In neuroconductor-releases/eegUtils: A collection of utilities for EEG analysis

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

eeg_data objects

eeg_data objects are the base class that all objects in this framework have. When raw data is imported, the output is this class. Currently, this class is a list constituting the following entries:

• signals

  • A data frame containing the actual EEG data in wide format. Each column is data from a single electrode, each row from a single timepoint.

• srate

  • A single integer giving the sampling rate of the data in Hz

• events

  • A data.frame/tibble with 3 columns describing the events recorded in the data.
    • event_onset (in samples) relative to recording onset
    • event_time (in seconds) relative to recording onset
    • event_type (typically integer, others possible)

• chan_info

  • Typically NA on import as no channel locations are usually available in raw data.
  • A data.frame/tibble containing channel location information can be added. Currently similar to EEGLAB style, with the following columns (may change):
    • labels - channel names
    • type - Designator for channel type (e.g., EEG/EOG). Not currently used for anything.
    • theta -
    • radius
    • X
    • Y
    • Z
    • sph.theta
    • sph.phi
    • sph.radius
    • urchan
    • ref

• timings

  • A data.frame containing a description of each row in time (s) and sample numbers (samples)

• continuous

  • A logical variable indiciating if the data is continuous or epoched. To be phased out now that multiple classes exist.

• reference

  • NA on loading, in the absence of a recorded reference channel.
  • Once data is referenced, is a list consisting of two entries.
    • ref_chans - Labels for channels used to calculate the reference data. Can also be "average".
    • excluded - Labels for any channels excluded from the reference data.

eeg_epochs

eeg_epochs objects share the same overall structure with eeg_data objects, but some of the internals currently differ, as described below.

• events

  • The events table has two additional columns, epoch and time.
    • epoch gives the epoch number to which a given event belongs
    • time gives the time point at which the event occurs relative to the epoch onset
    • event_time still gives the time point at which the event occurs relative to the recording onset

• timings

  • The timings table has one additional column, epoch.
    • epoch gives the epoch number to which a given datapoint belongs
    • sample still uniquely identifies each datapoint
    • time now gives the time relative to the zero-point of the epoch, i.e. the event on which the epoch is centred.

neuroconductor-releases/eegUtils documentation built on Oct. 30, 2020, 11:06 p.m.