Plot Gaze Fixation Data Over a Bitmap

Plot gaze fixation data overlayed on a bitmap image. This is a convenience wrapper around ggplot2::ggplot().

fixPlot(
  data,
  bgImage = NULL,
  bgAlpha = 0.33,
  xyMap = ggplot2::aes_string(x = "xpos", y = "ypos"),
  pointMap = ggplot2::aes_string(size = "dur"),
  pointAlpha = 0.5,
  mar = c(0, 0, 0, 0),
  ...,
  showPlot = TRUE
)

Arguments

data

A data.frame containing one fixation per row. Must include at least x and y coordinates. Origin is assumed to be upper left corner.

bgImage

Path to background image. Must be a PNG file. Usually this will correspond to the visual stimulus being viewed by subjects while their eye movements were recorded.

bgAlpha

Alpha level for background layer. Defaults to .33.

xyMap

Aesthetic mapping (ggplot2::aes_string()) for x and y coordinates. Passed to ggplot().

pointMap

Additional aesthetics specific to points. Passed to geom_point().

pointAlpha

Set fixation point transparency. Defaults to .5.

mar

A 4 vector for margin adjustment (x & y scale limits): top, right, bottom, left. Use positive values move margins toward center of plot (trim the display area). Use negative values to expand the display area beyond the bitmap.

...

Additional arguments passed to ggplot2::geom_point().

showPlot

Logical indicating whether to display the plot. Defaults to TRUE.

Value

A ggplot2 object.

Details

This is a convenience function for using ggplot() to lay fixation data over a background bitmap. At present, only PNG files are supported for background images. Usually, these will correspond to the visual stimulus viewed by subjects while gaze was recorded. Function returns a ggplot2 object which can be further modified by ggplot2 geoms.

Author

Dave Braze davebraze@gmail.com

Examples

data <- data.frame(x=seq(10, 1270, length.out=10),
              y=seq(10, 1014, length.out=10))
bg <- system.file("extdata/story01.png", package="FDBeye")
fixPlot(data = data,
        bgImage = bg,
        xyMap = ggplot2::aes_string(x='x', y='y'),
        pointMap =ggplot2::aes_string())


data(EToralreading)
D <- EToralreading
D$label <- as.factor(as.integer(D$label))

fixPlot(data=subset(D, subset=(subj=="s0149")&(story=="1")&(label %in% as.character(1:13))),
        bgImage=system.file("extdata/story01.png", package="FDBeye"),
        pointMap=ggplot2::aes_string(color="as.factor(as.integer(label)%%3)"), size=5,
                                     pointAlpha=.5)