Can I add new column (calculated from first column) to a text file ?

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ND 2016-2-24

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评论： Star Strider 2016-3-5

B.txt

Dear all, Please I have a text file has one column and many rows. I need to add new column which is calculated from the first column (the difference between the new set of rows and old set of rows which means the change in the first column. for example, the set of rows below consists from three rows each ( the first zeros should be for both columns).I need to apply this for the text file attached.

0 0

1 (1-0)

3 (3-0)

6 (6-0)

2 (2-1)

5 (5-3)

8 (8-6)

Many thanks

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Star Strider 2016-2-24

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https://ww2.mathworks.cn/matlabcentral/answers/269837-can-i-add-new-column-calculated-from-first-column-to-a-text-file#answer_211087

在 MATLAB Online 中打开

This seems to do what you want:

B = load('ND B.txt', '-ascii');
New_Col = [B(4:end) - B(1:end-3); zeros(3,1)];
New_B = [B New_Col];

The last 3 rows of ‘New_Column’ I set to zero to make it possible to concatenate it with the existing ‘B’. You may want to append them to the beginning instead, or set them to NaN. The point is the columns have to have equal length to concatenate them.

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ND 2016-3-5

编辑：ND 2016-3-5

Please now I want to do summation of column one and two (which is created) and write the column one and the sum in a new text file , so the result would be a text file with only two columns.

Thanks