How can I link data from separate arrays?

Question

Matthew Weltevreden 2021-2-26

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评论： dpb 2021-2-27

Suppose you have an array [4 7 9 4 8 3] which represents a list of parameter values within a database. For example ‘4’ is the thickness of a plate which has an associated array containing location and temperature values (5x2 double) [0.55 0.16; 0.60 0.16; 0.65 0.15; 0.7 0.14; 0.75 0.12]. Each of the thickness values has an associated 5x2 array which is unique.

So the question I have is this: Is there a way I can link the location and temperature data arrays with the thickness values so that I can plot all the arrays which correspond to thickness value of ‘4’ without doing this manually?

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dpb 2021-2-26

Be more helpful to us to have information on how the corollary data are stored; generated; etc., ... to have some idea on how they are linked/associated.

Matthew Weltevreden 2021-2-26

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field1 = 'Data1';
field2 = 'Data2';
field3 = 'Data3';
Thickness1 = 19.0;
Thickness2 = 22.0;
Thickness3 = 32.0;
Temp_data1 = [0,-0.05;0.2,-0.13;0.4,0.25;0.6,0.64;0.8,0.56;1,-0.063];
Temp_data2 = [0,0.36;0.2,-0.15;0.4,-0.1;0.6,0.21;0.8,0.47;1,0.35];
Temp_data3 = [0,0.64;0.2,-0.22;0.4,-0.42;0.6,-0.11;0.8,0.28;1,-0.027];
value1={Thickness1,Temp_data1};
value2={Thickness2,Temp_data2};
value3={Thickness3,Temp_data3};
database = struct(field1,value1,field2,value2,field3,value3);
input_thickness = 20;

I've provided some more information to help with the question, assuming the data is part of a struct i would like to extract all the temp data which is larger than a given input thickness in this case 20 (i.e. Temp_data2 & Temp_data3)

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Answer 1

dpb 2021-2-26

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https://ww2.mathworks.cn/matlabcentral/answers/756879-how-can-i-link-data-from-separate-arrays#answer_634294

编辑：dpb 2021-2-26

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Making harder than needs must be --

Thickness=[19.0;22.0;32.0];
Temp_data=cat(3l [0,-0.05;0.2,-0.13;0.4,0.25;0.6,0.64;0.8,0.56;1,-0.063];
                 [0,0.36;0.2,-0.15;0.4,-0.1;0.6,0.21;0.8,0.47;1,0.35];
                 [0,0.64;0.2,-0.22;0.4,-0.42;0.6,-0.11;0.8,0.28;1,-0.027]);
input_thickness = 20;
isWanted=(Thickness>input_thickness);   % logical vector of locations wanted
data=Temp_data(:,:,isWanted);           % return temperature data wanted

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Steven Lord 2021-2-26

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This approach has Thickness and Temp_data in separate variables. If Matthew Weltevreden wants to store the data in a combined variable, one question to ask is which form of "slicing" should be easier.

Thickness=[19.0;22.0;32.0];
Temp_data=cat(3, [0,-0.05;0.2,-0.13;0.4,0.25;0.6,0.64;0.8,0.56;1,-0.063], ...
                 [0,0.36;0.2,-0.15;0.4,-0.1;0.6,0.21;0.8,0.47;1,0.35], ...
                 [0,0.64;0.2,-0.22;0.4,-0.42;0.6,-0.11;0.8,0.28;1,-0.027]);
structContainingArrays = struct('Thickness', Thickness, 'Temperature', Temp_data);
arrayContainingStructs = struct('Thickness', Thickness(1), ...
    'Temperature', Temp_data(:, :, 1));
arrayContainingStructs(2) = struct('Thickness', Thickness(2), ...
    'Temperature', Temp_data(:, :, 2));
arrayContainingStructs(3) = struct('Thickness', Thickness(3), ...
    'Temperature', Temp_data(:, :, 3));
whos
  Name                        Size             Bytes  Class     Attributes

  Temp_data                   6x2x3              288  double              
  Thickness                   3x1                 24  double              
  arrayContainingStructs      1x3               1064  struct              
  structContainingArrays      1x1                648  struct              

Yes, I know I probably could have written those last lines more simply.

structContainingArrays makes it easier to "slice" the data looking at all the Thicknesses or all the Temperatures at once. It's more difficult to use that to get both Thickness and Temperature for one of the parameter values.

structContainingArrays.Thickness
ans = 3×1
    19
    22
    32

arrayContainingStructs slices the data differently. Getting the Thickness and Temperature for one of the parameter values is easier while getting all the Thickness values or all the Temperatures is harder.

arrayContainingStructs(2)
ans = struct with fields:
      Thickness: 22
    Temperature: [6×2 double]

Another way to store this data may be to create a table array.

struct2table(arrayContainingStructs)
ans = 3x2 table
    Thickness    Temperature 
    _________    ____________

       19        {6×2 double}
       22        {6×2 double}
       32        {6×2 double}

Matthew Weltevreden 2021-2-27

在 MATLAB Online 中打开

Thanks for the advice. I was also wondering what could be done if the Temp_data arrays are not identical i.e. if a 8x2 double was also part of the same database such as below?

[0.2,-0.23;0.25,0.029;0.3,0.3;0.35,0.56;0.4,0.78;0.45,0.93;0.5,1.021;0.55,1.02]

dpb 2021-2-27

That would then require something like the table with the 2D arrays a cells; you wouldn't be able to use the 3D array "trick" as the planes have to be the same dimension(*) to do that.

(*) It would require augmenting to the maximum size with NaN or somesuch to do that.

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Answer 2

Hernia Baby 2021-2-26

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The code below is one I assumed from your infomation.

Therefore, it might be different from what you want to do.

As the other members said, you need to give us enough input data.

Thickness = [4 7 9 4 8 3];
% create datas by the number of thickness datas
name = ("parts"+char('A'+(0:length(Thickness)-1'))');
LocTemp(:,:,1) = [0.55 0.16; 0.60 0.16; 0.65 0.15; 0.7 0.14; 0.75 0.12];
for i = 1:length(Thickness)-1
  LocTemp(:,:,i+1) = LocTemp(:,:,i) + 0.01;
end
% seperate data into location and temperature
Location = squeeze(LocTemp(:,1,:))';
Temperature =  squeeze(LocTemp(:,2,:))';
% integration as cell type
for i = 1:length(Thickness)
    C(i,:) = {name(i),Thickness(i),Location(i,:),Temperature(i,:)};
end
% legends
leg = {'name' 'thickness' 'location' 'temperature'};
% convert type
S = cell2struct(C, leg, 2);
% output example
S(1)