Comparing two matrices to find and eliminate similarities?

This is a simplified example. I have two tables created by pulling info from multiple files, file names and size..

%Grab Folder from directory, class(char)
dir_QAR1 = uigetdir();
% Folder info, class(struct), names, dates, bytes, etc.
QAR1 = dir(dir_QAR1);
length_QAR1 = length(QAR1);

%Repeat
dir_QAR2 = uigetdir();
QAR2 = dir(dir_QAR2);
length_QAR2 = length(QAR2);

Extract file names, class(cell)

files_QAR1 = {QAR1.name}';
files_QAR2 = {QAR2.name}';

%Extract file sizes, class(cell)
bytes_QAR1 = {QAR1.bytes}';
bytes_QAR2 = {QAR2.bytes}';

%create a table of file names and sizes, class(cell)
package_QAR1 = [files_QAR1, bytes_QAR1];
package_QAR2 = [files_QAR2, bytes_QAR2];

%Output
package_QAR1 = 

      '.'                [       0]
      '..'               [       0]
      'CM38.xps'         [  446756]
      'CM39_005.xls'     [  134144]
      'CM76.xps'         [  287673]
      'CM37_002.pptx'    [ 1860347]
      'CM96.xps'         [  291920]
%...many more rows

Example tables, not actual output. Referencing package_QAR1 and package_QAR2

% File Name, File Size
package_QAR1 = 

        'a'   [1]
        'b'   [2]
        'c'   [3] 
        'd'   [4] 
        'e'   [5]

package_QAR2 = 

        'a'   [1]
        'b'   [2] 
        'c'   [4]
        'd'   [4]
        'x'   [1]
        'e'   [5]
        'f'   [6]
        'g'   [7]
        'h'   [8]

I would like to compare table data. If name (a) has the same size (1) in both tables, delete field in package_QAR2. Output new table (X) showing items that had the same name but different size. Should return a table with the following info (not actual outputs)..

package_QAR2_2 = 

        'c'   [4]
        'x'   [1]
        'f'   [6]
        'g'   [7]
        'h'   [8]

    X = 

        'c'   [4]

It is important to note that file names are not in any consistent order and table lengths vary.

Please note the example tables aren't actual outputs, they are included to merely reference data being kept/ removed.

[Jan]

What is the type of the shown matrices and "a", "b" etc? Is it a table? I cannot imagine the meaning of "[a, 1]". Please post some valid Matlab code, which creates the data.

[Calabrese]

I have modified my question details to be more specific.

[Walter Roberson]

You should be using cell arrays if you need to mix data types in an array.

[Jan]

@Calabrese: This is still no valid Matlab code. Try to copy&paste it in the command window:

A = ['a', 1;
    'b', 2; 
    'c', 3; 
    'd', 4; 
    'e', 5];

You cannot mix chars and numbers in a matrix. Do you mean:

A = {'a', 1;
    'b', 2; 
    'c', 3; 
    'd', 4; 
    'e', 5};  % Cell-array: Curly braces

I have no idea about the meaning of the first 12 lines of code from "dir_QAR1 = uigetdir();" to "size_QAR2 = [files_QAR2, bytes_QAR2];". Does this code have any connection to the question?

[Calabrese]

I apologize for the confusion, I hope it is more clear now. Please note the example tables aren't actual outputs, they are included to merely reference data being kept/ removed.

[Jan]

@Calabrese: I admit that I'm completely confused now. Are the input data table objects or cells? Could you please post some code, which creates the wanted input by copy&pasting it to the command window?

Answer 1

[Jan]

When I ignore the ambiguities, perhaps you need something like this:

A = {'a', 1;
     'b', 2; 
     'c', 3; 
     'd', 4; 
     'e', 5};

B = {'a', 1;
     'b', 2; 
     'c', 4;
     'd', 4;
     'x', 1;
     'e', 5;
     'f', 6;
     'g', 7;
     'h', 8};

[LiB, iA] = ismember(B(:, 1), A(:, 1));
match     = (cat(1, A{iA(iA~=0), 2}) == cat(1, B{LiB, 2}));
index     = find(LiB);
C         = B(index(~match), :);
B(index(match), :) = [];

[Calabrese]

I realize the question didn't include enough information. I was originally hoping to keep it very simple. Please see the current updates.

[Jan]

@Calabrese: It would be useful if you add any comment concerning the suggested solutions. Does my code help you or not? Did I guess correctly, that your inputs are cells (as the code looks like), or are you talking about table objects (as the text seems to imply)?

[Calabrese]

It is a cell array, yes. However when I run the code I get the following error.

Error using cat. Dimensions of matrices being concatenated are not consistent.

