How to add a new row in matrix

A = [
1  3  270  395
1  2  1590  1650
1  5  1650  1710
2  3  260  310
2  2  1550  1600
2  7  1600  1650
2  1  1650  1700
3  3  245  405
3  1  405  510
3  7  1025  1075
3  3  1075  1340
3  3  1340  1685
4  3  240  380
4  5  1610  1650
4  2  1650  1680
];

For every unique ID (first column in matrix A), the following procedure should be followed:

The max value in the forth column should be identified. If it is greater than 1680, then we need to adjust the matrix. First, the max value in the matrix should be replaced by 1680. Second, a new row should be added to matrix (at first row) and for its values: 2_1: the ID (first column) should be repeated as current ID, 2_2: the second column value should be repeated as second column value for identified max value, 2_3: the third column value should be 240, 2_4: the forth column value should be same as value in the third column (first row before adjusting the matrix).

e.g. for ID = 1:

Input:

    1  3  270  395
    1  2  1590  1650
    1  5  1650  1710

Output (after applying steps):

    1  3  240  270
    1  3  270  395
    1  2  1590  1650
    1  5  1650  1680

Output matrix for all IDs:

out = [
1  3  240  270
1  3  270  395
1  2  1590  1650
1  5  1650  1680
2  3  240  260
2  3  260  310
2  2  1550  1600
2  7  1600  1650
2  1  1650  1680
3  3  240  245
3  3  245  405
3  1  405  510
3  7  1025  1075
3  3  1075  1340
3  3  1340  1680
4  3  240  380
4  5  1610  1650
4  2  1650  1680
];

Answer 1

[Image Analyst]

I don't understand your complicated rules. I got as far as determining the max for each group (the ID # in col 1) and then subtracting 1680 from it. This code will do that:

groupMaxes = grpstats(A(:, 5), A(:, 1), 'max')
groupDeltas = groupMaxes - 1680

You get

groupMaxes =
        1710
        1700
        1685
        1680
groupDeltas =
    30
    20
     5
     0

but I have no idea what to do after that because the explanation and example result are so confusing (to me). I mean you say "one new column should be added" then you say "The second column value should be repeated for the new added row." _What* column value should be repeated? What new added row? Did you say to add a row?

And I don't understand what you mean when you say "the fifth column ended" or "the third row is ended". What does it mean for a row or column to be "ended"???

[Tiffan]

@Image Analyst, for better clarity, I've edited the question. Thanks!