Title: Import Gaze Data for EyeLink Eye Tracker
Version: 1.0.3
Date: 2025-01-09
Description: Import gaze data from edf files generated by the SR Research https://www.sr-research.com/ EyeLink eye tracker. Gaze data, both recorded events and samples, is imported per trial. The package allows to extract events of interest, such as saccades, blinks, etc. as well as recorded variables and custom events (areas of interest, triggers) into separate tables. The package requires EDF API library that can be obtained at https://www.sr-research.com/support/.
License: GPL (≥ 3)
URL: https://github.com/alexander-pastukhov/eyelinkReader/, https://alexander-pastukhov.github.io/eyelinkReader/
BugReports: https://github.com/alexander-pastukhov/eyelinkReader/issues
Depends: R (≥ 4.1.0), RcppProgress, rlang
Encoding: UTF-8
NeedsCompilation: yes
VignetteBuilder: knitr
LazyData: true
LinkingTo: Rcpp, RcppProgress
Imports: dplyr, fs, purrr, Rcpp, stringr, tidyr, methods, ggplot2
RoxygenNote: 7.3.2
SystemRequirements: GNU make
Suggests: rmarkdown, knitr, testthat (≥ 3.0.0)
Config/testthat/edition: 3
Packaged: 2025-01-09 15:43:39 UTC; ba7dr4
Author: Alexander Pastukhov ORCID iD [aut, cre]
Maintainer: Alexander Pastukhov <pastukhov.alexander@gmail.com>
Repository: CRAN
Date/Publication: 2025-01-09 16:00:01 UTC

eyelinkReader: Import Gaze Data for EyeLink Eye Tracker

Description

Imports gaze data recorded by a SR Research EyeLink eye tracker from an EDF file. Includes options to import events and/or recorded samples and extract individual events such as saccades, fixations, blinks, and recorded variables.

Author(s)

Maintainer: Alexander Pastukhov pastukhov.alexander@gmail.com (ORCID)

See Also

Useful links:

Check if the library was compiled

Description

Check if the library was compiled

Usage

.onAttach(libname, pkgname)

Arguments

libname

character

pkgname

character

Value

No return value, called to check and warn if compiled EDF API interface is missing.

Compiles the library linking it to EDF API

Description

Compiles the library linking it to EDF API

Usage

.onLoad(libname, pkgname)

Arguments

libname

character

pkgname

character

Value

No return value, called to compile EDF API interface.

Adjusts message time based on embedded text offset

Description

Uses text in the message to adjust its time. E.g., for a message "-50 TARGET_ONSET" that was sent at 105600 the actual onset occurred 50 milliseconds earlier (-50). The function adjusts the event timing and removes the timing offset information from the message. I.e., the example message becomes "TARGET_ONSET" and its time become 105550.

Usage

adjust_message_time(object, prefix)

## S3 method for class 'data.frame'
adjust_message_time(object, prefix = "^[-+]?[:digit:]+[:space:]+")

## S3 method for class 'eyelinkRecording'
adjust_message_time(object, prefix = "^[-+]?[:digit:]+[:space:]+")

Arguments

object

An eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

prefix

String with a regular expression that defines the offset. Defaults to "^[-+]?[:digit:]+[:space:]+" (a string starts with a positive or negative integer offset followed by a white space and the rest of the message).

Value

Object of the same time as input, i.e., either a eyelinkRecording object with modified events slot or a data.frame with offset-adjusted events.

Examples

data(gaze)

# by passing events table
adjusted_events <- adjust_message_time(gaze$events)

# by passing the recording
gaze <- adjust_message_time(gaze)

Checks consistency flag, stops if invalid, returns code if valid.

Description

Checks consistency flag, stops if invalid, returns code if valid.

Usage

check_consistency_flag(consistency)

Arguments

consistency

consistency check control for the time stamps of the start and end events, etc. Could be 'no consistency check' (0), 'check consistency and report' (1), 'check consistency and fix' (2).

