MATLAB: Find average of multiples lines

averages

Hi All,

Having more trouble than I should finding the average line from 7 records. Each record is basically [T, (a-b)], where T is a common time interval (0:0.1:30) and (a-b) is the difference between two data sets (a-b, a-c, a-d, etc.).

I've designated each "difference" as such: diff, diff2, diff3, diff4, diff5, diff6, diff7. I am easily able to plot all of these records on the same plot. However, each method to find the mean of these lines fails. SO far, I have used mean([diff diff2, etc.],7). How do I go about finding the average for each common time point and then plot that?

Thanks.

Best Answer

Regarding the follow-up question found in the comments (NaN affecting the mean):

Use the 'omitnan' flag of the mean function (R2015a and newer):

%%%I wouldn't use "diff" as a variable name - it's a function
avg = mean([diff1, diff2, diff3, diff4, diff5, diff6, diff7],2,'omitnan');

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MATLAB: Please help me understand whether I have set up a loop and performed an RMSE (Root Mean Square Error) calculation correctly

You could do something like this.

I just made up some numbers to try the code.

Also, obviously variable names like columnOfData are not very meaningful and I wouldn't recommend them but I didn't want to depart to far from your starting point.

I removed some of the ./ and just used / where the operation involved a vector and a scalar so element by element calculations were not needed. Would work with ./ but makes it less clear what you are doing. I also defined x separately from the index in the loop, in case you wanted to use other x values and also so tha you could have an index for recording the RMSE values.

With some more work, you could probably fully vectorize this (eliminate the loop) but at least this should get you started.

% define constants
a = 2.2
b = 3.4
c = 8.1
d = 10.4
e = 0.6
f = 22.4
% define measured value 
avgW = [8;7.2;44;3.12] 
% define column of data
columnOfData = [3;9;8.3;2]
% number of elements in avgW (and column of data)
g = length(avgW)
x = 1:10000;
for k = 1:10000
    wCalc = ( ( a ./ ( ( columnOfData / x(k) ) - b ) ) - c - d - e ) * f; % a vector
    RMSE(k) = sqrt( sum( ( wCalc - avgW).^2) / g );
end
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MATLAB: Correlation between two row matrices

Like that, each value of "a" is correlated to each value of "b", but applying the formula of the correlation, the correlation of two single numbers is NaN. To compute the correlation correctly, traspose the input vectors

result  = corr(a', b');

Best Answer

Related Solutions

MATLAB: Please help me understand whether I have set up a loop and performed an RMSE (Root Mean Square Error) calculation correctly

MATLAB: Correlation between two row matrices

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