How can I delete an entire row/element of a matrix/array and also delete the same row/element from another matrix/array?

"rawData, "TDT1," and "TDT2" are 1-D arrays/columns of numbers of identical length.

Each array represents a different parameter. The first element of each array represents a measurement taken at a particular time. The second element of each array represents a measurement taken at a new time, and so on.

My problem is that there can be elements in each array equal to "9999," which means that a measurement failed to happen.

• I need to delete elements where the value is "9999."
• Then I also need to delete the same elements/rows from the other two arrays/columns.
• In the end, I need the three arrays to have the same length and no "9999" values.

Does anyone know how I can do this? I have Matlab 2016b. I have so far managed the below, but there are key steps missing.

rawData(rawData   == 9999) = nan; TDT1(TDT1   == 9999) = nan; TDT2(TDT2 == 9999) = nan; % Here I turn the number "999" into "nan" in all three arrays.
% I don't know how to delete a "nan" element from one array and also delete the same element from the other two arrays.

Thank you for any help

Answer 1

[Adam Danz]

Since the column vectors should be the same length, I recommend you combine them into a matrix (shown below) or a table.

m = [columnVector1, columnVector2, columnVector3]; 

Then compute which rows have 9999 values.

removeRowIdx = any(m==9999,2); 

Then delete those rows

m(removeRowIdx,:) = []; 

or replace with NaN values

m(removeRowIdx,:) = NaN; 

If you decide to keep the column vector variables separate, you can use the same approach,

removeRowIdx = columnVector1==9999 | columnVector2==9999 | columnVector3==9999;
columnVector1(removeRowIdx) = [];  % or = NaN
columnVector2(removeRowIdx) = [];  % or = NaN 
columnVector3(removeRowIdx) = [];  % or = NaN

[Ann St]

@Adam Danz, thank you very much for taking time to help. I will try it out. It looks like "removeRowIdx = any(m==9999,2)" is the key step. Thank you!

[Adam Danz]

Indeed. Indexing is critical in Matlab.

It would behove you to take a moment to master it.

https://www.mathworks.com/company/newsletters/articles/matrix-indexing-in-matlab.html

This answer uses logical indexing. See that section within the link above.

[Ann St]

Thank you. That is helpful.

[Adam Danz]

Glad I could help.

[Nevil Maloba]

Can you put this into a function

[Adam Danz]

Yes and I'd be happy to help you do the same. Give it a shot and share what you've got if you get stuck.