for loops and creating new vectors

Question

akk 2019-1-25

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/441538-for-loops-and-creating-new-vectors

编辑： Stephen23 2019-1-26

采纳的回答： Stephen23

Any help with this is appreciated!

I have a matrix(mytable) that is a 128x3 double, mytable(:,1)=CO2, mytable(:,2)=year mytable(:,3)=month

I also have a matrix(k), that is a 12x2 double, k(:,1)=month, k(:,2)=diffCO2

When a value in mytable(:,3) is equal to k(:,1), I would like to take the value at mytable(:,1) - the value at k(:,2) and produce a new mytable(:,4) with the populated values.

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jahanzaib ahmad 2019-1-26

please upload the data file . it will save my time to make data and write code .and thats the best way to get the answer .share ur code coz people like to help with code .

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Answer 1

Stephen23 2019-1-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/441538-for-loops-and-creating-new-vectors#answer_358097

编辑：Stephen23 2019-1-26

在 MATLAB Online 中打开

You don't need any loops, just use ismember:

>> mytable = [111,11,1;222,22,2;444,44,4;666,66,6;999,99,9]
mytable =
    111     11      1
    222     22      2
    444     44      4
    666     66      6
    999     99      9
>> k = [2,2222;4,4444;7,7777;9,9999]
k =
      2   2222
      4   4444
      7   7777
      9   9999
>> [X,Y] = ismember(mytable(:,3),k(:,1));
>> mytable(X,4) = k(Y(X),2)
mytable =
    111     11      1      0
    222     22      2   2222
    444     44      4   4444
    666     66      6      0
    999     99      9   9999