approxfun(stats)
approxfun()所属R语言包：stats
Interpolation Functions
插值函数
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Return a list of points which linearly interpolate given data points, or a function performing the linear (or constant) interpolation.
返回列表点线性插值给定的数据点，或一个函数进行线性插值（或常数）。
用法----------Usage----------
approx (x, y = NULL, xout, method="linear", n=50,
yleft, yright, rule = 1, f = 0, ties = mean)
approxfun(x, y = NULL, method="linear",
yleft, yright, rule = 1, f = 0, ties = mean)
参数----------Arguments----------
参数：x, y
vectors giving the coordinates of the points to be interpolated. Alternatively a single plotting structure can be specified: see xy.coords.
给点坐标的向量进行插值。或者指定一个单一的绘图结构可以看到xy.coords。
参数：xout
an optional set of values specifying where interpolation is to take place.
值指定插值发生的一组可选。
参数：method
specifies the interpolation method to be used. Choices are "linear" or "constant".
指定要使用的插值方法。选择是"linear"或"constant"。
参数：n
If xout is not specified, interpolation takes place at n equally spaced points spanning the interval [min(x), max(x)].
xout如果没有被指定，插值在n跨越间隔等距点[min(x)，max(x)]。
参数：yleft
the value to be returned when input x values are less than min(x). The default is defined by the value of rule given below.
当输入x值比min(x)要返回的值。默认情况下被定义由rule下面给出的值。
参数：yright
the value to be returned when input x values are greater than max(x). The default is defined by the value of rule given below.
要返回的值时，输入x值比max(x)。默认情况下被定义由rule下面给出的值。
参数：rule
an integer (of length 1 or 2) 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. Use, e.g., rule = 2:1, if the left and right side extrapolation should differ.
描述如何插值是一个整数（长度为1或2）区间以外的地方[min(x)，max(x)]。如果rule是1然后NAS是这样的点，如果是2，在最近的数据极端值用于返回。使用，例如，rule = 2:1，如果左边和右边的推断应该有所不同。
参数：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*(1-f)+y1*f so that f=0 is right-continuous and f=1 is left-continuous.
method="constant"之间的数字0和1的包容性，表示左，右连续阶梯函数的妥协。如果y0和y1点的左侧和右侧的值，然后该值是y0*(1-f)+y1*f所以f=0是正确的连续和f=1左连续。
参数：ties
Handling of tied x values. Either a function with a single vector argument returning a single number result or the string "ordered".
绑x值的处理。无论是一个向量参数返回一个单数的结果或字符串"ordered"的功能。
Details
详情----------Details----------
The inputs can contain missing values which are deleted, so at least two complete (x, y) pairs are required (for method = "linear", one otherwise). If there are duplicated (tied) x values and ties is a function it is applied to the y values for each distinct x value. Useful functions in this context include mean, min, and max. If ties="ordered" the x values are assumed to be already ordered. The first y value will be used for interpolation to the left and the last one for interpolation to the right.
输入可以包含缺少被删除的值，所以需要至少两个完整的(x, y)对（method = "linear"，一个以其他方式）。如果有重复（并列）x值“ties是它适用于每一个不同的y值x值的功能。在这方面有用的功能包括mean，min，max。如果ties="ordered"x值被假定为已经订购。第一y值将用于插值到左边和插值权的最后一个。
值----------Value----------
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.
approx返回组件列表x和y，n坐标插值给定的数据点，根据method（rule ）所需。
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.
功能approxfun返回一个功能不良的给定数据点插值（线性或常数）。给定为x值的，这个函数将返回相应的插补值。这往往是比approx更多有用。
参考文献----------References----------
The New S Language. Wadsworth & Brooks/Cole.
参见----------See Also----------
spline and splinefun for spline interpolation.
spline和splinefun样条插值。
举例----------Examples----------
require(graphics)
x <- 1:10
y <- rnorm(10)
par(mfrow = c(2,1))
plot(x, y, main = "approx(.) and approxfun(.)")
points(approx(x, y), col = 2, pch = "*")
points(approx(x, y, method = "constant"), col = 4, pch = "*")
f <- approxfun(x, y)
curve(f(x), 0, 11, col = "green2")
points(x, y)
is.function(fc <- approxfun(x, y, method = "const")) # TRUE[真]
curve(fc(x), 0, 10, col = "darkblue", add = TRUE)
## different extrapolation on left and right side :[左边和右边的＃不同的推断：]
plot(approxfun(x, y, rule = 2:1), 0, 11,
col = "tomato", add = TRUE, lty = 3, lwd = 2)
## Show treatment of 'ties' :[＃显示的关系的待遇：]
x <- c(2,2:4,4,4,5,5,7,7,7)
y <- c(1:6, 5:4, 3:1)
approx(x,y, xout=x)$y # warning[警告]
(ay <- approx(x,y, xout=x, ties = "ordered")$y)
stopifnot(ay == c(2,2,3,6,6,6,4,4,1,1,1))
approx(x,y, xout=x, ties = min)$y
approx(x,y, xout=x, ties = max)$y
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
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发表于 2012-2-16 17:34:55
