Look up a value in another array

Question

Aaron 2013-11-12

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/105753-look-up-a-value-in-another-array

评论： Aaron 2013-11-13

I have one array which lists the max values for column of column B for each unique item in column A as follows:

'888888888888888888880001'  -40
'888888888888888888880002'  -47

I have the following array and I would like to find the column A and column B that match with the first row in the above array, and create a new array which adds the column C value for: '888888888888888888880001' -40 to the array. Then do the same thing for the second row in the table above and add it to the same array.

'888888888888888888880001'  -66  9
'888888888888888888880001'  -52  10
'888888888888888888880001'  -47  20
'888888888888888888880001'  -56  26
'888888888888888888880001'  -47  38
'888888888888888888880001'  -51  42
'888888888888888888880001'  -40  47
'888888888888888888880001'  -40  54
'888888888888888888880002'  -50  44
'888888888888888888880002'  -47  57

The result of this should be an array of 2 rows:

'888888888888888888880001'  -40  47
'888888888888888888880002'  -47  57

There are two places that have -40 and I just need it to have either of those values in the final array, but not both.

Any help would be greatly appreciated. Thanks.

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Answer 1

Andrei Bobrov 2013-11-12

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/105753-look-up-a-value-in-another-array#answer_114941

编辑：Andrei Bobrov 2013-11-12

在 MATLAB Online 中打开

EDIT

d1 = [data(:,1), cellfun(@num2str,data(:,2),'un',0)];
a1 = [A(:,1),cellfun(@num2str,A(:,2),'un',0)];
[lk,i2] = ismember(data(:,1),A(:,1));
d1 = [i2(lk) cell2mat(data(lk,2:3))];
a1 = [(1:size(A,1))', cell2mat(A(:,2))];
[lc2,ii2] = ismember(d1(:,1:2),a1,'rows');
data1 = data(lc2,:);
% corrected below
idx = accumarray(ii2(lc2),(1:size(d1(lc2,:),1))',[],@(x)x(randi(numel(x)))); 
out = data1(idx,:);

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Aaron 2013-11-12

Thank you very much! It was very helpful. If you wouldn't mind, could you look at the main question that I had for this data. I asked the question at the following link:

http://www.mathworks.com/matlabcentral/answers/105879-how-to-remove-unwanted-values-from-an-array

It is the last thing I have to do with this data and would help me out a lot.

Aaron 2013-11-13

And I made it look like a long question but it is really the same question as the one I just asked on this one, only it involves using the standard deviation to remove unwanted rows

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