Matrix Sampler
==============
.. figure:: icons/matrix-sampler.png
Samples a relation matrix.
Signals
-------
**Inputs**:
- **Data**
Data set.
**Outputs**:
- **In-sample Data**
Selected data.
- **Out-of-the-sample Data**
Remaining data.
Description
-----------
This widget samples the input data and sends both the sampled and the
remaining data to the output. It is useful for evaluating the
performance of recommendation systems.
.. figure:: images/MatrixSampler-stamped.png
1. Select the desired *sampling method*:
- **rows** (randomly samples entire matrix rows)
- **columns** (randomly samples entire matrix columns)
- **rows and columns** (samples from the entire matrix)
- **entries** (randomly samples individual matrix elements)
2. Select the proportion of the data you want at the output.
3. Press **Apply** to commit the changes.
Example
-------
**Matrix Sampler** widget samples data into two subsets: in-sample and
out-of-the-sample data. This is useful if you want to check the accuracy
of matrix reconstruction with **Completion Scoring**. Feed in-sample
data into the **Fusion Graph** to reconstruct the matrix and then
compare the results with out-of-the-sample data.
.. figure:: images/MatrixSampler-Example2.png