Trying to make a 2 value sz vector, get Error using tabular/horzcat All input arguments must be tables.

Seems so simple, I'm trying to set a new table size based on values in a previous table

C = sum(app.UITable2.Data(1,:));

No matter how hard I try I can't get the sum of a single column!

So I give up and do

sz = [C(1,1) 4];

Get the weird error that all inputs must be tables!

Try making sz a known vector type

make a property

sz = [4 4] 

then try

app.sz = [C(1,1) 4];

Sorry for all the asks but I'm a very experienced C, C++ (and many other languages) programmer but this .m code is driving me crazy! Help give all kinds of useless details about setting Fonts etc but little about simple syntax for e.g. summing a column.

S = sum(A,1); does sum by columns (vs ,2 for by rows but no way to say just do column 1. Even though C is a 1x4 Can't seem to get the scaler C(1,1) out of it properly.

C(1,1) or C(1) works in the command line, just not in my app created by app designer.

Ultimately all I really want is to make a new table of the correct size with

app.TrialsTable = table('Size',sz,'VariableTypes',{'uint8','uint8','categorical','int16'});

Answer 1

[Voss]

T = table([1;2;3;4],{'ok';'let''s';'see';'here'})

T = 4x2 table
    Var1      Var2   
    ____    _________

     1      {'ok'   }
     2      {'let's'}
     3      {'see'  }
     4      {'here' }

Given the table T above, T(1,:) is another table containing the first row of T:

T(1,:) % returns a table

ans = 1x2 table
    Var1     Var2 
    ____    ______

     1      {'ok'}

and T(:,1) is another table containing the first column of T:

T(:,1) % returns a table

ans = 4x1 table
    Var1
    ____

     1  
     2  
     3  
     4  

In other words, subscripting a table using parentheses returns another table. To get the data out of a table, you can use curly brace subscripting. For example, to get the first column of table data:

T{:,1} % returns a numeric column vector, not a table

ans = 4x1

1 2 3 4

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sum(T{:,1})

ans = 10

sz = [sum(T{:,1}) 4]

sz = 1x2

10 4

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The "weird error that all inputs must be tables!" is due to trying to horizontally concatenate a table with a non-table, as in

[T(1,1) 4]

Error using tabular/horzcat (line 223)
All input arguments must be tables.

because T(1,1) is a table and 4 is not.

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html

[Alessandro Livi]

So getting data out of a table is explained but how do I put data into a table?

T{1,1} = 4; %?

or T{1,3} = 'L' % when column 3 is char

( I tried a catagorical column for 'L' and 'R' but couldn't get it to work or find help.

[Walter Roberson]

T{1,1} = 4;

and

T{1,3} = 'L';

are fine.

You should consider, though, using column names instead of column numbers:

T.Var1(1) = 4;
T.Var3(1) = 'L';

assuming the column names are Var1 and Var3

[Alessandro Livi]

Which is it () or {}? well, neither works in the App Designed code

app.TrialsTable.Var3{ii+xx} = 'R'; % right

app.TrialsTable{ii+xx, 3} = 'L'; % left

Error using {}

Conversion to cell from char is not possible.

app.TrialsTable.Var3(ii+xx) = 'L'; % left

Error using .

Conversion to cell from char is not possible.

[Walter Roberson]

app.TrialsTable.Var3(ii+xx) = {'L'};

[Voss]

Any of the following:

app.TrialsTable.Var3{ii+xx} = 'R';

app.TrialsTable.Var3(ii+xx) = {'R'};

app.TrialsTable{ii+xx, 3} = {'R'};

[Alessandro Livi]

What works is this:

LRCat = categorical({'L';'R'}); % Categorical (array?)

app.TrialsTable.Var3(ii+xx) = LRCat(1); % set left