diff_nh {saccadr}

Differentiate x and y and compute change amplitude via an algorithm proposed by Nyström and Holmqvist (2010) doi:10.3758/BRM.42.1.188

Description

Differentiate x and y and compute change amplitude via an algorithm proposed by Nyström and Holmqvist (2010) doi:10.3758/BRM.42.1.188. Note that both components and the amplitude are smoothed independently via a Savitzky-Golay filter, so the components may not (probably won't) add up to the amplitude. Note that filtering is sensitive to the presence of NA.

Usage

diff_nh(x, y, trial, sample_rate, options = NULL)

Arguments

x

vector with x coordinates in degrees of visual angle

y

vector with y coordinates in degrees of visual angle

trial

vector with trial index

sample_rate

sample rate in Hz

options

List with method specific options, see Details.

Details

Method options, please refer to Nyström and Holmqvist (2010) for details on parameters and the rationale for default values.

• nh_sg_filter_order Order of Savitzky-Golay filter. Defaults to 2.

Value

data.frame with columns x, y, and amp

See Also

filter_via_savitzky_golay

Examples

diff_nh(rnorm(1000), rnorm(1000), rep(1, 1000), 250, list("nh_sg_filter_order" = 2))