sort multiple reference
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Thread: sort multiple reference

  1. #1
    Join Date
    May 2011
    Posts
    1

    sort multiple reference

    Hi,

    I have to sort some matrix by different option. It is not about the method really but something with uncommon options. I explain :
    I have N matrix of the same size. I want to sort the i-th column of the k-th matrix and duplicate the rearrangement to each other columns and matrix.
    Example :

    00 20 05 10 07 06 03 04 10 12
    03 40 08 02 23 | 50 17 01 10 15
    06 30 14 19 33 | 00 18 02 21 34
    39 15 00 11 08 16 07 04 22 40

    should be sort on reference of the 0th matrix with the 3th column which give :

    39 15 00 11 08 16 07 04 22 40
    00 20 05 10 07 | 06 03 04 10 12
    03 40 08 02 23 | 50 17 01 10 15
    06 30 14 19 33 00 18 02 21 34


    What type of algorithm already exist which can do that? And How?

  2. #2
    Join Date
    Oct 2006
    Posts
    616

    Re: sort multiple reference

    Basically you are rearranging each of the matrices rows according to the sorted ordering of a given column in a given matrix.

    You just need to figure out what is the new row index of each of the rows.
    If you alter you data structure a bit, it should be easy.
    Keep on each element 2 values:
    a. The actual value of the element
    b. The index of the original row of the element.

    Before beginning the sort process - initialize the row indices(b) of all elements in the given column.
    After the sort (by element value(a) ) is complete, just linearly go over the column elements and the (b) index of the element on row i will tell you which row should be moved to row i.

    PS. If you do not wish to alter the data structure, just fill an array of size N with the indices 0 to N-1 and duplicate each sort operation you do on the matrix onto it (equivalent to adding another column of sorted numbers to the matrix).

    Kind regards,
    Zachi

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