Log gaze analysis
=================

[ArFrame](../../argaze.md/#argaze.ArFeatures.ArFrame) and [ArLayer](../../argaze.md/#argaze.ArFeatures.ArLayer) analysis can be logged by registering observers to their **look** method.

## Export gaze analysis to CSV file

[ArFrame](../../argaze.md/#argaze.ArFeatures.ArFrame) and [ArLayer](../../argaze.md/#argaze.ArFeatures.ArLayer) have an observers attribute to enable pipeline execution logging.

Here is an extract from the JSON ArFrame configuration file where logging is enabled for the [ArFrame](../../argaze.md/#argaze.ArFeatures.ArFrame) and for one [ArLayer](../../argaze.md/#argaze.ArFeatures.ArLayer) by pointing to dedicated Python files:

```json
{
    "name": "My FullHD screen",
    "size": [1920, 1080],
    "observers": "my_frame_logger.py",
    ...
    "layers": {
        "MyLayer": {
            "observers": "my_layer_logger.py",
            ...
        }
    }
}
```

!!! note
    [ArFrame](../../argaze.md/#argaze.ArFeatures.ArFrame) and its [ArLayers](../../argaze.md/#argaze.ArFeatures.ArLayer) automatically notify **look** method observers after each call.

Here is *my_frame_logger.py* file:

```python
from argaze import DataFeatures
from argaze.utils import UtilsFeatures

class ScanPathAnalysisLogger(DataFeatures.PipelineStepObserver, UtilsFeatures.FileWriter):

    def on_look(self, timestamp, ar_frame, exception):
        """Log scan path metrics"""

        if ar_frame.analysis_available:

            log = (
                timestamp, 
                ar_frame.scan_path_analyzers['argaze.GazeAnalysis.Basic'].path_duration, 
                ar_frame.scan_path_analyzers['argaze.GazeAnalysis.Basic'].steps_number
            )

            # Write to file
            self.write(log)

# Export logger as observer
__observers__ = {
    "Scan path analysis logger": ScanPathAnalysisLogger(path="./scan_path_metrics.csv", header=("Timestamp (ms)", "Duration (ms)", "Steps number"))
    }
```

Assuming that [ArGaze.GazeAnalysis.Basic](../../argaze.md/#argaze.GazeAnalysis.Basic) scan path analysis module is enabled for 'My FullHD screen' ArFrame, a ***scan_path_metrics.csv*** file would be created:

|Timestamp (ms)|Duration (ms)|Steps number|
|:-------------|:------------|:-----------|
|3460          |1750         |2           |
|4291          |2623         |3           |
|4769          |3107         |4           |
|6077          |4411         |5           |
|6433          |4760         |6           |
|7719          |6050         |7           |
|...           |...          |...         |

Here is *my_layer_logger.py* file:

```python
from argaze import DataFeatures
from argaze.utils import UtilsFeatures

class AOIScanPathAnalysisLogger(DataFeatures.PipelineStepObserver, UtilsFeatures.FileWriter):

    def on_look(self, timestamp, ar_layer, exception):
        """Log aoi scan path metrics."""

        if ar_layer.analysis_available:

            log = (
                timestamp,
                ar_layer.aoi_scan_path_analyzers['argaze.GazeAnalysis.NGram'].ngrams_count
            )

            # Write to file
            self.write(log)

# Export logger as observer
__observers__ = {
    "AOI Scan path analysis logger": AOIScanPathAnalysisLogger(path="./aoi_scan_path_metrics.csv", header=("Timestamp (ms)", "NGram counts"))
    }
```

Assuming that [ArGaze.GazeAnalysis.NGram](../../argaze.md/#argaze.GazeAnalysis.NGram) AOI scan path analysis module is enabled for 'MyLayer' ArLayer, a ***aoi_scan_path_metrics.csv*** file would be created:

|Timestamp (ms)|NGram counts|
|:-------------|:-----------|
|5687          |"{3: {}, 4: {}, 5: {}}"|
|6208          |"{3: {('LeftPanel', 'GeoSector', 'CircularWidget'): 1}, 4: {}, 5: {}}"|
|...           |...         |

!!! note ""

    Learn to [script the pipeline](./advanced_topics/scripting.md) to know more about [ArFrame](../../argaze.md/#argaze.ArFeatures.ArFrame) and [ArLayers](../../argaze.md/#argaze.ArFeatures.ArLayer) attributes.

### Export gaze analysis to video file

As explained in [pipeline steps visualisation chapter](visualisation.md), it is possible to get [ArFrame.image](../../argaze.md/#argaze.ArFeatures.ArFrame.image) once timestamped gaze positions have been processed by [ArFrame.look](../../argaze.md/#argaze.ArFeatures.ArFrame.look) method.

```python
from argaze import DataFeatures
from argaze.utils import UtilsFeatures

class VideoRecorder(DataFeatures.PipelineStepObserver, UtilsFeatures.VideoWriter):

    def on_look(self, timestamp, ar_frame, exception):
        """Record frame image into video file."""

        self.write(ar_frame.image())

# Export recorder as observer
__observers__ = {
    "Video recorder": VideoRecorder(path="./video.mp4", width=1920, height=1080, fps=15)
    }
```

Assuming that [ArFrame.image_parameters](../../argaze.md/#argaze.ArFeatures.ArFrame.image_parameters) are provided, ***video.mp4*** file would be created.