MatLab (or any other language) to convert a matrix or a csv to put 2nd column values to the same row if 1st column value is the same?

Question

So for example I have

1st column | 2nd column

1             1
1             3
1             9
2             4
2             7

I wan

Answer 1

Use accumarray with a custom function

>> r = accumarray( A(:,1), A(:,2), [], @(x) {x'} ); %//'
 r = 
  [1x3 double]
  [1x2 double]
>> r{1}
 ans =
  1     3     9
>> r{2}
 ans =
  4     7

Update:
Converting cell r to a matrix B (accomodating further requests in comments):

>> [U ix iu] = unique( A(:,1) ); % see EitantT's comment
>> r = accumarray( iu, A(:,2), [], @(x) {x'} ); 
>> n = cellfun( @numel, r ); % fund num elements in each row - need for max
>> mx = max(n);
>> pad = 555555; % padding value
>> r = cellfun( @(x) [x pad*ones(1,mx - numel(x))], r, 'uni', 0 );
>> B = vertcat( r{:} ); % construct B from padded rows of r