How to create new rows in a table based on nested cell arrays of different sizes

So I have a table that contains nested cell arrays in only one column. What I'd like to accomplish is create a new table that has the contents of each cell made into new rows below the original row.

Ive attached a sample of what the data looks like(file), as well as what id like to accomplish(file2). I'd like to accomplish this for every embedded cell.

Answer 1

[Stephen23]

This is MATLAB, so do not use on concatenation within loops to achieve this task. Better:

S1 = load('file.mat');
S2 = load('file2.mat');
T1 = S1.non_compliance_B % provided input

T1 = 9×9 table
        ID        PayloadElectronicsUnitSubsystemSpecification    LastModifiedOn    ProposedVerifDescription    ProposedText    ObjectType    ChildTraceabilityCount    ChildTraceability        RvCCompliance    
    __________    ____________________________________________    ______________    ________________________    ____________    __________    ______________________    _________________    _____________________

    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                 {16×1 cell}       "Marginal Compliance"
    "PEU-389"                      {0×0 cell}                      27-Feb-2023             {0×0 char}            {0×0 char}      {'Req'}                 9                 { 9×1 cell}       "Non-Compliance"     
    "PEU-840"                      {0×0 cell}                      27-Feb-2023             {0×0 char}            {0×0 char}      {'Req'}                33                 {33×1 cell}       "Marginal Compliance"
    "PEU-280"                      {0×0 cell}                      28-Feb-2023             {0×0 char}            {0×0 char}      {'Req'}                 8                 { 8×1 cell}       "Non-Compliance"     
    "PEU-2595"                     {0×0 cell}                      16-Apr-2023             {0×0 char}            {0×0 char}      {'Req'}                 5                 { 5×1 cell}       "Non-Compliance"     
    "PEU-2591"                     {0×0 cell}                      16-Apr-2023             {0×0 char}            {0×0 char}      {'Req'}                 5                 { 5×1 cell}       <missing>            
    "PEU-730"                      {0×0 cell}                      27-Feb-2023             {0×0 char}            {0×0 char}      {'Req'}                 6                 { 6×1 cell}       "Non-Compliance"     
    "PEU-2586"                     {0×0 cell}                      16-Apr-2023             {0×0 char}            {0×0 char}      {'Req'}                 5                 { 5×1 cell}       "Non-Compliance"     
    "PEU-956"                      {0×0 cell}                      27-Feb-2023             {0×0 char}            {0×0 char}      {'Req'}                 6                 { 6×1 cell}       "Non-Compliance"     

T2 = S2.bal % desired output

T2 = 24×9 table
        ID        PayloadElectronicsUnitSubsystemSpecification    LastModifiedOn    ProposedVerifDescription    ProposedText    ObjectType    ChildTraceabilityCount    ChildTraceability        RvCCompliance    
    __________    ____________________________________________    ______________    ________________________    ____________    __________    ______________________    _________________    _____________________

    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'PRS-738'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'PRS-762'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'PRS-910'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RF1-553'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RF1-560'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO-993' }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO-1000'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO-1002'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO2-147'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO2-156'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO2-294'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2566'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2582'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2583'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2584'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2585'     }      "Marginal Compliance"

L = cellfun(@numel,T1.ChildTraceability);
T3 = repelem(T1,L,1);
T3.ChildTraceability = vertcat(T1.ChildTraceability{:})

T3 = 93×9 table
        ID        PayloadElectronicsUnitSubsystemSpecification    LastModifiedOn    ProposedVerifDescription    ProposedText    ObjectType    ChildTraceabilityCount    ChildTraceability        RvCCompliance    
    __________    ____________________________________________    ______________    ________________________    ____________    __________    ______________________    _________________    _____________________

    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'PRS-738'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'PRS-762'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'PRS-910'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RF1-553'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RF1-560'  }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO-993' }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO-1000'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO-1002'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO2-147'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO2-156'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'RFIO2-294'}      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2566'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2582'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2583'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2584'     }      "Marginal Compliance"
    "PEU-2069"                     {0×0 cell}                      05-May-2023             {0×0 char}            {0×0 char}      {'Req'}                16                {'2585'     }      "Marginal Compliance"

[Santiago Chazaro]

Thank you so much!

[Peter Perkins]

Stephen23 is 100% correct, but in case anyone needs an explanation of this somewhat advanced trick:

1) each cell of ChildTraceability contains a column with multiple rows. Nothing wrong with that, it's how you "multiple rows in one row of a table".

2) To move those "inner" rows out to the table itself, we need to make copies of each of T1's rows so there is one row for each of the "inner rows". That's what the repelem does. But it also makes copies of each of the cells in ChildTraceability, and we want to "explode" them instead.

3) So turn ChildTraceability into a cell column with one char row in each cell by first applying {:} to get all the contents of all the cells, and then vertcat to put those into one column of cells. This takes some thought, because ChildTraceability is a cell array each of whose cells contains a cell array (or char row vectors). Strings (i.e. double quotes) would make this easier to think about!

4) I might go one step further and turn ChildTraceability into a categorical variable, but not if its values are all unique

Answer 2

[Akira Agata]

How about the following?

load("file.mat");

bal = table();

for kk = 1:height(non_compliance_B)
  t = non_compliance_B(kk, :);
  t = t(ones(t.ChildTraceabilityCount, 1), :);
  t.ChildTraceability = t.ChildTraceability{1};
  bal = [bal; t]; %#ok
end

[Santiago Chazaro]

Nice solution, however this comment is throwing me off: This is MATLAB, so do not use on concatenation within loops to achieve this task. @Stephen23 could you explain what you mean ?

[Stephen23]

" however this comment is throwing me off"

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

https://www.mathworks.com/help/matlab/matlab_prog/techniques-for-improving-performance.html

[Santiago Chazaro]

Thanks!