Value

integer index

Examples

check_consistency_flag('no consistency check')

Checks for validity of a logical flag, stops if not valid

Description

Checks for validity of a logical flag, stops if not valid

Usage

check_logical_flag(logical_flag)

Arguments

logical_flag

Logical scalar

Value

logical, value of the logical_flag

Examples

import_samples <- TRUE
check_logical_flag(import_samples)

Checks for validity of a string parameter, stops if not valid

Description

Checks for validity of a string parameter, stops if not valid

Usage

check_string_parameter(string_parameter)

Arguments

string_parameter

String scalar

Value

character, value of the string_parameter

Examples

start_marker <- "TRIALID"
check_string_parameter(start_marker)

Checks whether EDF API library was present and interface was successfully be compiled

Description

Checks whether EDF API library was present and interface was successfully be compiled

Usage

check_that_compiled(fail_loudly = TRUE)

Arguments

fail_loudly

logical, whether lack of compiled library means error (TRUE), just warning (FALSE), or silent (NA, for test use only).

Value

No return value. Stops the computation, if compiled interface to EDF API in missing.

Examples

check_that_compiled(fail_loudly = FALSE)

Status of compiled library

Description

Return status of compiled library

Usage

compiled_library_status()

Value

logical

Examples

compiled_library_status()

Computes cyclopean samples by averaging over binocular data

Description

Computes cyclopean samples by averaging over binocular recorded properties such as pxL/pxR, pyL/pyR, hxL/hxR, etc. Uses function specified via fun parameter to compute the average with na.rm = TRUE option. In case of a monocular recording or when the information from one eye missing, uses information from one eye only, ignoring the other column. In both binocular and monocular recording cases, simplifies column names so that pxL and/or pxR are replaced with a single column px, pyL/pyR with py, etc.

Usage

compute_cyclopean_samples(object, fun = mean)

## S3 method for class 'data.frame'
compute_cyclopean_samples(object, fun = mean)

## S3 method for class 'eyelinkRecording'
compute_cyclopean_samples(object, fun = mean)

Arguments

object

Either an eyelinkRecording object or data.frame with samples, i.e., samples slot of the eyelinkRecording object.

fun

Function used to average across eyes, defaults to mean.

Value

Object of the same time as input, i.e., either a eyelinkRecording object with modified samples slot or a data.frame with cyclopean samples.

Examples

data(gaze)

# by passing samples table
cyclopean_samples <- compute_cyclopean_samples(gaze$samples)

# storing cyclopean samples as a separate table in recording
gaze$cyclopean_samples <- compute_cyclopean_samples(gaze$samples)

# by passing the recording, cyclopean samples replace original ones
gaze <- compute_cyclopean_samples(gaze)

Convert -32767 (missing info) to NA

Description

Converts all -32767 (smallest INT16 value indicating missing info) to NA. You don't need to call this function directly, as it is automatically evoked within read_edf function.

Usage

convert_NAs(original_frame)

Arguments

original_frame

data.frame to be processed

Value

processed data.frame

Examples


  data(gaze)
  gaze$samples <- convert_NAs(gaze$samples)

Converts integer constants in trial headers to factor with explicit labels

Description

Converts integer constants in trial headers to factor with explicit labels. Please refer to EDF API manual for further details.

Usage

convert_header_codes(trial_headers)

Arguments

trial_headers

data.frame that contains trial headers.

Value

a modified trial_headers table

Converts integer constants in recordings to factor with explicit labels

Description

Converts integer constants in trial recordings information to factor with explicit labels. Please refer to EDF API manual for further details.

Usage

convert_recording_codes(trial_recordings)

Arguments

trial_recordings

data.frame that contains trial recordings.

Value

a modified trial_recordings table

Extracts rectangular areas of interest (AOI)

Description

Extracts rectangular areas of interest (AOI), as defined by "!V IAREA RECTANGLE" command. Specifically, we expect it to be in format !V IAREA RECTANGLE <index> <left> <top> <right> <bottom> <label>, where <label> is a string label and all other variables are integer. Please note that due to a non-standard nature of this function is not called during the read_edf call and you need to call it separately.

Usage

extract_AOIs(object)

## S3 method for class 'data.frame'
extract_AOIs(object)

## S3 method for class 'eyelinkRecording'
extract_AOIs(object)

Arguments

object

Either an eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

Value

Object of the same time as input, i.e., either a eyelinkRecording object with an additional AOIs slot or a data.frame with AOIs' information. See eyelinkRecording for details.

Examples

data(gaze)

# by passing the recording
gaze <- extract_AOIs(gaze)

# by passing events table
AOIs <- extract_AOIs(gaze$events)

Description

Extracts blinks from the events table of the eyelinkRecording object.. Normally, you don't need to call this function yourself, as it is called during the read_edf with default settings (e.g., import_blinks = TRUE).

