Calculation with strcmp with variable values

Question

Max Bornemann 2019-4-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/456267-calculation-with-strcmp-with-variable-values

评论： Max Bornemann 2019-4-16

采纳的回答： A. Sawas

在 MATLAB Online 中打开

Hello,

I have the following three tables:

Tab1=table('Size',[9 3],'VariableTypes',{'cell','double','double'},'VariableNames',{'Description','Year','Value'});
Tab1.Description(:)={'Gas','Gas','Gas','Pellets','Pellets','Pellets','Oil','Oil','Oil'};
Tab1.Year(:)=[2015,2020,2025,2015,2020,2025,2015,2020,2025];
Tab1.Value(:)=[5,10,17,7,25,75,23,47,54];
Tab2=table('Size',[6 3],'VariableTypes',{'cell','double','double'},'VariableNames',{'Description','Year','Value'});
Tab2.Description(:)={'Gas','Gas','Gas','Oil','Oil','Oil'};
Tab2.Year(:)=[2015,2020,2025,2015,2020,2025];
Tab3=table('Size',[3 2],'VariableTypes',{'double','double'},'VariableNames',{'Year','Value'});
Tab3.Year(:)=[2015,2020,2025];
Tab3.Value(:)=[1002,3007,2001];

I am searching for a way, to simplify the following calculation:

for i=1:3
    Tab2{strcmp(Tab2.Description,'Gas'),'Value'}(i)=Tab1{strcmp(Tab1.Description,'Gas'),'Value'}(i)*Tab3{i,'Value'};
    Tab2{strcmp(Tab2.Description,'Oil'),'Value'}(i)=Tab1{strcmp(Tab1.Description,'Oil'),'Value'}(i)*Tab3{i,'Value'};
end
clear i;

Imagine Tab1 and Tab2 are way bigger and there are way more different Values in the "Description"-column, then the solution above would be inappropriate.

I thought about something like:

for i=1:3
    Tab2{strcmp(Tab2.Description,'X'),'Value'}(i)=Tab1{strcmp(Tab1.Description,'X'),'Value'}(i)*Tab3{i,'Value'};
end
clear i;

where X can have all the different Descriptions from Tab2. But i don´t know how to do it in MATLAB.

I will greatly appreciate any assistance.

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Answer 1

A. Sawas 2019-4-15

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/456267-calculation-with-strcmp-with-variable-values#answer_370624

在 MATLAB Online 中打开

[C,idx1,idx2] = innerjoin(Tab1,Tab2, "LeftKeys",{'Description','Year'},"RightKeys",{'Description','Year'});
[~,idx3] = join(C, Tab3, "Keys","Year");
Tab2.Value(idx2) = Tab1.Value(idx1).*Tab3.Value(idx3);

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A. Sawas 2019-4-15

编辑：A. Sawas 2019-4-15

My pleasure!

I want to add that the steps can be simplified if you are generating Tab2 from Tab1. Hence, in the above solution, the inner join is needed assuming those tables are different but have two common variables.

Max Bornemann 2019-4-16