How to select cell values and cell positions from a matrix?

Hi,

I have a set of six month daily data (attached) in matrix (A) (31 x 6 size).

I used [cell_value, cell_position] = min(A,[],1) to find minimum value (cell value) and corresponding cell position in each column of A. I got two metrices:

1. cell_value (1 x 6);
2. cell_position (1 x 6);

I want two more metrices, "new_cell_value" and "new_cell_positions" such that,

3. new_cell_value - should have all the values less than 1.5*cell_value (row size of this matrix is unknown but has 6 columns), and

4. new_cell_positions of new_cell_value (row size of this matrix is unknown but has 6 columns).

The data is attached. Please help me to solve this.

Thanks in advance.

[Stephen23]

What have you tried so far?

[Parthu P]

Thank you for response.

I tried

[cell_value, cell_position] = min(A,[],1) to find minimum value (cell value) and corresponding cell position in each column of A - it worked very well

I then tried

B = find(A >== 1.15.*cell_value(:,6));

This doesn't give any error but it reads intended values incorrectly (in between A and 1.15.*cell_value). I need all values from A less than "1.15.*cell_value".

Answer 1

[Suleman ZP]

You find mininum cell value and position with this line of code.

[cell_value, cell_position] = min(A,[],1);

and its results 1 row with 6 columns like this.

cell_value =

   90.8900   71.9900  136.0800  120.4500  115.6900  121.9400


cell_position =

    13     1    22    25    28    29

Now using below code we can found all values less than 1.15.*cell_value in each columns.

new_cell_positions =  zeros(size(A));
new_cell_values =  zeros(size(A));
B = A < 1.15.*cell_value;
for i = 1:6
   loca = find(B(:,i) == 1);
   new_cell_positions(1:length(loca),i) = loca;
   new_cell_values(1:length(loca),i) = A(loca,i);
end

this results in random number of rows but fix 6 columns.

new_cell_values =

   91.5800   71.9900  154.8600  135.8900  124.0500  140.0400
   90.8900         0  150.4500  132.4300  122.9100  138.4500
   92.0800         0  153.3600  127.5200  116.3900  138.1300
   99.4600         0  155.6300  123.2600  115.6900  137.9900
         0         0  155.6900  120.4500  116.6400  135.8200
         0         0  152.6400  120.9000  115.8600  137.0000
         0         0  145.3900  121.3700         0  132.1700
         0         0  151.4300  123.2700         0  127.9400
         0         0  149.5000  123.8800         0  126.9800
         0         0  136.6300  124.5200         0  127.9400
         0         0  140.7500         0         0  129.0600
         0         0  146.2000         0         0  131.1200
         0         0  154.8700         0         0  129.5800
         0         0  136.0800         0         0  126.6600
         0         0  141.1900         0         0  125.1200
         0         0  153.2900         0         0  121.9400
         0         0         0         0         0  121.9700
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0
         0         0         0         0         0         0

new_cell_positions =

    12     1     1    21    25     1
    13     0     2    22    26     2
    14     0     3    23    27     3
    31     0     4    24    28     4
     0     0     5    25    29     5
     0     0     6    26    30    19
     0     0     7    27     0    20
     0     0     8    28     0    21
     0     0    11    29     0    22
     0     0    12    30     0    23
     0     0    13     0     0    24
     0     0    14     0     0    25
     0     0    15     0     0    26
     0     0    22     0     0    27
     0     0    23     0     0    28
     0     0    30     0     0    29
     0     0     0     0     0    30
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0

[Parthu P]

Thank you very much for the help.

It works well but there is a small problem with

B = A < 1.15.*cell_value;

It asks dimensions for "cell_value" to run.

When I put cell_value (:,6) or cell_value (:,1). It read cell_value in either 6th or 1st column and apply it to all the columns. How do i put right dimensions for "cell_value (. . . . . )", so that it reads correct 1.15.*cell_value for individual columns for large size metrix?

I use Matlab R2016a. Is dimension error related to this?

Thanks in advance.

[Suleman ZP]

Well I am using MATLAB 2019a.

here I updated the code.

[cell_value, cell_position] = min(A,[],1);
new_cell_positions =  zeros(size(A));
new_cell_values =  zeros(size(A));
for i = 1:6
   B = A(:,i) < 1.15.*cell_value(i);
   loca = find(B == 1);
   new_cell_positions(1:length(loca),i) = loca;
   new_cell_values(1:length(loca),i) = A(loca,i);
end

[Parthu P]

Hi Suleman,

Thanks very much for response. I really appreciate your time and effort.

Unfortunately, updated code makes new_cell_positions, new_cell_values, and B all-zero.

Rather previous code worked well but I had difficulty with "B = A < 1.15.*cell_value " in putting right dimensions.

Please help me with dimensions next to "cell_value" in "B = A < 1.15.*cell_value;" in the previous code.

Thank you in advance.

[Suleman ZP]

Can you please share the out of this line. So I can compare and understant the issue. B = A < 1.15.*cell_value;