Usage

extract_blinks(object)

## S3 method for class 'data.frame'
extract_blinks(object)

## S3 method for class 'eyelinkRecording'
extract_blinks(object)

Arguments

object

Either an eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

Value

Object of the same time as input, i.e., either a eyelinkRecording object with an additional blinks slot or a data.frame with blinks' information. See eyelinkRecording for details.

See Also

read_edf, eyelinkRecording

Examples

data(gaze)

# by passing the recording
gaze <- extract_blinks(gaze)

# by passing events table
blinks <- extract_blinks(gaze$events)

Extract display coordinates from an event message

Description

Extracts display coordinates from a message that adheres to a <message_prefix> <label> format. Please note that this function called during the read_edf call with silent = TRUE. If display_coords are missing from the eyelinkRecording, run this method to see the warnings.

Usage

extract_display_coords(
  object,
  message_prefix = "DISPLAY_COORDS",
  silent = FALSE
)

## S3 method for class 'data.frame'
extract_display_coords(
  object,
  message_prefix = "DISPLAY_COORDS",
  silent = FALSE
)

## S3 method for class 'eyelinkRecording'
extract_display_coords(
  object,
  message_prefix = "DISPLAY_COORDS",
  silent = FALSE
)

Arguments

object

Either an eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

message_prefix

Beginning of the message string that identifies the DISPLAY_COORDS message. Defaults to "DISPLAY_COORDS".

silent

Whether to suppress a warning when DISPLAY_COORDS message is missing. Default to FALSE.

Value

A eyelinkRecording object with an additional display_coords slot (if that was object type), Either a four element numeric vector with display coordinates, or NULL if object was an events table of eyelinkRecording object. See eyelinkRecording for details.

See Also

read_edf, eyelinkRecording

Examples

data(gaze)

# by passing the recording
gaze <- extract_display_coords(gaze)

# by passing events table
display_coords <- extract_display_coords(gaze$events)

Extract fixations

Description

Extracts fixations from the events table of the eyelinkRecording object. Normally, you don't need to call this function yourself, as it is called during the read_edf with default settings (e.g., import_fixations = TRUE).

Usage

extract_fixations(object)

## S3 method for class 'data.frame'
extract_fixations(object)

## S3 method for class 'eyelinkRecording'
extract_fixations(object)

Arguments

object

Either an eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

Value

Object of the same time as input, i.e., either a eyelinkRecording object with an additional fixations slot or a data.frame with fixations' information. See eyelinkRecording for details.

See Also

read_edf, eyelinkRecording

Examples

data(gaze)

# by passing the recording
gaze <- extract_fixations(gaze)

# by passing events table
fixations <- extract_fixations(gaze$events)

Extract saccades from recorded events

Description

Extract saccades from the events table of the eyelinkRecording object. Normally, you don't need to call this function yourself, as it is called during the read_edf with default settings (e.g., import_saccades = TRUE).

Usage

extract_saccades(object)

## S3 method for class 'data.frame'
extract_saccades(object)

## S3 method for class 'eyelinkRecording'
extract_saccades(object)

Arguments

object

Either an eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

Value

Object of the same time as input, i.e., either a eyelinkRecording object with an additional saccades slot or a data.frame with saccades' information. See eyelinkRecording for details.

See Also

read_edf, eyelinkRecording

Examples

data(gaze)

# by passing the recording
gaze <- extract_saccades(gaze)

# by passing events table
saccades <- extract_saccades(gaze$events)

Extract triggers, a custom message type

Description

Extracts trigger events, messages that adhere to a <message_prefix> <label> format. Their purpose is to identify the time instance of specific interest. Please note that due to a non-standard nature of this function is not called during the read_edf call and you need to call it separately.

Usage

extract_triggers(object, message_prefix = "TRIGGER")

## S3 method for class 'data.frame'
extract_triggers(object, message_prefix = "TRIGGER")

## S3 method for class 'eyelinkRecording'
extract_triggers(object, message_prefix = "TRIGGER")

Arguments

object

Either an eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

message_prefix

Beginning of the message string that identifies trigger messages. Defaults to "TRIGGER".

