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.

## Enable ArFrame and ArLayer analysis logging

[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, frame):
        """Log scan path metrics"""

        if frame.analysis_available:

            log = (
                timestamp, 
                frame.scan_path_analyzers['argaze.GazeAnalysis.Basic'].path_duration, 
                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, layer):
        """Log aoi scan path metrics"""

        if layer.analysis_available:

            log = (
                timestamp,
                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: {}}"|
|...           |...         |