Zero Padding a Table

Hi,

Quick question om zero padding tables. I would like to add a specific number of rows to my data (quite a large table).

Below is an example:

LastName = {'Sanchez';'Johnson';'Li';'Diaz';'Brown'};
Age = [38;43;38;40;49];
Smoker = logical([1;0;1;0;1]);
Height = [71;69;64;67;64];
Weight = [176;163;131;133;119];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];

T = table(LastName,Age,Smoker,Height,Weight,BloodPressure)

I tried the following first, and got this error:

All input arguments must be tables.

T = [T; zeros(5,1)]

Then tried this, and got this error:

All tables being vertically concatenated must have the same number of variables.

 T = [T; table(zeros(5,1))]

Do I need to specify the variables? For my actual data, this would be hard, because there are a couple hundred different columns.

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/matlab/matlab_prog/add-and-delete-table-rows.html

LastName = {'Sanchez';'Johnson';'Li';'Diaz';'Brown'};
Age = [38;43;38;40;49];
Smoker = logical([1;0;1;0;1]);
Height = [71;69;64;67;64];
Weight = [176;163;131;133;119];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];
T = table(LastName,Age,Smoker,Height,Weight,BloodPressure)

T = 5×6 table
     LastName      Age    Smoker    Height    Weight    BloodPressure
    ___________    ___    ______    ______    ______    _____________

    {'Sanchez'}    38     true        71       176       124     93  
    {'Johnson'}    43     false       69       163       109     77  
    {'Li'     }    38     true        64       131       125     83  
    {'Diaz'   }    40     false       67       133       117     75  
    {'Brown'  }    49     true        64       119       122     80  

emp = {'', nan, false, nan, nan, [nan nan]};
T1 = [T;repmat(emp,5,1)]

T1 = 10×6 table
     LastName      Age    Smoker    Height    Weight    BloodPressure
    ___________    ___    ______    ______    ______    _____________

    {'Sanchez'}     38    true        71       176       124     93  
    {'Johnson'}     43    false       69       163       109     77  
    {'Li'     }     38    true        64       131       125     83  
    {'Diaz'   }     40    false       67       133       117     75  
    {'Brown'  }     49    true        64       119       122     80  
    {0×0 char }    NaN    false      NaN       NaN       NaN    NaN  
    {0×0 char }    NaN    false      NaN       NaN       NaN    NaN  
    {0×0 char }    NaN    false      NaN       NaN       NaN    NaN  
    {0×0 char }    NaN    false      NaN       NaN       NaN    NaN  
    {0×0 char }    NaN    false      NaN       NaN       NaN    NaN  

Answer 2

[Adam Danz]

Starting in MATLAB R2023b, you can use paddata to pad tables.

LastName = {'Sanchez';'Johnson';'Li';'Diaz';'Brown'};
Age = [38;43;38;40;49];
Smoker = logical([1;0;1;0;1]);
Height = [71;69;64;67;64];
Weight = [176;163;131;133;119];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];
T = table(LastName,Age,Smoker,Height,Weight,BloodPressure)

T = 5×6 table
     LastName      Age    Smoker    Height    Weight    BloodPressure
    ___________    ___    ______    ______    ______    _____________

    {'Sanchez'}    38     true        71       176       124     93  
    {'Johnson'}    43     false       69       163       109     77  
    {'Li'     }    38     true        64       131       125     83  
    {'Diaz'   }    40     false       67       133       117     75  
    {'Brown'  }    49     true        64       119       122     80  

To pad a fixed number of rows,

nTotalRows = height(T) + 5;   % pad 5 rows

paddata(T,nTotalRows)

ans = 10×6 table
      LastName      Age    Smoker    Height    Weight    BloodPressure
    ____________    ___    ______    ______    ______    _____________

    {'Sanchez' }    38     true        71       176       124     93  
    {'Johnson' }    43     false       69       163       109     77  
    {'Li'      }    38     true        64       131       125     83  
    {'Diaz'    }    40     false       67       133       117     75  
    {'Brown'   }    49     true        64       119       122     80  
    {0×0 double}     0     false        0         0         0      0  
    {0×0 double}     0     false        0         0         0      0  
    {0×0 double}     0     false        0         0         0      0  
    {0×0 double}     0     false        0         0         0      0  
    {0×0 double}     0     false        0         0         0      0  

There's an option to specify the fill value which you could set to missing but this only works when all table variables have a missing indicator. This demo table contains a cell array which does not support missing.

paddata(T,nTotalRows,'FillValue',missing)