This is the default panel function for parallel.
panel.parallel(x, y, z, subscripts,
               groups = NULL,
               col, lwd, lty, alpha,
               common.scale = FALSE,
               lower,
               upper,
               ...,
               horizontal.axis = TRUE,
               identifier = "parallel")
dummy variables, ignored.
The data frame used for the plot. Each column will be coerced to numeric before being plotted, and an error will be issued if this fails.
The indices of the rows of z that are to be displyed in this
    panel.
An optional grouping variable.  If specified, different groups are
    distinguished by use of different graphical parameters (i.e., rows
    of z in the same group share parameters).
graphical parameters (defaults to the settings for
    superpose.line).  If groups is non-null, these
    parameters used one for each group.  Otherwise, they are recycled
    and used to distinguish between rows of the data frame z.
logical, whether a common scale should be used columns of z.
    Defaults to FALSE, in which case the horizontal range for
    each column is different (as determined by lower and
    upper).
numeric vectors replicated to be as long as the number of columns in
    z.  Determines the lower and upper bounds to be used for
    scaling the corresponding columns of z after coercing them to
    numeric.  Defaults to the minimum and maximum of each column.
    Alternatively, these could be functions (to be applied on each
    column) that return a scalar.
other arguments (ignored)
logical indicating whether the parallel axes should
    be laid out horizontally (TRUE) or vertically (FALSE).
A character string that is prepended to the names of grobs that are created by this panel function.
Deepayan Sarkar Deepayan.Sarkar@R-project.org
Produces parallel coordinate plots, which are easier to
  understand from an example than through a verbal description.  See
  example for parallel
Inselberg, Alfred (2009) Parallel Coordinates: Visual Multidimensional Geometry and Its Applications, Springer. ISBN: 978-0-387-21507-5.
Inselberg, A. (1985) “The Plane with Parallel Coordinates”, The Visual Computer.
parallel