Obtain rho and pval values from a loop of data measurements

Obtain rho and pha values from a loop of data analysis,

I have created a loop to open multiple spreadsheets from different sources pertaining to collected data measurements (diameter and height) and want to obtain Pearson’s rho and pval values after each iteration for each project in a table.

% Nº of projects

n=20;

% Rango diam boxplots(mm)

rango=5;

for i=1:n

%: Readtable project spreadhseets

if i==1

rawTable = readtable('Project 1,'Sheet','ExportResult');

elseif i==2

rawTable = readtable('Project 2','Sheet','ExportResult');

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else

rawTable = readtable('Project 2','Sheet','ExportResult');

end

x = rawtable.x; %: Column x

y = rawtable.y; %: Column y

% Pearson (preallocating required.%

[rho(i),pval(i)] = corr(x, y, 'type', 'Pearson');

end

The issue that I have is that I have a pop-up message saying that variable ‘I’ changes in size after each iteration and to consider pre-allocating for speed.

I would wish to obtain a n x 2 column (rho and pval) set of data to enable later data analysis without this issue being flagged up in Matlab and to speed the data processing.

Please, note that I have unsuccessfully tried many different combinations looking at support doc and community.

Any help on this will be appreciated.

Thanks.

Cesar

Answer 1

[VBBV]

[rho(i,:),pval(i,:)] = corr(x, y, 'type', 'Pearson');  

[CB]

Hi VBBV,

Thanks for your support, however, I do still get the same pop-up message asking to pre-allocate for speed.

Kind reagrds,

[Simon Chan]

Initialize the variables before the for loop.

rho = zeros(n,1);
rho2 = zeros(n,1);
%.....

[CB]

Hi Simon,

Thank you so much!

Kind regards,

Cesar