Moving Y coordinate to a new column for corresponding X values

I am new to using Matlab and have got hung up on a small problem and really appreciate any help. Using segmentation; converging the image to binary image and indexing I have created the array below, where column one is X and column two is Y.

2 155; 2 345; 3 155; 3 345; 4 154; 4 345

My aim is to move Y coordinate a new column for corresponding X values, so that I have columns X, Y1, Y2,...Yn, so the matrix becomes

2 155 345; 3 155 345; 4 154 345;

thank you in advance for taking a look.

Answer 1

[Star Strider]

Use reshape (and unique):

M = [2 155; 2 345; 3 155; 3 345; 4 154; 4 345];
[N,ia,ic] = unique(M(:,1));
Mr = [M(ia) reshape(M(:,2), 2, [])'];

[nick8631]

Thanks for the reply, however I have some errors when then this code is applied to the whole matrix

(Error using horzcat Dimensions of matrices being concatenated are not consistent. Error in lt4 (line 22) Mr = [M(ia) reshape(M(:,2), 2, [])']; )

The problem I seem to be having is some time there are more than 2 values corresponding to the x-axis, is it possible to create nth columns for the nth corresponding values. For example it fails for the data below...

3 155; 3 345; 4 154; 4 345; 5 153; 5 154; 5 345; 6 151; 6 152; 6 153; 6 345; 7 150;

Thanks nick

[Star Strider]

I couldn’t test my code on the whole matrix!

This works:

M = [3 155; 3 345; 4 154; 4 345; 5 153; 5 154; 5 345; 6 151; 6 152; 6 153; 6 345; 7 150];
[N,ia,ic] = unique(M(:,1));
for k1 = 1:size(N,1)
    Mr{k1} = [N(k1) M(ic == (k1),2)'];
end
celldisp(Mr)                            % Display Result

Answer 2

[dpb]

If it's always two pair as shown, then simply selection and rearranging works quickly...

>> xy=[2 155; 2 345; 3 155; 3 345; 4 154; 4 345];
>> [xy(1:2:end,1) reshape(xy(:,2),2,[]).']
ans =
   2   155   345
   3   155   345
   4   154   345
>>

[nick8631]

Thank you for your reply however there are often variation from 2-7 rows of corresponding values.

Thanks nick