Need some help setting up a function for elementary data filtering

Hi,

I have imported a data array (Araw) that has a couple thousand rows and 17 columns (50Hz data - each column represents a monitored variable). These are the tasks I am required to perform with Matlab:

• Absolute value all values in column 7
• Remove all rows of data where values in column 8 are >=0
• Absolute value all remaining values in column 8
• Rename the new array "A"

I'm relatively new at programming with Matlab so any help/hints/tips are most appreciated.

Many thanks,

Riccardo

Answer 1

[Oleg Komarov]

 1. abs(A(:,7))

 2. idx = A(:,8)>= 0; A = A(~idx,:);

Last two up to you.

[Riccardo Del Bosco]

Thanks Oleg!

Answer 2

[Honglei Chen]

You can use logical index to do this. For example, to achieve the first task, you can do something like

x = ones(5,4);
x(:,2) = abs(x(:,2))

You can also try the following code and see what happens

x = ones(5,4);
x(3,:) = []

HTH

[Riccardo Del Bosco]

Thanks Honglei, I'll try that out.