slLoc{k,1} = info.SliceLocation;
    end
end
slLoc

[blues]

Thank you - this works for me too. But when I tried to sort slLoc then it throws an error - Input argument must be a cell array of character vectors.

How can I sort this slLoc vector such that I can write an ascending vector?

I tried: slLoc = sort(slLoc); but this did not work!

[Voss]

Sounds like (maybe) slLoc is a cell array of numeric scalars, in which case you can make it a numeric array instead:

% List all files in the folder
Files = dir('\etc\**\*.dcm')
slLoc = zeros(numel(Files),1); % pre-allocate slLoc
for k = 1 : numel(Files)
    baseFileName = Files(k).name;
    fullFileName = fullfile(Files(k).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    info = dicominfo(fullFileName);
    if isfield(info, 'SliceLocation')
        slLoc(k,1) = info.SliceLocation;
    end
end
slLoc = sort(slLoc)

[blues]

Voss: I tried it but error says -- Conversion to cell from double is not possible.

[Voss]

Check the pre-allocation line, before the loop:

slLoc = zeros(numel(Files),1); % pre-allocate slLoc

(not a cell array - a vector of zeros).

[blues]

This works great - thank you.

[Voss]

You're welcome! Glad you got it working!