Value

Object of the same time as input, i.e., either a eyelinkRecording object with an additional triggers slot or a data.frame with triggers' information. See eyelinkRecording for details.

See Also

read_edf, eyelinkRecording

Examples

data(gaze)

# by passing the recording
gaze <- extract_triggers(gaze)

# by passing events table
triggers <- extract_triggers(gaze$events)

# with an explicit message prefix
triggers <- extract_triggers(gaze$events, "TRIGGER")

Extract variables

Description

Extracts variables from the events table of the eyelinkRecording object. Normally, you don't need to call this function yourself, as it is called during the read_edf with default settings (e.g., import_variables = TRUE).

Usage

extract_variables(object)

## S3 method for class 'data.frame'
extract_variables(object)

## S3 method for class 'eyelinkRecording'
extract_variables(object)

Arguments

object

Either an eyelinkRecording object or data.frame with events, i.e., events slot of the eyelinkRecording object.

Value

Object of the same time as input, i.e., either a eyelinkRecording object with an additional variables slot or a data.frame with variables' information. See eyelinkRecording for details.

See Also

read_edf, eyelinkRecording

Examples

data(gaze)

# by passing the recording
gaze <- extract_variables(gaze)

# by passing events table
variables <- extract_variables(gaze$events)

Class eyelinkRecording.

Description

S3 class containing information imported from an edf-file.

Details

See methods(class = "eyelinkRecording") for an overview of available methods.

Slots

preamble

A preamble of the recording, see also read_preamble.

events

Events table which is a collection of all FEVENT imported from the EDF file. See description below.

samples

Samples table which is a collection of all FSAMPLE imported from the EDF file. See description below.

headers

Headers of the individual trials, see description below.

recordings

Individual recording start/end information, see description below.

display_coords

Recorded screen coordinates (if recorded), see extract_display_coords.

saccades

Saccades extracted from events, see description below and extract_saccades.

fixations

Fixations extracted from events, see description below and extract_fixations.

blinks

Blinks extracted from events, see description below and extract_blinks.

variables

Recorded variables extracted from events, see description below and extract_variables.

triggers

Events messages that adhere to a TRIGGER <label> format. This is a non-standard message that the package author uses to mark events like onsets or offsets, similar to how it is done in M/EEG. See description below and extract_triggers.

AOIs

Areas of interest events. See description below and extract_AOIs.

Events

Events table which is a collection of all FEVENT imported from the EDF file. Column descriptions were copied directly from the EDF access C API manual. Please refer to that manual for further details. Additional non-standard fields are marked in bold.

Samples

Samples table which is a collection of all FSAMPLE imported from the EDF file. Please note that read_edf parameters determines which fields are imported. Column descriptions were copied directly from the EDF access C API manual. Please refer to that manual for further details. Suffixes L and R denote left and right eye. Non-standard additional fields are marked in bold.

Headers

Trial headers table which is a collection of all TRIAL structures imported from the EDF file. Column descriptions were copied directly from the EDF access C API manual. Please refer to that manual for further details. All fields of the RECORDINGS structure are prefixed with rec_. Non-standard additional fields are marked in bold.

Recordings

Recordings table which is a collection of all RECORDING structures imported from the EDF file. Column descriptions were copied directly from the EDF access C API manual. Please refer to that manual for further details. Non-standard additional fields are marked in bold.

Saccades and Fixations

Saccades and fixations extracted from the events, tables have the same structure. Column descriptions were copied directly from the EDF access C API manual. Please refer to that manual for further details. Non-standard additional fields are marked in bold.

Blinks

Blinks extracted from the events table. Column descriptions were copied directly from the EDF access C API manual. Please refer to that manual for further details. Non-standard additional fields are marked in bold.

Variables

User recorded variables extracted from message events with a 'TRIAL_VAR' prefix. Original format can be either 'TRIAL_VAR <name> <value>' or 'TRIAL_VAR <name>=<value>'. The <name> cannot contain spaces or '=' sign. White spaces are trimmed for both <name> and <value>.

Trigger events

Events messages that adhere to a TRIGGER <label> format. This is a non-standard message that the package author uses to mark events like onsets or offsets, similar to how it is done in M/EEG.

AOIs

Rectangular areas of interest (AOI), as defined by "!V IAREA RECTANGLE" command. Specifically, they are expected to be in format !V IAREA RECTANGLE <index> <left> <top> <right> <bottom> <label>. where <label> is a string label and all other variables are integer.

