====== Dataset references ======

The DatasetRef class is used not only to create a reference to a [[01_user_documentation:05_object:04_data:01_dataset|dataset]] but also to initially create a dataset.


===== Creation =====

A DatasetRef can be initialized as a class with the name of the dataset a parameter, or using the rgg library function ''dataset("DS_name")''.  If no dataset with this name exists an empty one is created.


===== Cleaning =====

To delete all data from a dataset using rgg:
<code java>

dataset("DS_name").clear();

</code>
===== Adding data =====

Adding data to the referenced dataset can be done in two different ways, either by using java functions or with overloaded operators.

With java a row is added with addRow and then the data for the cells is defined with set(<columnNr>, value): 

<code java>
dataset("DS_name").addRow().set(0,11.4).set(1,23.5);
dataset("DS_name").addRow().set(0,18.2).set(1,2.73);
</code>

Additionally with getRow(<rowNumber>) an already added row can be found to add or update cells.


The other way to do this would be to use the << operator to push data in to the dataset:

<code java>
dataset("DS_name") << 11.4 << 23.5;
dataset("DS_name") << 18.2 << 2.73;
</code>

In this way the first pushed value is added to the first column and so on.

==== Add several values to one cell ====

To add more values(up to three) to one cell the set function can be used with more values: ''set(<cloumnNr>,<xValue>,<yValue>)'' or ''set(<cloumnNr>,<xValue>,<yValue>,<zValue>)''.

Or using the operator:

<code java>
dataset("DS_name") << new doulbe[]{11.4,23.5};
</code>

===== Exporting =====

Using rgg datasets can only be exported to csv like formats using the export function:

<code java>
dataset("DS_name").export(new FileWriter(fileName));
</code>

By default this creates a file with white spaces as separators, if another separator are needed it can be defined as a second parameter ''dataset("DS_name").export(new FileWriter(fileName), ",");''.

An additional version of the two function exists with a StringBuffer as a first parameter.