(matlab) qtdecomp works with uint8 matrix? - matlab

I haven't fully understood how qtdecomp works...
I = [1 1 1 1 2 3 6 6
1 1 2 1 4 5 6 8
1 1 1 1 10 15 7 7
1 1 1 1 20 25 7 7
20 22 20 22 1 2 3 4
20 22 22 20 5 6 7 8
20 22 20 20 9 10 11 12
22 22 20 20 13 14 15 16];
S = qtdecomp(I,2);
disp(full(S));
The results of this are:
4 0 0 0 1 1 2 0
0 0 0 0 1 1 0 0
0 0 0 0 1 1 2 0
0 0 0 0 1 1 0 0
4 0 0 0 1 1 1 1
0 0 0 0 1 1 1 1
0 0 0 0 1 1 1 1
0 0 0 0 1 1 1 1
in the left bottom 4*4 matrix, maximum value (22) of the block elements minus the minimum value (20) is 2, so when decomposing this part, it will left as is.
When I do this on a uint8 matrix:
I = uint8([...
1 1 1 1 2 3 6 6
1 1 2 1 4 5 6 8
1 1 1 1 10 15 7 7
1 1 1 1 20 25 7 7
20 22 20 22 1 2 3 4
20 22 22 20 5 6 7 8
20 22 20 20 9 10 11 12
22 22 20 20 13 14 15 16]);
S = qtdecomp(I,2/255);
disp(full(S));
the answer is just like before. But when I change S to this:
S = qtdecomp(I,1.9/255);
The answer is
4 0 0 0 1 1 2 0
0 0 0 0 1 1 0 0
0 0 0 0 1 1 2 0
0 0 0 0 1 1 0 0
4 0 0 0 1 1 1 1
0 0 0 0 1 1 1 1
0 0 0 0 1 1 1 1
0 0 0 0 1 1 1 1
I suppose the left bottom 4*4 matrix should decompose, but why doesn't it?


What matlab does here is when I is uint8 it multiples the threshold by 255 and rounds it, so 1.9/255 is evaluated to 2.
You can see this by opening the source code for qtdecomp (by pressing ctrl+D) or here. There's an if/elseif near the end of the file (params{1} = round(255 * params{1});).
You should be able to use S = qtdecomp(I,1/255); to get the result you are looking for.

Related

How to create a constant vector by variant arrays of numbers?

I have a vector ("d") which I want to place it's content to a matrix ("dis"), I have the problem to create "dis" matrix. "dis" should be like
dis=[
1 2 3 4 5 6 7 8 9 10 11 12
0 1 2 3 4 5 6 7 8 9 10 11
0 0 1 2 3 4 5 6 7 8 9 10
0 0 0 1 2 3 4 5 6 7 8 9
0 0 0 0 1 2 3 4 5 6 7 8
0 0 0 0 0 1 2 3 4 5 6 7
0 0 0 0 0 0 1 2 3 4 5 6
0 0 0 0 0 0 0 1 2 3 4 5
0 0 0 0 0 0 0 0 1 2 3 4
0 0 0 0 0 0 0 0 0 1 2 3
0 0 0 0 0 0 0 0 0 0 1 2
0 0 0 0 0 0 0 0 0 0 0 1];
n=[0,0;1,0;2,0;3,0;4,0;5,0;6,0;7,0;8,0;9,0;10,0;11,0;12,0];
d=pdist(n,'euclidean');
l=length(n)-1;
dis=[];
for k=1:length(n)-1
dis=[dis;d((k-1)*l-(k*((k-1)/2))+k):d(k*l-((k+1)*k/2)+k)];
end

The problem is that you are not padding dis with the zeros.
You can replace
dis=[];
for k=1:length(n)-1
dis=[dis;d((k-1)*l-(k*((k-1)/2))+k):d(k*l-((k+1)*k/2)+k)];
end
with
dis = zeros(l);
for k=1:l
dis(k,k:end) = d((k-1)*l-(k*((k-1)/2))+k):d(k*l-((k+1)*k/2)+k)
end

Using squareform form #beaker comment above, you can write:
dis = triu(squareform(d));
dis = dis(1:length(dis)-1,2:length(dis));
Does this solves the problem?

