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Converting a 2d vector to a 4d vector

Asked by Basu Sau on 25 Feb 2019
Latest activity Commented on by Basu Sau on 25 Feb 2019
In a machine learning task, I need a 4d single type data to fed for training. But my data is in a 2d format. Would you please show me how to do this conversion.
Input:
for data of 28th row,
val(28,1)=1.5
val(28,2)=2.7
output:
val(:,:,1,28)=1.5
val(:,:,2,28)=2.7
I m looking for your advice in this regard.
Thanks,

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2 Answers

Answer by ANKUR KUMAR on 25 Feb 2019
 Accepted Answer

Let's take a random data A
A=randi(10,30,2);
Use permute to change into 4D
B=permute(A,[3,4,2,1]);
Now, B(:,:,2,24) and A(24,2) are same.
>> B(:,:,2,24)==A(24,2)
ans =
logical
1

  3 Comments

hi Ankur. would u pls explain the parameters u pass inside permute()?
First input of permute is the data itself.
Second input is in the row matrix which contains the sequence of dimension you wish to put it.
For example, in B, we have stored first the fourth dimension, then the thrid dimension, followed by second and first.
If we write,
B=permute(A,[3,4,1,2]);
then
>> B(:,:,24,2)==A(24,2)
ans =
logical
1
SIMPLE EXAMPLE
>> A=magic(5)
A =
17 24 1 8 15
23 5 7 14 16
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
>> permute (A,[2,1])
ans =
17 23 4 10 11
24 5 6 12 18
1 7 13 19 25
8 14 20 21 2
15 16 22 3 9
Permute simply changes the dimension as per your input in purmute command.
thanks ankur for a such explainatory comment

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Answer by madhan ravi
on 25 Feb 2019

Aternatively:
[m,n]=size(val);
Val=reshape(val.',1,1,n,m)

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