DStore
| Declaration: |
DStore: TDataTable; |
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The global variable DStore provides access to the data matrix and its related auxiliary data structures. DStore is an instance of the class TDataTable. The following table provides an overview on the properties of DStore providing access to the DataLab data structure:
In addition, there are lots of functions and procedures which let you manipulate the data table:
Filling the table cells:
Clear,
Fill,
FillRandomNormal
Handling nominal variables:
AddNominalID,
ClearNominalIDs,
CountNominalIDs,
OrdinalOfNominalID
Copying data: see table of copy operations
Counting:
CountEmptyCells,
CountImputedCells,
CountNumCells,
CountValidCells
Import/Export:
ExportAsASCFile,
ImportASCFile
Handling cell states
IfColHasCellState,
IfRowHasCellState,
InvertCellStates
Managing the size:
Resize,
InsertColumn,
InsertRow,
RemoveColumn,
RemoveRow
Basic calculations:
MeanVarOfMarkedCells,
MeanVarOfNumCells,
MinMaxOfMarkedCells,
MinMaxOfNumCells,
MinMaxOfValidCells,
PercentileOfMarkedCells,
PercentileOfNumCells,
QuartilesOfMarkedCells,
QuartilesOfNumCells,
SumOfMarkedCells,
SumOfNumCells,
CheckDichotomousColumn
Handling attributes (class numbers):
SetColAttributes,
SetRowAttributes
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| Hint: |
Please note that accessing the data by means of loops is generally much slower than by using appropriate functions of the TDataTable class (due to the interpreted p-code of the scripts). As an example, it is much faster to copy the entire data matrix using the function CopyDataTo2DArray than to copy the data elementwise. The following program shows this effect. The first part copies the entire matrix by using the function CopyDataTo2DArray, the second part does the same by utilizing two nested for loops. The speed advange of the fast version is approx. a factor of 500 when dealing with a matrix of a million cells.
program TestCopySpeed;
var
MyData1 : TDouble2DArray;
MyData2 : TDouble2DArray;
i,j : integer;
t1 : double;
begin
Resize2DArray (MyData1, DStore.NrOfColumns, DStore.NrOfRows);
t1 := CurrentTime;
DStore.CopyDataTo2DArray (MyData1,0,0,0,0,0,0);
t1 := CurrentTime-t1;
cout ('T1 [ms]: ', t1*3600*24*1000);
Resize2DArray (MyData2, DStore.NrOfColumns, DStore.NrOfRows);
t1 := CurrentTime;
for i:=1 to DStore.NrOfColumns do
for j:=1 to DStore.NrOfRows do
MyData2[i-1][j-1] := DStore.Elem[i,j];
t1 := CurrentTime-t1;
cout ('T2 [ms]: ', t1*3600*24*1000);
end.
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Programming DataLab 
