find the lowest value in a selection of data

I have a matrix of data where I am working with columns 5 and 6. I have divided the data into sections based on the values of column 5.

Now for each of the variables S1-S4, I want to find the lowest value of column 6 that occurs in each variable, and save both the values in columns 5 and 6 that correpsond to this and plot the values on a graph.

S1 = T(:,5) >0.13;
S2 = T(:,5)>= 0.115 & T(:,5) <= 0.129;
S3 = T(:,5)>= 0.1 & T(:,5) <= 0.114;
S4 = T(:,5)>= 0.084 & T(:,5) <= 0.09;

[KSSV]

REad about min. This gives you index as well, using this you can get what you want.

[C.G.]

I know I need to use min, but I cant work out how to tell it to look in column 6 of that defined range when that range uses column 5

[Scott MacKenzie]

Your variables S1 through S4 are logical vectors. They contain 1s in positions corresponding to the items of interest in column 5. You can use these variables to retrieve the corresponding minimum values in column 6. As an example, for the logical vector S1, the minumum corresponding value in column 6 is

min(T(S1,6))

[C.G.]

ok i understand that, how would I get the value of column 5 which also equates to this?

Answer 1

[Scott MacKenzie]

[m, idx] = min(T(S1,6)); % minimum value in column 6, as per S1
x = T(idx,5);            % value in column 5 at same location/row

[C.G.]

Thank you that’s great