MATLAB: Retreive data from a website

app designerMATLABMATLAB Web App Serverretreive data from a websiteweb

Hi, I am looking for a way to retreave multiple data from a website and store them in array in an effecient way, this is my code:

% Get the html for the webpage
html = webread("https://www.digikey.com/products/en/fans-thermal-management/thermal-heat-sinks/219");
% find the start and end of the data and remove the rest
iStart = strfind(html, "Thermal Resistance @ Forced Air Flow");
iStart = iStart(1);
iEnd = strfind(html, "Thermal Resistance @ Natural");
iEnd = iEnd(1);
html = html(iStart:iEnd);
% get the indexes of the start and finish of the data points
iStart = strfind(html, "<option value") +23;
iEnd = strfind(html, "</option")-1;
% pre-allocate results
results = strings(numel(iStart), 1);
% write and clean up results
for i = 1:numel(results)
    
    results(i) = string(html(iStart(i):iEnd(i)));
    results(i) = strrep(results(i), " ", "");
    results(i) = strip(results(i));
    
end

Is there a better and simpler solution then this one ?

Best Answer

I suggest you use regexp() with "named" tokens.

https://www.mathworks.com/matlabcentral/answers/66657-regular-expressions-help-with-html-source-code#answer_78272

https://www.mathworks.com/matlabcentral/answers/362214-regexp-to-filter-file-names

Related Solutions

MATLAB: Harvest data from a website

There are admittedly more glamourous ways of doing this, but this works

% Get the html for the webpage
html = webread("https://www.digikey.com/products/en/fans-thermal-management/thermal-heat-sinks/219");
% find the start and end of the data and remove the rest
iStart = strfind(html, "Thermal Resistance @ Forced Air Flow");
iStart = iStart(1);
iEnd = strfind(html, "Thermal Resistance @ Natural");
iEnd = iEnd(1);
html = html(iStart:iEnd);
% get the indexes of the start and finish of the data points
iStart = strfind(html, "<option value") +23;
iEnd = strfind(html, "</option")-1;
% pre-allocate results
results = strings(numel(iStart), 1);
% write and clean up results
for i = 1:numel(results)
    
    results(i) = string(html(iStart(i):iEnd(i)));
    results(i) = strrep(results(i), " ", "");
    results(i) = strip(results(i));
    
end

MATLAB: Negative thermal resistance in SimScape

When you check the source code of the Thermal Resistance block, it is indeed hard-coded that the thermal resistance is larger or equal than zero.

component resistance < foundation.thermal.branch
% Thermal Resistance
% This block represents a generic resistance in a thermal network. The heat
% flow rate is proportional to the temperature difference and inversely
% proportional to the resistance.
% Copyright 2016 The MathWorks, Inc.
parameters
    resistance = {1, 'K/W'}; % Thermal resistance
end
equations
    assert(resistance >= 0)
    if isfinite(resistance)
        T == resistance * Q;
    else
        Q == 0;
    end
end
end

Unfortunately, you cannot simply change that line of code in the standard Simscape library block.

You may want to investigate creating a custom Simscape block/library.

https://nl.mathworks.com/help/physmod/simscape/lang/create-a-custom-block-library.html

https://nl.mathworks.com/help/physmod/simscape/lang/creating-custom-components.html

I have not done this myself but I believe this is your only possibility of solving the issue.

Best Answer

Related Solutions

MATLAB: Harvest data from a website

MATLAB: Negative thermal resistance in SimScape

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