MATLAB: Adding values to table at each step

append to tableismembermatching

Hi,

I have a table 1x 5 eg values with code names such as:

C='ABO1'    'ABO2'    'ADE3'    'ADE4'    'AGUG' 'ACE4'

And I have many other tables, each one generated at time step like:

table 1 step 1:
'ABO1'  7521.3
'ABO2'  12360
'ACE4'  540
'AGUG'  558.5

and table 2 step 2 e.g.:

'ACE4'  0.5
'AGUG'  2

I would like to fill the first table at each time step with corresponding values if there are, if not put nan. So that resulting table would look like:

      'ABO1' 'ABO2' 'ADE3' 'ADE4' 'AGUG' 'ACE4'
  1   7521.3 12360  nan     nan    558.2  nan
  2    nan    nan   nan     nan    2      nan

thanks a lot for any hints!

Best Answer

If I understood correctly you're generating tables in a loop and want to fill another table one row at a time at each step of the loop, in which case:

codes = {'ABO1'    'ABO2'    'ADE3'    'ADE4'    'AGUG' 'ACE4'};
maintable = array2table(zeros(0, numel(codes)+1), 'VariableNames', ['step', codes]);  %create empty destination table
%your loop replace by actual code
numsteps = 10;
looptables = cell(numsteps, 1);
for step = 1:numsteps   %your loop, replace by actual code
  %random generation of loop table, replace by actual code
  randrows = randi(numel(codes));
  looptable = table(codes(randperm(numel(codes), randrows))', rand(randrows, 1)*20000, 'VariableNames', {'codes', 'values'});
  looptables{step} = looptable;
    %filling of the main table
    filler = nan(1, numel(codes));
    [~, destcol] = ismember(looptable.codes, codes);
    filler(destcol) = looptable.values;
    maintable{step, :} = [step, filler];
  end
  maintable

Note that, assuming you've kept all the looptables around, the same can be achieved in one go at the end of the loop with:

maintable2 = vertcat(looptables{:});
maintable2.step = repelem((1:numel(looptables))', cellfun(@height, looptables));
maintable2 = unstack(maintable2, 'values', 'codes')

Related Solutions

MATLAB: How to re-code numeric variables in a table to strings

JLC, you say "string", but it's very likely that you would be bettter off with categorical variables. Given you're original sample data ...

>> Var1 = [1; 2; 1; 2; 2; 1; 1];
>> Var2 = [2; 2; 1; 1; 1; 2; 1];
>> Var3 = [32.1; 34.6; 56.7; 65.3; 78.6; 23.4; 43.1];
>> t = table(Var1,Var2,Var3)
t =
  7×3 table
    Var1    Var2    Var3
    ____    ____    ____
     1       2      32.1
     2       2      34.6
     1       1      56.7
     2       1      65.3
     2       1      78.6
     1       2      23.4
     1       1      43.1
... here's what you probably want to do:
>> t.Var1 = categorical(t.Var1,1:2,{'Male' 'Female'});
>> t.Var2 = categorical(t.Var2,1:2,{'Old' 'Young'});
>> t
t =
  7×3 table
     Var1     Var2     Var3
    ______    _____    ____
    Male      Young    32.1
    Female    Young    34.6
    Male      Old      56.7
    Female    Old      65.3
    Female    Old      78.6
    Male      Young    23.4
    Male      Old      43.1

A few other things:

Don't name your table "Table". It will come back to bite you eventually.
No reason to concatenate [Var1,Var2,Var3] and then call array2table, which just pulls them apart. Call table directly.
Your "desired" result seems to have Var3 as a cell array, each cell containing a scalar double, You definitely don't want that.
It's possible to convert the entire table to a cell array and work on it and convert it back, as shown by ImageAnalyst. But you can work on the table directly as I showed above. The "Conversion to double from cell is not possible." errors you saw are because, as IA says, you were assigning text to only some elements of a double variable in the table. You need to assign to t.Var1 without subscripting. My code above shows that as part of converting to categorical.
If you really do want strings, do it like this:

genders = {'Male'; 'Female'}; t.Var1 = genders(t.Var1);
ages = {'Male'; 'Female'}; t.Var2 = ages(t.Var2);

MATLAB: Finding string in between

yourNumber is overwritten in the loop and only the last value is saved. The first step to fix your code is

yourNumber = cell( length(fs_indices), 1 );
for i = 1 : length(fs_indices)
    yourNumber{i} = somestring{i}(underscore_indices(i)+2:your_number(i)-1);
end

There are other ways, e.g. with regular expressions

>> str = '18WABO1-12345-0X';
>> regexp( str, '(?<=18W)[^\-]+(?=\-)', 'match' )
ans = 
    'ABO1'

and

    cac = { 
            '18WABO1-12345-0X'
            '18WABO2-12345-0N'
            '18WACE3-12345-00'
            '18WACE4-12345-0R'
            '18WAGUG-12345-0G'
            '18WDUER-12345-0N' };
    %    
    out = regexp( cac, '(?<=18W).+?(?=\-)', 'match' ); 
    out = cat( 1, out{:} );

and

>> out
out = 
    'ABO1'
    'ABO2'
    'ACE3'
    'ACE4'
    'AGUG'
    'DUER'

and with indexing

>> str = char( cac );
>> str = str( :, 4:7 )
str =
ABO1
ABO2
ACE3
ACE4
AGUG
DUER
>>

Best Answer

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MATLAB: How to re-code numeric variables in a table to strings

MATLAB: Finding string in between

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