Preliminary Computations to Add Smooth Loess Curve
USAGE:
prepanel.loess(x, y, span = 2/3, degree = 1, family = "symmetric",
evaluation = 50, ...)
ARGUMENTS:
- x
-
horizontal coordinates of data points.
- y
-
vertical coordinates of data points.
- span
-
smoothing parameter.
- degree
-
overall degree of locally-fitted polynomial.
1
is locally-linear fitting and
2
is locally-quadratic fitting.
- family
-
allowable values are
"gaussian"
or
"symmetric"
.
In the first case, local-fitting methods are used.
In the second case, the default, local fitting is used together
with a robustness feature that guards against distortion
by outliers.
- evaluation
-
number of values at which the loess curve is evaluated.
VALUE:
A list with components
- dx
-
the change in
x
of each of the line segments making up the fit.
Together with
dy
, these segments are used in banking computations
to determine the aspect ratio of the Trellis plot.
- dy
-
the change in
y
of each of the line segments making up the fit.
- xlim
-
a vector of length 2 giving the minimum and maximum values for the
x
coordinates on the plot, taking into account the original data
as well as the fitted smooth curve.
- ylim
-
similar to
xlim
, but dealing with the
y
coordinates of the original
data and the fit.