Subtract mean from each table by columns

Hello,

Assume we have the following table

t = array2table([rand(10,1),rand(10,1),rand(10,1)],'VariableNames',{'feat_1', 'feat_2','feat_3'});

t =

10×3 table

feat_1 feat_2 feat_3

________ ________ _________

0.12991 0.60198 0.82582

0.56882 0.26297 0.53834

0.46939 0.65408 0.99613

0.011902 0.68921 0.078176

0.33712 0.74815 0.44268

0.16218 0.45054 0.10665

0.79428 0.083821 0.9619

0.31122 0.22898 0.0046342

0.52853 0.91334 0.77491

0.16565 0.15238 0.8173

I can get the mean and standard deviation for each solumn using

meanArray = mean(table2array(t,1));
stdArray = std(table2array(t,1));

meanArray =

0.3479 0.4785 0.5547

stdArray =

0.2415 0.2836 0.3793

Is there any vector way to caclulate (element - mean / std) on every element in table without loop and keep the table? Thanks

I know normalize could standardize data but I need to make it in code.

[madhan ravi]

Expected output?

Answer 1

[Image Analyst]

Try this:

t = array2table([rand(10,1),rand(10,1),rand(10,1)],'VariableNames',{'feat_1', 'feat_2','feat_3'})
m = table2array(t);
meanArray = mean(m)
stdArray = std(m)
z = (m - meanArray) ./ stdArray % a matrix
zt = array2table(z, 'VariableNames',{'feat_1', 'feat_2','feat_3'}) % a table

[wbadry]

Thank you so much.

Answer 2

[wbadry]

Hello,

I came by another solution using bsxfun

Here is a complete example based on my question

% Generate random columns for the example (10 by 3)
t = array2table([rand(10,1),rand(10,1),rand(10,1)],'VariableNames',...
    {'feat_1', 'feat_2','feat_3'});

% Subtract from the mean vector (3 by 1)
t1 = bsxfun(@minus, mean(table2array(t)),table2array(t));

% Divide by stadard deviation vector (3 by 1) using right array division
t2 = bsxfun(@rdivide,t1,std(table2array(t)));

% Create the standardized table
t = array2table(t2,'VariableNames',{'feat_1', 'feat_2','feat_3'});

% Check mean and std of feat_1
feat_1_mu = mean(t.feat_1)
feat_1_sig = std(t.feat_1)

feat_1_mu =

0

feat_1_sig =

1

[Image Analyst]

Yeah, you can do it that way if you want. I always find their *xfun() functions very cryptic and confusing than the regular math symbols. Plus you always have to find or figure out what the operations are. I mean, who would know, off the top of their head, that if you want to divide something you use @rdivide instead of the slash symbol /, or @minus instead of -. And it gets even more confusing for other operations.