Image: An Alternative Image Plotting Function

In mwrowe/microRutils: Mike Rowe's Miscellaneous R Utility Functions

Description

Image is a modified version of the image function that behaves more like Matlab imagesc.

Usage

Image(z, xaxis, yaxis, NA.color = "gray", ...)

Arguments

z	A numeric matrix or data.frame containing image data.
xaxis, yaxis	Lists of arguments to the axis. All arguments should be explicitly named. The "side" argument may be omitted. An example: xaxis=list(side=1, at=1:4, labels=LETTERS[1:4], cex.axis=0.8)
NA.color	Color for missing values. Set to NA for transparency (so the color specified by par(bg="") will show through. Note that this is accomplished by plotting a rectangle over the whole plot of the specified color, then replotting the image, so if you are adding the image to an existing plot, you may want to set this argument to NA
...	Other arguments passed to image.

Details

Image behaves like image, with the following differences:

• The z argument may be a data.frame with numeric columns; it will be automatically converted to a matrix.

• The data matrix z is transposed, so that columns run along the x-axis and rows along the y-axis.

• The direction of the y-axis is reversed, so that zero is at the top.

• If omitted, the x and y arguments are assumed from the size of z, i.e.,

  x <- 0.5 + (0:ncol(z))

  y <- 0.5 + (0:nrow(z))

  If supplied, the x and y arguments must be explicitly named.

• If a zlim argument is supplied, values outside the zlim range are replaced with the appropriate limit (floor or ceiling values to zlim).

• You may annotate the axes using the xaxis and yaxis list arguments

This behavior should be familiar to users of Matlab's imagesc function.

Author(s)

M.W.Rowe, [e-mail]

See Also

image, par.

mwrowe/microRutils documentation built on June 12, 2021, 2:41 p.m.