lowess(stats)
lowess()所属R语言包：stats
Scatter Plot Smoothing
散点图平滑
译者：生物统计家园网 机器人LoveR
描述----------Description----------
This function performs the computations for the LOWESS smoother which uses locally-weighted polynomial regression (see the references).
这个函数执行LOWESS顺畅使用本地加权多项式回归（见参考）计算。
用法----------Usage----------
lowess(x, y = NULL, f = 2/3, iter = 3,
delta = 0.01 * diff(range(xy$x[o])))
参数----------Arguments----------
参数：x, y
vectors giving the coordinates of the points in the scatter plot. Alternatively a single plotting structure can be specified – see xy.coords.
向量给散点图中的点的坐标。或者一个单一的绘图结构，可以指定 - 见xy.coords。
参数：f
the smoother span. This gives the proportion of points in the plot which influence the smooth at each value. Larger values give more smoothness.
平滑的跨度。这给积点在每个值的影响顺利的比例。值越大，给更多的平滑。
参数：iter
the number of "robustifying" iterations which should be performed. Using smaller values of iter will make lowess run faster.
“的稳健，应执行的迭代数。使用较小的值iter会lowess跑得更快。
参数：delta
See "Details". Defaults to 1/100th of the range of x.
见“详细资料”。的x范围的百分之一默认。
Details
详情----------Details----------
lowess is defined by a complex algorithm, the Ratfor original of which (by W. S. Cleveland) can be found in the R sources as file "src/appl/lowess.doc". Normally a local linear polynomial fit is used, but under some circumstances (see the file) a local constant fit can be used. "Local" is defined by the distance to the floor(f*n)th nearest neighbour, and tricubic weighting is used for x which fall within the neighbourhood.
lowess被定义为一个复杂的算法，可以找到文件src/appl/lowess.doc的R源原件（由WS克利夫兰）Ratfor。通常用于当地的线性多项式拟合，但在某些情况下（见文件），可用于本地固定适合。 “本地”是指由距离floor(f*n)次近邻，和tricubic加权x在附近。
The initial fit is done using weighted least squares. If iter > 0, further weighted fits are done using the product of the weights from the proximity of the x values and case weights derived from the residuals at the previous iteration. Specifically, the case weight is Tukey's biweight, with cutoff 6 times the MAD of the residuals. (The current R implementation differs from the original in stopping iteration if the MAD is effectively zero since the algorithm is highly unstable in that case.)
初始适合使用加权最小二乘。如果iter > 0，进一步加权配合，使用产品的重量从x价值观和来自在上一次迭代的残差重量接近完成。具体来说，情况的重量是Tukey的biweight，截止6倍MAD残差。 （当前R的执行与停止迭代，如果MAD是有效的算法是零，因为在这种情况下，高度不稳定。从原来的）
delta is used to speed up computation: instead of computing the local polynomial fit at each data point it is not computed for points within delta of the last computed point, and linear interpolation is used to fill in the fitted values for the skipped points.
delta用于加快计算：计算，而不是在每个数据点的局部多项式拟合点内delta最后计算点，线性插值是用来计算它不填写跳过点的拟合值。
值----------Value----------
lowess returns a list containing components x and y which give the coordinates of the smooth. The smooth can be added to a plot of the original points with the function lines: see the examples.
lowess返回一个列表，其中包含组件x和y给的顺利坐标。可以顺利加入到原有的功能lines点的图：看到的例子。
参考文献----------References----------
The New S Language. Wadsworth & Brooks/Cole.
Robust locally weighted regression and smoothing scatterplots. J. Amer. Statist. Assoc. 74, 829–836.
LOWESS: A program for smoothing scatterplots by robust locally weighted regression. The American Statistician, 35, 54.
参见----------See Also----------
loess, a newer formula based version of lowess (with different defaults!).
loess，lowess（用不同的默认值！）新配方的基础版本。
举例----------Examples----------
require(graphics)
plot(cars, main = "lowess(cars)")
lines(lowess(cars), col = 2)
lines(lowess(cars, f=.2), col = 3)
legend(5, 120, c(paste("f = ", c("2/3", ".2"))), lty = 1, col = 2:3)
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。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-2-16 20:50:50