See Also

read_edf, extract_saccades, extract_fixations, extract_blinks, extract_triggers, extract_display_coords, extract_AOIs

Imported example.edf, events and samples

Description

An eyelinkRecording for example.edf via read_edf(system.file("extdata", "example.edf", package = "eyelinkReader"), import_samples = TRUE)). Contains all extracted events including triggers, areas of interested, and display coordinates. The original recording consist of ten trials with a participant fixating on a target that jumps to a new location after one second and stays on the screen for another second. Includes all relevant events.

Usage

gaze

Format

An object of class eyelinkRecording of length 12.

Details

See eyelinkRecording for details.

See Also

eyelinkRecording, read_edf

Checks validity of sample attribute vector and returns logical indexes.

Description

Checks validity of sample attribute vector and returns logical indexes.

Usage

logical_index_for_sample_attributes(import_samples, sample_attributes)

Arguments

import_samples

logical, whether importing was requested.

sample_attributes

character vector with names of attributes.

Value

logical vector

Examples

logical_index_for_sample_attributes(TRUE, c('time', 'gx', 'gy'))

Plot fixations and saccades for a set of trials

Description

This is only a basic plotting utility intended primarily for a quick visual check. Please refer to companion vignette on plotting for details about geoms and implementing your own custom plotting routine.

Usage

## S3 method for class 'eyelinkRecording'
plot(
  x,
  trial = 1,
  show_fixations = TRUE,
  fixation_size_property = "duration",
  size_legend = ifelse(fixation_size_property == "duration", "Fixation duration [ms]",
    NA),
  show_saccades = TRUE,
  saccade_color_property = "sttime_rel",
  color_legend = ifelse(saccade_color_property == "sttime_rel", "Saccade onset [ms]", NA),
  background_grobs = NULL,
  ...
)

Arguments

x

eyelinkRecording object

trial

Trials to be plotted, could be a scalar index, a vector of indexes, or NULL (all trials). Defaults to 1.

show_fixations

logical, whether to draw fixation as circles. Defaults to TRUE.

fixation_size_property

Which fixation property is used as circle aesthetics. Defaults to "duration".

size_legend

An optional legend title, defaults to "Fixation duration [ms]" if fixation_size_property is "duration" and to NA otherwise. In the latter case, the legend title is unmodified (i.e., determined by ggplot).

show_saccades

logical, whether to draw saccades as line segments. Defaults to TRUE.

saccade_color_property

Which saccade property is used as color aesthetics. Defaults to "sttime_rel" (onset time relative to the trial start).

color_legend

An optional legend title, defaults to "Saccade onset [ms]" if saccade_color_property is "sttime_rel" and to NA otherwise. In the latter case, the legend title is unmodified (i.e., determined by ggplot).

background_grobs

ggplot2 graphic objects add to the plot before plotting data.

...

Addition parameters (unused)

Value

ggplot object

Examples

data(gaze)

# fixations and saccades for the first trial
plot(gaze)

# fixations for the all trials
plot(gaze, trial = NULL, show_saccades = FALSE)

# saccades for the first two trials
plot(gaze, trial = 1:2, show_fixations = FALSE)

# color codes duration of a saccade
plot(gaze, saccade_color_property = "duration")

Print info about eyelinkRecording

Description

Print info about eyelinkRecording

Usage

## S3 method for class 'eyelinkRecording'
print(x, ...)

Arguments

x

eyelinkRecording object

...

Addition parameters (unused)

Value

No return value, called for printing to console.

Examples


  if (eyelinkReader::compiled_library_status()) {
    recording <- read_edf(system.file("extdata", "example.edf", package = "eyelinkReader"))
    print(recording)
  }

Read EDF file with gaze data recorded by SR Research EyeLink eye tracker

Description

Reads EDF file with gaze data recorded by SR Research EyeLink eye tracker and returns an eyelinkRecording object that contains events, samples, and recordings, as well as specific events such as saccades, fixations, blinks, etc.