Concatenating binary bits into a number

I want to concatenate last four bits of binary into a number i have tried the following code
x8=magic(4)
x8_n=dec2bin(x8)
m=x8_n-'0'
which gives me the following output
m =
1 0 0 0 0
0 0 1 0 1
0 1 0 0 1
0 0 1 0 0
0 0 0 1 0
0 1 0 1 1
0 0 1 1 1
0 1 1 1 0
0 0 0 1 1
0 1 0 1 0
0 0 1 1 0
0 1 1 1 1
0 1 1 0 1
0 1 0 0 0
0 1 1 0 0
0 0 0 0 1
now i want to take every last 4 bits it each row and convert it into an integer

n = 4; %// number of bits you want
result = m(:,end-n+1:end) * pow2(n-1:-1:0).'; %'// matrix multiplication
Anyway, it would be easier to use mod on x8 directly, without the intermediate step of m:
result = mod(x8(:), 2^n);
In your example:
result =
0
5
9
4
2
11
7
14
3
10
6
15
13
8
12
1

This could be another approach -
n = 4; %%// number of bits you want
out = bin2dec(num2str(m(:,end-n+1:end)))
Output -
out =
0
5
9
4
2
11
7
14
3
10
6
15
13
8
12
1

read data and save it in a single matrix

i have below .dat file, i want matlab reads data in the 'REQUESTS/DURATIONS:' part and save them in a single matrix in size (32,7). i don't know which function to use ,i don't know how to do it. please help me.
file with basedata : j30_17.bas
initial value random generator: 79602564
projects : 1
jobs (incl. supersource/sink ): 32
horizon : 141
RESOURCES
- renewable : 4 R
- nonrenewable : 0 N
- doubly constrained : 0 D
REQUESTS/DURATIONS:
jobnr. mode duration R 1 R 2 R 3 R 4
------------------------------------------------------------------------
1 1 0 0 0 0 0
2 1 1 0 0 0 5
3 1 1 0 3 0 0
4 1 1 8 0 0 0
5 1 7 0 0 2 0
6 1 6 0 0 0 3
7 1 4 1 0 0 0
8 1 5 0 0 10 0
9 1 8 0 0 3 0
10 1 7 0 0 0 1
11 1 8 9 0 0 0
12 1 1 7 0 0 0
13 1 2 0 3 0 0
14 1 3 0 0 0 6
15 1 10 0 7 0 0
16 1 10 3 0 0 0
17 1 2 0 0 3 0
18 1 10 0 0 4 0
19 1 1 0 0 0 3
20 1 1 0 0 7 0
21 1 7 0 2 0 0
22 1 9 0 0 0 10
23 1 9 0 0 7 0
24 1 4 0 4 0 0
25 1 4 0 3 0 0
26 1 1 0 0 4 0
27 1 1 9 0 0 0
28 1 8 0 0 0 9
29 1 1 0 0 0 1
30 1 2 0 8 0 0
31 1 7 0 4 0 0
32 1 0 0 0 0 0
************************************************************************
RESOURCEAVAILABILITIES:
R 1 R 2 R 3 R 4
10 8 13 12
************************************************************************

If you skip the header, textscan() will stop reading the file once the actual type of data does not correspond to the one specified in format, i.e. when all those asterisks begin:
fid = fopen('C:\...\test.txt');
data = textscan(fid, '%f%f%f%f%f%f%f','HeaderLines',15);
fclose(fid);

I'm not sure about older versions, but 2013a can import text files by right clicking a file under the "Current Folder" panel and selecting "Import Data...". The import wizard will open up and allow you to select the range of data to import. Select the matrix option, and click "Import Selection."
To save your matrix, just use the save command.
This approach works well for single files that you just need to read quickly, but not for a large repetetive task.

How to get the unique slices of a matrix?

