Standard deviation, Mean values for each class
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Hello, I have a problem with a code.
First of all I have a .csv file with 2 columns, as I show you in the Image. in the first column the data are split by 0.5 (1,1.5,2).
I would like to find mean values and standard deviation for each of one class, I mean one value of standard deviation and mean value for the data with 1 in , one value of standard deviation for the 1.5 and one value of standard deviation for the 2.
I mean I wanna use the errorbar command.
I think I should use a loop who reads 1st column one by one but I can not make it.
Could anyone help me?
采纳的回答
data = [ 1 1 1.5 1.5 2 2; 10 9 7 6 3.5 8]',;
[dataMean, dataStd] = grpstats(data(:,2), data(:,1), {'mean', 'std'})
If your data are in table format,
Tstats = grpstats(T, 'data1', {'mean','std'});
% ^^^^^ VariableName for column 1
If you don't have Stats & Machine Learning Toolbox,
stats = splitapply(@(x)[mean(x), std(x)], data(:,2), findgroups(data(:,1)));
8 个评论
Ivan Mich
2020-3-24
std is a builtin Matlab function. However, you have a script (m-file) named "std.m" so when you try to use the std() function, Matlab is accessing your std.m script instead.
Solution: rename the std.m file. Avoid naming matlab files after commonly used functions. You may need to rehash your path afterwards using rehash path.
To find your std.m file, execute: which std -all
Ivan Mich
2020-3-24
Check out these errorbar examples. If you have trouble applying them to your data, let me know what the trouble is. https://www.mathworks.com/help/matlab/ref/errorbar.html#bvc1i63-8
Ivan Mich
2020-3-24
the problem is that I would like to plot my final plot like this
but I can't make it. This plot is from an another software.
in x axis there are the values in column 1, y values are in column 2 .
from the command
stats = splitapply(@(x)[mean(x), std(x)], data(:,2), findgroups(data(:,1)));
you suggested are coming out 2 columns each of them has 3 values.
Do you know how to make it?
Adam Danz
2020-3-24
Regarding the errorbar question, it's really easy.
- Use the errorbar function to plot the main line and errorbars
- Add the values from the main line to the error values to produce the dotted lines.
% lower error line
plot(x, y-err)
% upper error line
plot(x, y+err)
Regarding the splitapply output, the rows are the groups (1, 1.5, 2) and the columns are [mean, std].
Adam Danz
2020-3-25
plot(x, y-err)
plot(x, y+err)
1) You should be using the meanvalues insetad of x.
2) err, in your code, is the handle to the error bars. You should be using the stdvals.
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