How can I extract a specific row of data from each column of a matrix

Hello, Matlabbers.

I have 286x8 matrix (X) where each column of data has a different number of numerical data points followed by NaNs to create a length of 268 for each column. I have identified the last row of numerical data in each column using the command Y = sum(isfinite(X)) which returns a 1x8 row of data identifying the final data point of non-NaN values. What I need to do now is extract the data from each column of X corresponding to each value in Y. Nothing I have tried has worked. Does anyone have any suggestions for how to extract these values?

Thanks, John

Answer 1

[John Harry]

I did some extra digging, and was able to get the data I need using a basic for loop (Not sure why a loop with this structure did not cross my mind earlier!). The loop that did the trick was:

for i = 1:length(Y)

X_Y(i) = X(Y(i),i)

end

Answer 2

[Eamon]

X(Y(1))

should work to get that data point for the first column of X,

X(Y(2))

for the second column of X, etc.

Answer 3

[James Tursa]

X_Y = X(Y + (0:numel(Y)-1)*size(X,1));