Annotation Table — annotation

annotation_table() modifies the data.table class to work with annotation data. The columns are of all equal length, and each row describes a single annotation (although there may be duplicate time points).

Usage

annotation_table(
  annotator = character(),
  time = character(),
  sample = integer(),
  frequency = integer(),
  type = character(),
  subtype = character(),
  channel = integer(),
  number = integer(),
  ...
)

is_annotation_table(x)

Arguments

annotator: String that is the name of a WFDB-compatible annotation type, serving as the extension for the file that is written containing that annotation. Please see read_annotation() and write_annotation() for further details.
time: A character time stamp of the annotation, written in the format of HH:MM:SS.SSS, starting at 00:00:00.000. This is converted to the appropriate time based on the header file (which records the actual start time and sampling frequency). This is often a missing variable and is given for compatibility with the WFDB applications.
sample: An integer representing the sample number of the annotation
frequency: An integer that represents the sampling frequency in Hertz
type: A character or string representing the type of the annotation
subtype: A character or string representing the subtype of the annotation
channel: An integer representing the channel number of the annotation, or a character representing the channel name
number: An additional integer value or number that classifies the annotation (allows for compatibility with multiple annotation types)
...: Additional arguments to be passed to the function
x: A data.table object that represents an annotation table

Value

A data.table that has invariant columns that are compatible with the WFDB library. The key columns include the sample index, the type of annotation (and its subtype and number qualifier), and the channel.

Details

The annotation_table() function creates a compatible table that can be used with write_annotation() and read_annotation() functions.

Annotation files

The following annotation file types are described below.

`ecgpuwave`

ecgpuwave analyzes an ECG signal from the specified record, detecting the QRS complexes and locating the beginning, peak, and end of the P, QRS, and ST-T waveforms. The output of ecgpuwave is written as a standard WFDB-format annotation file (the extension is "*.ecgpuwave", as would be expected). This file can be converted into text format using rdann. Further details are given at the ECGPUWAVE page.

The type column can be p, t, or N for the peak of the P wave, T wave, and QRS (R peak) directly. The output notation also includes waveform onset XXX and waveform offset XXX. The number column gives further information about each of these type labels.

The number column gives modifier information. If the type classifier is a T wave annotation, the number column can be 0 (normal), 1 (inverted), 2 (positive), 3 (negative), 4 (biphasic negative-positive), 5 (biphasic positive-negative). If the type is an waveform onset or offset, then number can be 0 (P wave), 1 (QRS complex), 2 (T wave).