MATLAB: I have a martix A, i want missing numbers in the 2nd column as i explained? any help?

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A =

1 3

1 5

1 6

1 8

1 10

2 4

2 8

2 9

3 1

3 3

3 5

3 7

3 9

i want output as ROWS starting with 1 = missing numbers are 2 ,4,7,9

ROWS starting with 2 = missing numbers are 1,2 ,3,5,6,7,10

ROWS starting with 1 = missing numbers are 2,4,6,8,10

Best Answer

Alternative:

T=array2table(A);
fun=@(x) setdiff(min(A(:,1)):max(A(:,2)),x);
C=rowfun(fun,T,...
    'GroupingVariable','A1',...
    'OutputFormat','cell');
Result=[repelem(unique(A(:,1)),cellfun(@length,C)) [C{:}]']

Related Solutions

MATLAB: Removing repeated numbers in a matrix

>> A = [9,9,1,1,2,2,2,2,2,0,3,3;7,7,4,4,4,5,5,6,6,6,6,6;8,8,7,7,7,8,8,8,9,9,9,5]
A =
   9   9   1   1   2   2   2   2   2   0   3   3
   7   7   4   4   4   5   5   6   6   6   6   6
   8   8   7   7   7   8   8   8   9   9   9   5
>> X = diff(A(:,[1,1:end]),1,2)~=0;
>> X(:,1) = true;
>> S = size(A);
>> [R,~] = ndgrid(1:S(1),1:S(2));
>> C = cumsum(+X,2);

Method one: accumarray:

>> B = accumarray([R(:),C(:)],A(:),[],@mode,0)
B =
   9   1   2   0   3
   7   4   5   6   0
   8   7   8   9   5

Method two: indexing:

>> B = zeros(S(1),max(C(:)));
>> B(sub2ind(S,R,C)) = A
B =
   9   1   2   0   3
   7   4   5   6   0
   8   7   8   9   5

MATLAB: Cell array summation when arrays are different sizes

Without any padding with extra zeros/NaN/etc.

Generate some indices to use accumarray to sum only the required elements:

>> in1 = {[1,1,1;2,2,2;3,3,3],[1,1,1;2,2,2;3,3,3;4,4,4;5,5,5;6,6,6],[1,1,1;2,2,2;3,3,3;4,4,4;5,5,5;6,6,6;7,7,7;8,8,8;9,9,9]}
in1 = 
    [3x3 double]    [6x3 double]    [9x3 double]
>> fun = @(m)ndgrid(1:size(m,1),1:size(m,2));
>> [i1r,i1c] = cellfun(fun,in1,'uni',0);
>> i1r = vertcat(i1r{:});
>> i1c = vertcat(i1c{:});
>> tmp = vertcat(in1{:});
>> z1a = accumarray(i1r(:),tmp(:))
z1a =
     9
    18
    27
    24
    30
    36
    21
    24
    27
>> z1b = accumarray([i1r(:),i1c(:)],tmp(:))
z1b =
     3     3     3
     6     6     6
     9     9     9
     8     8     8
    10    10    10
    12    12    12
     7     7     7
     8     8     8
     9     9     9

And similarly for the other direction:

>> in2 = {[1,2,3;1,2,3;1,2,3],[1,2,3,4,5,6;1,2,3,4,5,6;1,2,3,4,5,6],[1,2,3,4,5,6,7,8,9;1,2,3,4,5,6,7,8,9;1,2,3,4,5,6,7,8,9]}
>> [i2r,i2c] = cellfun(fun,in2,'uni',0);
>> i2r = horzcat(i2r{:});
>> i2c = horzcat(i2c{:});
>> tmp = horzcat(in2{:});
>> z2a = accumarray(i2c(:),tmp(:)).'
z2a =
     9    18    27    24    30    36    21    24    27
>> z2b = accumarray([i2r(:),i2c(:)],tmp(:))
z2b =
     3     6     9     8    10    12     7     8     9
     3     6     9     8    10    12     7     8     9
     3     6     9     8    10    12     7     8     9

Probably could be generalized for any arbitrary input arrays and requested dimension (that exercise is left up to the reader).

Best Answer

Related Solutions

MATLAB: Removing repeated numbers in a matrix

MATLAB: Cell array summation when arrays are different sizes

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