How to use multiple set of variables in a calculation and store the results?

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LoroEE 2022-4-5

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评论： LoroEE 2022-4-7

I have multiple sets of variables that need to be used in a calculation. I have to select each one manually by uncommenting the one I need. My code looks like this:

%% Set 1 % This is the set currently being used.

cable = 'Merlin';

cct = 5.673133;

diametro = 0.0173736;

Res_50 = 0.18875;

RMG = 0.00676656;

%% Set 2 % The rest of them are all commented

% cable = 'Osprey';

% cct = 8.286702;

% diametro = 0.0223266;

% Res_50 = 0.114543195;

% RMG = 0.00865632;

%% Set 3

% cable = 'Ortolan';

% cct = 12.10432;

% diametro = 0.0308102;

% Res_50 = 0.062834058;

% RMG = 0.01225296;

%% Set 4 and so on...

% Huge calculation happens here.

% Results from the current set are displayed.

This is obviously very inneficient. I want my program to run through each one of the sets and then store the results in an organized manner on a matrix or table, like so:

Set |   Name    |   Important number    |   Some other number   | etc...
 1  |   Merlin  |       123             |       456             |
 

I'm sure this is a common problem but I couldn't find an adequate answer since I'm not well versed in programming lingo.

Thank you!

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Answer 1

Stephen23 2022-4-6

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https://ww2.mathworks.cn/matlabcentral/answers/1689435-how-to-use-multiple-set-of-variables-in-a-calculation-and-store-the-results#answer_935875

编辑：Stephen23 2022-4-6

在 MATLAB Online 中打开

data.txt

Your current approach should be avoided: in general it is not considered good code design to store lots of data in executable code.

The best solution would be to save the data in a data file and import that. For example I moved your data to a text file (attached):

T = readtable('data.txt')
T = 3×5 table
       cable        cct      diametro     Res_50        RMG   
    ___________    ______    ________    ________    _________

    {'Merlin' }    5.6731    0.017374     0.18875    0.0067666
    {'Osprey' }    8.2867    0.022327     0.11454    0.0086563
    {'Ortolan'}    12.104     0.03081    0.062834     0.012253

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html

As an alternative you could store the data in any kind of iterable array (which could be a container array). For example, using a structure array make it trivial to loop over your data:

%% Set 1 % This is the set currently being used.

S(1).cable = 'Merlin';

S(1).cct = 5.673133;

S(1).diametro = 0.0173736;

S(1).Res_50 = 0.18875;

S(1).RMG = 0.00676656;

%% Set 2 % The rest of them are all commented

S(2).cable = 'Osprey';

S(2).cct = 8.286702;

S(2).diametro = 0.0223266;

S(2).Res_50 = 0.114543195;

S(2).RMG = 0.00865632;

%% Set 3

S(3).cable = 'Ortolan';

S(3).cct = 12.10432;

S(3).diametro = 0.0308102;

S(3).Res_50 = 0.062834058;

S(3).RMG = 0.01225296;

%% Set 4 and so on...

..

for k = 1:numel(S)

S(k).cable

S(k).cct

end

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

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Stephen23 2022-4-7

"So may I ask how would you iterate through this table, perform an operation with each number variable (e.g., n*2) and output the results to another file?"

Either use a loop and indexing or use one of MATLAB's routines for operating on the rows/columns/groups of tables.

Save the resulting data to an array/table, then save that array/table using an appropriate function.

That is about a specific as I can answer your question lacking in any details. Basically what you asked is equivalent to "how do I use MATLAB", which if you want a complete answer covering all possible data processing (because you did not give any specific details) would require me to copy most of the MATLAB documentation into this comment.

I also have no idea what your background is or what experience you have: do you know what a loop is? Do you know how to use indexing? Are you proficient in Haskell?

These tutorials will teach you fundemental concepts that you will need know to use MATLAB: https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

LoroEE 2022-4-7

You are right, I'll accept your answer and think about a more specific question.

I'm an engineering student, my programming knowledge is all over the place and I still consider myself a begginer. I do know what a loop and indexing is. I also know what needs to be done, the problem is telling Matlab to do it, particularly the interaction between the loops and indexing and file output.

I could probably figure out a very idiotic way of doing this, but it will take days and I rather just ask. Documentation is really obtuse and I feel the beginner examples don't really cut it anymore.

Anyways, just getting this out there. I'm still in the process of figuring out how to ask (and find) good questions.

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