JF Benchmark Analysis for heartbeat detectors

A benchmarking analysis method that generates an overall benchmark for ECG detector algorithms, based on measurements of temporal jitter (J) and (F) score

The Glasgow University GUDB ECG recordings database (Howell and Porr, 2018) is used for testing as it has annotated R-peaks for reference. The detector algorithms are tested using recordings for all subjects, all exercises, and Einthoven II and chest strap leads (Einthoven I and Einthoven III can additionally be used if desired).

The benchmark gives a score between 0-100 where 100 is defined as the ideal detector. The ideal detector has a median absolute deviation (MAD) of zero for temporal jitter and an F-score of 100%.

Prerequisites

Install py-ecg-detectors (Howell and Porr, 2019).

via PIP:

pip install py-ecg-detectors [--user]

From source:

python setup.py install [--user]

Use the option --user if you don't have system-wise write permission.

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Install ecg_gudb_database (Howell and Porr, 2018) via the package manager pip.

pip install ecg_gudb_database

Usage

jf_analysis.py

Module which performs the JF analysis. It has no main program.

JF analysis of interval variation and F1 (FP, FN, TP):

evaluate(det_posn, anno_R, fs, nSamples, trim=True)

Arguments:

- det_posn: the timestamps of the detector in sample positions
- anno_R: the ground truth in samples
- fs: sampling rate of the ECG file
- nSamples: number of samples in the ECG file
- trim: trims 2 detections from start/end of det_posn/anno_R

Returns:

- jf[key_jitter]   : jitter in s
- jf[key_tp]       : true positive beats
- jf[key_fp]       : false positive beats
- jf[key_fn]       : false negative beats
- jf[key_f1]       : F1 score
- jf[key_jf]       : JF Score

jf_evaluate_all_detectors.py

The code evaluates all ECG detectors with all subjects, all leads, and all experiments. It outputs separate json files for every detector and stores them in the results directory.

Only needs to be run once and then can be analysed by the script below.

jf_stats_detectors.py

The overall JF Benchmark values of all detectors for Einthoven II and chest strap results are shown together on a bar graph for comparison for sitting and jogging.

jf_stats_activities.py

This analysis focusses how different noise levels affect performance from sitting to jogging.

jf_stats_detectors_sitting.py

Prints out the stats for all detectors for Einthoven and sitting. It also counts the number of QRS complexes used.

Traditional sensitivity analysis

For a sensitivity analysis on an fs/10 samples temporal window run:

python sensitivity_evaluate_all_detectors.py
python sensitivity_stats_plots.py

Note that a pure sensitivity analysis on a wide temporal window yields mostly 99-100% sensitivity.

Credit

• Bernd Porr bernd.porr@glasgow.ac.uk
• Eleanor Forsyth