[Jan]

What do you get if you run the code I have posted by copy&paste? On my Matlab no error occurres, but the wanted output for B and C. If you get something else, I assume you have different inputs. Then please please please post your inputs exactly how they are. I've asked 4 days ago for some real inputs already. Give me a chance to help you.

You can use the debugger by your own also. Type this in the command window:

dbstop if error

Then run the code again. If it stops at the error, (I guess it is here - if you post a copy of the complete message, less guessing would be reuired)

match = (cat(1, A{iA(iA~=0), 2}) == cat(1, B{LiB, 2}));

check the dimensions:

cellfun('size', A(iA(iA~=0), 2), 1)
cellfun('size', A(iA(iA~=0), 2), 2)
cellfun('size', B(LiB, 2), 2), 1)
cellfun('size', B(LiB, 2), 2), 2)

Do you see the reason, why a concatenation does not work?

[Calabrese]

Here is the code.

clear all
clc

%Grab Folder from directory, class(char)
dir_QAR1 = uigetdir();
% Folder info, class(struct), names, dates, bytes, etc.
QAR1 = dir(dir_QAR1);
length_QAR1 = length(QAR1);

%Repeat
dir_QAR2 = uigetdir();
QAR2 = dir(dir_QAR2);
length_QAR2 = length(QAR2);

Extract file names, class(cell)

files_QAR1 = {QAR1.name}';
files_QAR2 = {QAR2.name}';

%Extract file sizes, class(cell)
bytes_QAR1 = {QAR1.bytes}';
bytes_QAR2 = {QAR2.bytes}';

%create a table of file names and sizes, class(cell)
package_QAR1 = [files_QAR1(3:length_QAR1,1), bytes_QAR1(3:length_QAR1,1)];
package_QAR2 = [files_QAR2(3:length_QAR2,1), bytes_QAR2(3:length_QAR2,1)];

package_QAR1 = cellfun(@num2str,package_QAR1,'UniformOutput',0);
package_QAR2 = cellfun(@num2str,package_QAR2,'UniformOutput',0);

[Lipackage_QAR2, ipackage_QAR1] = ismember(package_QAR2(:, 1), package_QAR1(:, 1));

what1 = cellfun('size', package_QAR1(ipackage_QAR1(ipackage_QAR1~=0), 2), 1);
what2 = cellfun('size', package_QAR1(ipackage_QAR1(ipackage_QAR1~=0), 2), 2);
what3 = cellfun('size', package_QAR2(Lipackage_QAR2, 2), 1);
what4 = cellfun('size', package_QAR2(Lipackage_QAR2, 2), 2);

match     = (cat(1, package_QAR1{ipackage_QAR1(ipackage_QAR1~=0), 2}) == cat(1, package_QAR2{Lipackage_QAR2, 2}));
index     = find(Lipackage_QAR2);
C         = package_QAR2(index(~match), :);
package_QAR2(index(match), :) = [];

The error is at

match = ****

what1, what2, what3, what4 are all 143x1 double. I have no idea why concatenation isn't working.

[Jan]

@Calabrese: Note that I cannot run your code, because the files are not existing on my computer. Therefore you are the only person who can debug the code.

what1 = cellfun('size', package_QAR1(ipackage_QAR1(ipackage_QAR1~=0), 2), 1);
what2 = cellfun('size', package_QAR1(ipackage_QAR1(ipackage_QAR1~=0), 2), 2);
what3 = cellfun('size', package_QAR2(Lipackage_QAR2, 2), 1);
what4 = cellfun('size', package_QAR2(Lipackage_QAR2, 2), 2);

all(what1 == what1(1))
all(what2 == what2(1))
all(what3 == what3(1))
all(what4 == what4(1))

Does this really reply TRUE 4 times?

Try to find out which of the cat() command fails:

cat(1, package_QAR1{ipackage_QAR1(ipackage_QAR1~=0), 2})
cat(1, package_QAR2{Lipackage_QAR2, 2})

Ah, well, I see, that you apply @num2str to the data. Then the 2nd column are not scalar doubles, but char vectors of different size:

A = {'a', '1';
     'b', '12'};

not

A = {'a', 1;
     'b', 12};

Correct? Then the concatenation must fail.

What is the prupose of this:

cellfun(@num2str,package_QAR1,'UniformOutput',0);

Note that this changes the type of the inputs again. I'm asking you for 6 days repeatedly for the correct type of the inputs. And after posting an answer and discussing in the comments, you change the input type again compared to the text of the question. This is not a useful strategy to solve a problem.

I suggest to omit the cellfun(@num2str).

The code would look much cleaner, if you move my suggested code inside a function and keep the lean names for the variables.

[Calabrese]

Your original solution worked. I had changed my original code in the beginning hoping it might bring me to a solution which prevented your solution from working. I made the changes and it works like a charm. This is extremely helpful, thank you.