approx (x, y, xout, method="linear", n=50, rule=1, f=0) approxfun(x, y, method="linear", rule=1, f=0)
x,y
| vectors giving the coordinates of the points to be interpolated. Alternatively a single plotting structure can be specified. |
xout
| an optional set of values specifying where interpolation is to take place. |
method
| specifies the interpolation method to be used. Choices are "linear" or "constant". |
n
|
If xout is not specified, interpolation
takes place at n equally spaced points spanning the interval
[min(x),max(x)].
|
rule
|
an integer describing how interpolation is to take
place outside the interval
[min(x),max(x)].
If rule is 1 then NAs
are returned for such points and if it is 2,
the value at the closest data extreme is used.
|
f
|
For method="constant" a number between 0 and 1 inclusive,
indicating a compromise between left- and right-continuous step
functions. If y0 and y1 are the values to the left and
right of the point then the value is y0*f+y1*(1-f) so that
f=0 is right-continuous and f=1 is left-continuous.
|
approx returns a list with components x and y,
containing n coordinates
which interpolate the given data points according to the method
(and rule) desired.
The function approxfun returns a function performing (linear or constant)
interpolation of the given data points. For a given set of x
values, this function will return the corresponding interpolated
values. This is often more useful than approx.
spline and splinefun for spline interpolation.