MATLAB: Matrix “addition” qeustion

matrix math

How do I create a matrix A which is equal to a matrix X with column vectors added onto it which are the element wise square and cube of some of the columns of X? I have a matrix that is 32413×46 and I want to take columns 12-18, square them and add them as columns 47-53 to the previous matrix and then take those same columns 12-18, cube them and add them on as columns 54-60.

Best Answer

Right, you don't have a matrix but a table. Using correct term avoids wasting everyone time. matrices and tables are two completely different things.

All columns of a table must be named. I question the wisdom of adding so many columns to a table, particularly as the value are trivial to calculate whenever you need them, but if it needs to be done, the simplest thing would be to prepend (or append) the names of the existing columns with 'squared' and 'cubed' respectively. This is easily done:

yourtable = array2table(randi([0 100], 20, 46));    %demo table
newtable = [yourtable, ...
            array2table(yourtable{:, 12:18} .^2, 'VariableNames', compose('squared_%s', string(yourtable.Properties.VariableNames(12:18)))), ...
            array2table(yourtable{:, 12:18} .^3, 'VariableNames', compose('cubed_%s', string(yourtable.Properties.VariableNames(12:18))))]

Related Solutions

MATLAB: How to add variables to a table that are products of other variables

cur_varnames = YourTable.Properties.VariableNames;
for K = [10, 12:18]
  thisvarname = cur_varnames{K};
  thisval = YourTable.(thisvarname);
  sq_varname = [thisvarname '_squared'];
  cu_varname = [thisvarname '_cubed'];
  YourTable.(sq_varname) = thisval .^ 2;
  YourTable.(cu_varname) = thisval .^ 3;
end

MATLAB: Create matrix with periodic increments

The function bsxfun is really handy for these kind of tasks:

>> X = [1;2;3;4;5;6];
>> Y = bsxfun(@plus,X,0:10:40);
>> Z = bsxfun(@plus,Y(:),0:20);
>> Z
Z =
    1    2    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21
    2    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22
    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23
    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24
    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25
    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26
   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31
   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32
   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33
   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34
   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35
   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36
   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41
   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42
   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43
   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44
   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45
   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46
   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51
   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52
   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53
   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54
   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55
   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56
   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61
   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61   62
   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61   62   63
   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61   62   63   64
   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61   62   63   64   65
   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61   62   63   64   65   66

Best Answer

Related Solutions

MATLAB: How to add variables to a table that are products of other variables

MATLAB: Create matrix with periodic increments

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