Transpose single column onto a Geometry

Hi, I have (26 x 1) W = 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46, and want to use X(26 x 2) which is the address matrix for G...

X =

     2     2
     3     2
     4     2
     2     3
     3     3
     4     3
     2     4
     3     4
     4     4
     2     5
     3     5
     4     5
     2     6
     3     6
     4     6
     2     7
     3     7
     4     7
     2     8
     3     8
     4     8
     2     9
     3     9
     4     9
     2    10
     3    10,

to transpose W onto: G =

    -1    -1    -1    -1    -1    -1    -1    -1    -1    -1
    -1     0     0     0     0     0     0     0     0     0
    -1     0     0     0     0     0     0     0     0     0
    -1     0     0     0     0     0     0     0     0     5

Answer 1

[Star Strider]

This is a variation on your earlier Question How to index a matrix, and the solution is similar:

%Matrix size
columns=10;
rows=4;
%Blank matrix
X = zeros(4,10);

%Fill matrix (1st row & first column)
newrow =-ones(1,columns);    % the row to replace row 1 with
newcolumn=-ones(rows,1);     % the column to replace column 1 with

X(1,:)= newrow ;         % replace row 1 in a with new
X(:,1) = newcolumn(:);          % replace column 1 in a with new

zi = find(X == 0);
X(zi) = [W; 5]'

X =

      -1    -1    -1    -1    -1    -1    -1    -1    -1    -1
      -1    21    24    27    30    33    36    39    42    45
      -1    22    25    28    31    34    37    40    43    46
      -1    23    26    29    32    35    38    41    44     5

[Aswas]

Starstrider, can I please have the transposition L-R, rather than top to bottom.

[Star Strider]

Sure!

Replace the ‘X(zi)’ assignment with:

X(zi) = reshape([W' 5], [], 3)'

to produce:

X =
    -1    -1    -1    -1    -1    -1    -1    -1    -1    -1
    -1    21    22    23    24    25    26    27    28    29
    -1    30    31    32    33    34    35    36    37    38
    -1    39    40    41    42    43    44    45    46     5

[Aswas]

Hi Starstrider, when I reduce to 6 columns and 2 rows, I get error: Error using reshape Product of known dimensions, 3, not divisible into total number of elements, 5.

Error in Untitled (line 54) X(zi) = reshape([W' 5], [], 3)'

[Star Strider]

You have to change the size of the matrix you want reshape to produce. See if this works:

X(zi) = reshape([W' 5], [], 2)'

Here, I tell it to produce a matrix of 2 columns instead of 3 as before, then (as before) use the transpose operator (') to produce the 2-row matrix you want.

Note that the ‘5’ in the vector is the value you want at the end.

See the documentation for the reshape function for details on how to tell it to do what you want. It is versatile, but it has some necessary constraints.

[Aswas]

Thank you very much Starstrider, sorted.

[Star Strider]

As always, my pleasure.