How to mean data of second column with respect to the similar element in the first column

Dear All,

I have a data array with two column. The first array is contain repeated values of different order and the second column contain the respective data. I need to mean elements in second column which has same value in the first column. Example of data pic attached hereby. According to the figure i need to mean only values of column two correspond to 0, 0.016667 and so on. Thank you in advance

Answer 1

[Cris LaPierre]

Use groupsummary or grpstats. Group on column A, and set the 'method' to 'mean', and set the datavars to column B.

If you import you data to a table, use this syntax:

• G = groupsummary(T,groupvars,method,datavars)

If your data is in vectors, use this syntax

• B = groupsummary(A,groupvars,method)

Answer 2

[Paul]

Check out splitapply. Applies directly to this problem.

Answer 3

[VBBV]

This is one approach

 D(:,1) = [zeros(6,1); ones(6,1)*0.01667; ones(6,1)*0.05];
 D(:,2) = rand(length(D),1);
 o = unique(D(:,1));
 
 for k = 1:length(o)
     idx = find(D(:,1) == o(k));
     Data(k) = mean(D(idx,2));
 end
 Data

Data = 1×3

0.4640 0.4352 0.4520

Answer 4

[VISHNU]

Dear guys, Thank you for your Answers.

I tried like the following below and it worked well.

[C,ia] = unique(data(:,1));

for n=1:length(ia)-1

meandata(n,1)=mean(data(ia(n):(ia(n+1)-1),2));

end