Keep track of Matrix row indices after deleting some rows

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Nadatimuj 2021-4-18

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评论： Nadatimuj 2021-4-18

Suppose, I have a 10x10 Martix A= magic(10).

Then I delete some rows from it as A([3 5 6],:)=[]. and some columns as A(:,[3 5 6])=[]

Now it's a 7x7 matrix.

I want to keep track of the indices to know which row in the orginal matrix becomes which row in the transformed matrix.

A= magic(10);

A([3 5 6],:)=[];

A(:,[3 5 6])=[];

I want to keep track that previous 4th row is now the 3rd row...previous 7th row is now the 4th row...etc. Any solid way to do that? Please help. Thanks.

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Answer 1

KALYAN ACHARJYA 2021-4-18

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编辑：KALYAN ACHARJYA 2021-4-18

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You can store the A in a temporary variable, and do the modification on temp

temp=A;

Now do the all modification on temp. Result A is original and temp is the modified matrix. Afterwards you can do the comparision between A and temp, like simmilarity

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Nadatimuj 2021-4-18

Hi,

Thanks for your suggestion. I actually seek help for that "comparison" part. I need to save (for further use) a mapping of new indices that can give me the corresponding old index Matrix row

for example, temp(7,:) and modified(4,:) will give me similar row...I need such index mapping. Thanks.

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