Usage

read_edf(
  file,
  consistency = "check consistency and report",
  import_events = TRUE,
  import_recordings = TRUE,
  import_samples = FALSE,
  sample_attributes = NULL,
  start_marker = "TRIALID",
  end_marker = "TRIAL_RESULT",
  import_saccades = TRUE,
  import_blinks = TRUE,
  import_fixations = TRUE,
  import_variables = TRUE,
  verbose = TRUE,
  fail_loudly = TRUE
)

Arguments

file

full name of the EDF file

consistency

consistency check control for the time stamps of the start and end events, etc. Could be 'no consistency check', 'check consistency and report' (default), 'check consistency and fix'.

import_events

logical, whether to import events, defaults to TRUE

import_recordings

logical, whether to import information about start/end of the recording, defaults to TRUE

import_samples

logical, whether to import samples, defaults to FALSE. Please note that specifyingsample_attributes automatically sets it to TRUE.

sample_attributes

a character vector that lists sample attributes to be imported. By default, all attributes are imported (default). For the complete list of sample attributes please refer to eyelinkRecording or EDF API documentation.

start_marker

event string that marks the beginning of the trial. Defaults to "TRIALID".

end_marker

event string that marks the end of the trial. Defaults to "TRIAL_RESULT". Please note that an empty string '' means that a trial lasts from one start_marker till the next one.

import_saccades

logical, whether to extract saccade events into a separate table for convenience. Defaults to TRUE.

import_blinks

logical, whether to extract blink events into a separate table for convenience. Defaults to TRUE.

import_fixations

logical, whether to extract fixation events into a separate table for convenience. Defaults to TRUE.

import_variables

logical, whether to extract stored variables into a separate table for convenience. Defaults to TRUE.

verbose

logical, whether the number of trials and the progress are shown in the console. Defaults to TRUE.

fail_loudly

logical, whether lack of compiled library means error (TRUE, default) or just warning (FALSE).

Value

an eyelinkRecording object that contains events, samples, and recordings, as well as specific events such as saccades, fixations, blinks, etc.

Examples


  if (eyelinkReader::compiled_library_status()) {
    # Import only events and recordings information
    recording <- read_edf(system.file("extdata", "example.edf", package = "eyelinkReader"))

    # Import events and samples (only time and  screen gaze coordinates)
    recording <- read_edf(system.file("extdata", "example.edf", package = "eyelinkReader"),
                          sample_attributes = c('time', 'gx', 'gy'))

    # Import events and samples (all attributes)
    recording <- read_edf(system.file("extdata", "example.edf", package = "eyelinkReader"),
                          import_samples= TRUE)
  }

Internal function that reads EDF file

Description

Reads EDF file into a list that contains events, samples, and recordings. DO NOT call this function directly. Instead, use read_edf function that implements parameter checks and additional postprocessing.

Usage

read_edf_file(
  filename,
  consistency,
  import_events,
  import_recordings,
  import_samples,
  sample_attr_flag,
  start_marker_string,
  end_marker_string,
  verbose
)

Arguments

filename

full name of the EDF file

consistency

consistency check control (for the time stamps of the start and end events, etc). 0, no consistency check. 1, check consistency and report. 2, check consistency and fix.

import_events

load/skip loading events.

import_recordings

load/skip loading recordings.

import_samples

load/skip loading of samples.

sample_attr_flag

boolean vector that indicates which sample fields are to be stored

start_marker_string

event that marks trial start. Defaults to "TRIALID", if empty.

end_marker_string

event that marks trial end

verbose

whether to show progressbar and report number of trials

Value

contents of the EDF file. Please see read_edf for details.

Reads edf-file preamble

Description

Read the preamble of the EDF file and parses it into an reading-friendly format

Usage

read_preamble(file, fail_loudly = TRUE)

Arguments

file

name of the EDF file

fail_loudly

logical, whether lack of compiled library means error (TRUE, default) or just warning (FALSE).

Value

a character vector but with added class eyelinkPreamble to simplify printing.

Examples


 if (eyelinkReader::compiled_library_status()) {
  read_preamble(system.file("extdata", "example.edf", package = "eyelinkReader"))
}

Reads preamble of the EDF file as a single string.

Description

Reads preamble of the EDF file as a single string. Please, do not use this function directly. Instead, call read_preamble function that provides a more consistent interface.

Usage

read_preamble_str(filename)

Value

string with the preamble

Examples


if (eyelinkReader::compiled_library_status()) {
  read_preamble(system.file("extdata", "example.edf", package = "eyelinkReader"))
}