I want to get the mean of cells in column 4 based on the column 1 value.

Column 1 is numbers 259:374 and could be converted to datetime if easier. It contains decimals for the hours and minutes.

I want to create a mean of all the corresponding values in column 4, from to that specific day,(in column 1) eg 259.00 to 259.99 and do this for every day cycling through to 374.

Ive tried creating a loop but i honestly have no idea where to start, any help would be appreciated.

Answer 1

[David Hill]

m=floor(yourMatrix(:,1));
M=259:374;
for k=1:length(M)
   n(k)=mean(yourMatrix(m==M(k),4));
end

[Leah Davis]

Thank you!

Answer 2

[Image Analyst]

Try splitapply(). It's meant for this. You could probably also use groupsummary() or grpstats().

% Create random data:
column4 = sort(259 + (374-259) * rand(1000, 1))
% Group into groups that have the same value to the left of the decimal point.
groups = findgroups(floor(column4))
% Take the mean of each group.
means = splitapply(@mean, column4, groups)