idw(spatstat)
idw()所属R语言包：spatstat
Inverse-distance weighted smoothing of observations at irregular points
反距离加权平滑的不规则点的观测
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Performs spatial smoothing of numeric values observed at a set of irregular locations using inverse-distance weighting.
在一组不规则的位置，使用逆距离加权的观察到的数值进行空间平滑。
用法----------Usage----------
idw(X, power=2, at="pixels", ...)
参数----------Arguments----------
参数：X
A marked point pattern (object of class "ppp").
一个显着的点模式（类的对象"ppp"）。
参数：power
Numeric. Power of distance used in the weighting.
数字。电源中的比重距离。
参数：at
String specifying whether to compute the intensity values at a grid of pixel locations (at="pixels") or only at the points of X (at="points").
字符串，用于指定是否要计算的强度值的像素位置的网格（at="pixels"）或仅在点X（at="points"）。
参数：...
Arguments passed to as.mask to control the pixel resolution of the result.
参数传递给as.mask控制的像素分辨率的结果。
Details
详细信息----------Details----------
This function performs spatial smoothing of numeric values observed at a set of irregular locations.
此功能在不规则的位置的一组观察到的数值进行空间平滑。
Smoothing is performed by inverse distance weighting. If the observed values are v[1],...,v[n] at locations x[1],...,x[n] respectively, then the smoothed value at a location u is
通过反距离权重进行平滑。如果所观察到的值是v[1],...,v[n]位置处x[1],...,x[n]分别，那么平滑值在一个位置u
where the weights are the inverse p-th powers of distance,
其中权重是逆p个权力距离，
where d(u,x[i]) is the Euclidean distance from u to x[i].
d(u,x[i])u到x[i]的欧氏距离。
The argument X must be a marked point pattern (object of class "ppp", see ppp.object). The points of the pattern are taken to be the observation locations x[i], and the marks of the pattern are taken to be the numeric values v[i] observed at these locations.
参数X必须是显着的点模式（类的对象"ppp"，看到ppp.object“）。的图案的点取为观察位置x[i]，和标记的图案被以数值v[i]观察到在这些位置。
The marks are allowed to be a data frame. Then the smoothing procedure is applied to each column of marks.
标记可以是一个数据框。然后，被施加到每一列的标记的平滑过程。
If at="pixels" (the default), the smoothed mark value is calculated at a grid of pixels, and the result is a pixel image. The arguments ... control the pixel resolution. See as.mask.
如果at="pixels"（默认值），平滑的标记值计算的像素网格，其结果是一个像素的图像。的参数...控制像素的分辨率。见as.mask。
If at="points", the smoothed mark values are calculated at the data points only, using a leave-one-out rule (the mark value at a data point is excluded when calculating the smoothed value for that point).
如果at="points"，平滑的标记值计算的数据点，使用留一出的规则（一个数据点的标记值在计算时不包括该点的平滑值）。
An alternative to inverse-distance weighting is kernel smoothing, which is performed by smooth.ppp.
反距离权重的另一种方法是核平滑，这是由smooth.ppp。
值----------Value----------
If X has a single column of marks:
如果X有一个单一的列标记：
If at="pixels" (the default), the result is a pixel image (object of class "im"). Pixel values are values of the interpolated function.
如果at="pixels"（默认值），结果是一个像素的图像（类的对象"im"“）。像素值的值的内插函数。
If at="points", the result is a numeric vector of length equal to the number of points in X. Entries are values of the interpolated function at the points of X.
如果at="points"，结果是一个数值向量的长度相等的点的数量在X。文章的插值函数在该点的X的值。
If X has a data frame of marks:
如果X有一个数据框的标记：
If at="pixels" (the default), the result is a named list of pixel images (object of class "im"). There is one image for each column of marks. This list also belongs to the class listof, for which there is a plot method.
如果at="pixels"（默认值），结果是一个名为像素的图像列表的（对象类"im"“）。有一个图像的每个列标记。这的列表也属于类listof，其中有一个图方法。
If at="points", the result is a data frame with one row for each point of X, and one column for each column of marks. Entries are values of the interpolated function at the points of X.
如果at="points"，结果是一个数据框，其中一行X，和一列的每个列的标记的每个点。文章的插值函数在该点的X的值。
（作者）----------Author(s)----------
Adrian Baddeley
<a href="mailto:Adrian.Baddeley@csiro.au">Adrian.Baddeley@csiro.au</a>
<a href="http://www.maths.uwa.edu.au/~adrian/">http://www.maths.uwa.edu.au/~adrian/</a>
and Rolf Turner
<a href="mailto:r.turner@auckland.ac.nz">r.turner@auckland.ac.nz</a>
参见----------See Also----------
density.ppp, ppp.object, im.object.
density.ppp，ppp.object，im.object。
See smooth.ppp for kernel smoothing.
见smooth.ppp核平滑的。
To perform interpolation, see also the akima package.
为了进行插值，也见akima包。
实例----------Examples----------
# data frame of marks: trees marked by diameter and height[数据框的标记：标记的直径和高度的树木]
data(finpines)
plot(idw(finpines))
idw(finpines, at="points")[1:5,]
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 2012-9-30 13:33:37