In matlab, if you have a matrix A you can find the matrix B containing all of the unique rows of A as follows:
B = unique(A,'rows');
What I have is a 3d matrix, with rows and columns as the first two dimensions, and one additional dimension ('slices').
How can I get the 3d matrix containing all the unique slices in a matrix A? Here's an example of the kind of functionality I want:
>> A % print out A
A(:,:,1) =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
A(:,:,2) =
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
A(:,:,3) =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
A(:,:,4) =
0 0 0 1
0 0 1 0
0 1 0 0
1 0 0 0
>> unique(A,'slices'); % get unique slices
A(:,:,1) =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
A(:,:,2) =
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
A(:,:,3) =
0 0 0 1
0 0 1 0
0 1 0 0
1 0 0 0

I would begin by reshaping A so each slice becomes a row (with the reshape command). Then use unique(A, 'rows'). Finally, reshape the unique rows back to the same shape the slices.
For example:
% transforming so each row is a slice in row form
reshaped_A = reshape(A, [], size(A, 3))';
% getting unique rows
unique_rows = unique(reshaped_A, 'rows');
% reshaping back
unique_slices = reshape(unique_rows', size(A, 1), size(A, 2), []);
Or all in one line:
reshape(unique(reshape(A, [], size(A, 3))', 'rows')', size(A, 1), size(A, 2), [])
I haven't checked this above code so use with caution! But it should give the idea.
EDIT
Here it is working on your data (also fixed little bug in above code):
>> reshaped_A = reshape(A, [], size(A, 3))'
reshaped_A =
Columns 1 through 11
16 5 9 4 2 11 7 14 3 10 6
1 0 0 0 0 1 0 0 0 0 1
16 5 9 4 2 11 7 14 3 10 6
0 0 0 1 0 0 1 0 0 1 0
Columns 12 through 16
15 13 8 12 1
0 0 0 0 1
15 13 8 12 1
0 1 0 0 0
Each of these ^^ rows is one of the original slices
>> unique_rows = unique(reshaped_A, 'rows')
unique_rows =
Columns 1 through 11
0 0 0 1 0 0 1 0 0 1 0
1 0 0 0 0 1 0 0 0 0 1
16 5 9 4 2 11 7 14 3 10 6
Columns 12 through 16
0 1 0 0 0
0 0 0 0 1
15 13 8 12 1
These ^^ are the unique slices, but in the wrong shape.
>> unique_slices = reshape(unique_rows', size(A, 1), size(A, 2), [])
unique_slices(:,:,1) =
0 0 0 1
0 0 1 0
0 1 0 0
1 0 0 0
unique_slices(:,:,2) =
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
unique_slices(:,:,3) =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1

A very simple and scalable solution would be:
A = cat(3, [16 2 3 13;5 11 10 8;9 7 6 12;4 14 15 1], [1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1], [16 2 3 13;5 11 10 8;9 7 6 12;4 14 15 1], [0 0 0 1;0 0 1 0;0 1 0 0;1 0 0 0])
[n,m,p] = size(A);
a = reshape(A,n,[],1);
b = reshape(a(:),n*m,[])';
c = unique(b,'rows', 'stable')'; %If the 'stable' option is supported by your version.
%If the 'stable' option is not supported, but it's still required, use the index vector option, as required.
%i.e.,
%[c,I,J] = unique(b,'rows');
unique_A = reshape(c,n,m,[])
Results:
A(:,:,1) =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
A(:,:,2) =
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
A(:,:,3) =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
A(:,:,4) =
0 0 0 1
0 0 1 0
0 1 0 0
1 0 0 0
unique_A(:,:,1) =
0 0 0 1
0 0 1 0
0 1 0 0
1 0 0 0
unique_A(:,:,2) =
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
unique_A(:,:,3) =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
Source: How to find unique pages in a 3d matrix?

Value comparison of matrix elements in MATLAB

Say I have a 256 by 256 matrix. I would like to replace any values that are 'greater' or 'equal' to 10 with 1 and make the rest 0 i.e. (values < 10).
For example,
2 3 6 15 24 32 1 7 39 10 ....
1 5 7 11 19 10 20 28 9 ........
10 24 6 29 10 25 32 10 ..........
.................................
.................................
and I want the output to be:
0 0 0 1 1 1 0 0 1 1 ............
0 0 0 1 1 1 1 1 0 ..............
1 1 0 1 1 1 1 1 ................
................................
................................
How can I do it?

Example:
a = [3 2 6 6 ;
7 5 3 7 ;
7 10 8 9 ;
2 4 3 10];
b = ( a > 5 )
b =
0 0 1 1
1 0 0 1
1 1 1 1
0 0 0 1