Help with appending onto a table in a loop

Hi All,

I have a bit of code where I am trying to create a table in a loop, appending on as each loop passes. No matter what way I try it, it only shows up with the last iteration, rather than the whole amount. Would anyone be able to help? Here is the code:

sqlTable = table;
sqlTableTemp = table;

% Doing for all non-adjusted
for i = 1:length(numModels)
    sqlTableTemp.forecastType = repmat(forecastType,length(periodEnd),1);
    sqlTableTemp.forecastName = repmat(forecastName,length(periodEnd),1);
    sqlTableTemp.modelName = repmat(modelNames{i}, length(periodEnd),1);
    sqlTableTemp.createDate = repmat(createDate,length(periodEnd),1);
    sqlTableTemp.createTime = repmat(createTime,length(periodEnd),1);
    sqlTableTemp.creator = repmat(creator,length(periodEnd),1);
    sqlTableTemp.activeForecast = zeros(length(periodEnd),1);
    sqlTableTemp.periodEnding = periodEnd;
    sqlTableTemp.val = cell2mat(app.ForecastResultsTable.UserData(:,i+1));
    sqlTable = [sqlTable;sqlTableTemp];
end

All comments and help would be appreciated.

Thanks, James

[dpb]

Looks ok so first guess is the data aren't what you think -- either maybe numModels is only 1 or whatever periodEnd is (none of these are defined in the code snippet so we've no klew where they're coming from nor what they are) is turning out to be zero (there's no data in the various forecastXXX variables, iow).

We simply can't tell; no data from which to work; not code even to see how they may have been being defined.

[Cris LaPierre]

Can you share an your variables? I can't duplicate with this 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)

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  

sqlTable = T(1,:)

sqlTable = 1×6 table
     LastName      Age    Smoker    Height    Weight    BloodPressure
    ___________    ___    ______    ______    ______    _____________

    {'Sanchez'}    38     true        71       176       124     93  

sqlTableTemp = T(1,:);

% Doing for all non-adjusted
for i = 2:height(T)
    sqlTableTemp.LastName = LastName(i);
    sqlTableTemp.Age = Age(i);
    sqlTableTemp.Smoker = Smoker(i);
    sqlTableTemp.Height = Height(i);
    sqlTableTemp.Weight = Weight(i);
    sqlTableTemp.BloodPressure = BloodPressure(i,:);
    sqlTable = [sqlTable;sqlTableTemp];
end
sqlTable

sqlTable = 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  

[dpb]

Nor could I with the cruder but more like OP's example with the beginning empty table...

>> sqlT=table;
>> tT=array2table(x);
>> sqlT=[sqlT;tT]
sqlT =
  1×5 table
    x1            x2                    x3                   x4                   x5        
    __    __________________    __________________    _________________    _________________
    0     0.0473606932701979    0.0947213865403958    0.142082079810594    0.189442773080792
>> sqlT=[sqlT;tT]
sqlT =
  2×5 table
    x1            x2                    x3                   x4                   x5        
    __    __________________    __________________    _________________    _________________
    0     0.0473606932701979    0.0947213865403958    0.142082079810594    0.189442773080792
    0     0.0473606932701979    0.0947213865403958    0.142082079810594    0.189442773080792
>> 

I'd always done similar with simply

sqlT=[];

as the placeholder into which to accumulate so just checked there wasn't something funky going on with the original empty table...

[James McBrearty]

Hi All,

The variables used are attached. Basically it is a collection of forecasts, i.e. 4 different models, and that's why I have it to loop over them all, and try and join it together. This will be used to be entered into a SQL database, and the original code done this one line at a time, so we are just changing the code to do a bulk upload instead.

It seems to do the first iteration as expected:

However, it seems that it doesn't do anymore iterations.Do you know what the issue is? I'm sure it's something simple.

[dpb]

The value of numModels over which you're looping is still undefined with the attached -- as are all the RH side variables given.

We can't even try to duplicate the example code but at least two have illustrated that the catenation would work as expected if the loop runs multiple times.

I'm with @Image Analyst, however, that it's probable the table can be built from the data directly instead, IF we could see what the starting data are instead...

[James McBrearty]

So yeah, it was a bit of an error on my part. numModels was a number that was defined earlier in the source code. I forgot about this, and was trying for find the size of the original array. It was all fixed by changing the original for loop to be

for i=1:numModels
    
end

All of the code works fine now, and is 250 times faster for sql entry than the original code that was used.

Thanks for all the help everyone

Answer 1

[Image Analyst]

Why not just do

val = cell2mat(app.ForecastResultsTable.UserData(:,i+1)); % Or whatever.
sqlTable = table(forecastType(:), forecastName(:), modelNames(:), createDate(:), ...
createTime(:), creator(:), activeForecast(:), periodEnding(:), val(:), 
'VariableNames', {'forecastType', 'forecastName', 'modelNames', 'createDate', ...
'createTime', 'creator', 'activeForecast', 'periodEnding', 'val'});