default.expand(spatstat)
default.expand()所属R语言包：spatstat
Default Expansion Rule for Simulation of Model
默认扩展规则的仿真模型
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Defines the default expansion window or expansion rule for simulation of a fitted point process model.
定义默认的的扩展窗口或模拟的拟合点过程模型的扩展规则。
用法----------Usage----------
default.expand(object, m=2, epsilon=1e-6)
参数----------Arguments----------
参数：object
A point process model (object of class "ppm" or "rmhmodel").
A点过程模型（对象类"ppm"或"rmhmodel"）。
参数：m
A single numeric value. The window will be expanded by a distance m * reach(object) along each side.
一个单一的数值。将扩大该窗口的距离m * reach(object)每边。
参数：epsilon
Threshold argument passed to reach to determine reach(object).
阈值参数传递给reach确定reach(object)。
Details
详细信息----------Details----------
This function computes a default value for the expansion rule (the argument expand in rmhcontrol) given a fitted point process model object. This default is used by envelope, qqplot.ppm, simulate.ppm and other functions.
此函数计算的扩展规则的默认值（的说法expandrmhcontrol）给一个装有点过程模型object。使用此默认值envelope，qqplot.ppm，simulate.ppm和其他功能。
Suppose we wish to generate simulated realisations of a fitted point process model inside a window w. It is advisable to first simulate the pattern on a larger window, and then clip it to the original window w. This avoids edge effects in the simulation. It is called expansion of the simulation window.
如果我们想在一个窗口w点过程模型的拟合产生模拟的实现。可取的做法是，先模拟一个更大的窗口上的图案，然后把它夹到原来的窗口w。这避免了在模拟中的边缘效应。它被称为扩展的模拟窗口。
Accordingly, for the Metropolis-Hastings simulation algorithm rmh, the algorithm control parameters specified by rmhcontrol include an argument expand that determines the expansion of the simulation window.
因此，为大都市黑斯廷斯模拟算法rmh，算法控制参数指定的rmhcontrol包括expand，决定了扩展的模拟窗口的参数。
The function default.expand determines the default expansion rule for a fitted point process model object.
default.expand的功能确定的缺省扩展为一个装有点过程模型object规则。
If the model is Poisson, then no expansion is necessary. No expansion is performed by default, and default.expand returns a rule representing no expansion. The simulation window is the original window w = as.owin(object).
如果模型是泊松分布，没有扩展是必要的。默认情况下，无扩展和default.expand返回一个表示没有扩展的规则。仿真窗口是原来的窗口w = as.owin(object)。
If the model depends on external covariates (i.e.\ covariates other than the Cartesian covariates x and y and the marks) then no expansion is feasible, in general, because the spatial domain of the covariates is not guaranteed to be large enough. default.expand returns a rule representing no expansion. The simulation window is the original window w = as.owin(object).
如果模型依赖于外部协变量（即\协变量比笛卡尔的协变量以外x和y和marks），就没有扩展是可行的，在一般情况，因为空间域的协变量是不能保证足够大的。 default.expand返回一个表示没有扩展的规则。仿真窗口是原来的窗口w = as.owin(object)。
If the model depends on the Cartesian covariates x and y, it would be feasible to expand the simulation window, and this was the default for spatstat version 1.24-1 and earlier. However this sometimes produces artefacts (such as an empty point pattern) or memory overflow, because the fitted trend, extrapolated outside the original window of the data, may become very large. In spatstat version 1.24-2 and later, the default rule is not to expand if the model depends on x or y. Again default.expand returns a rule representing no expansion.
如果模型依赖于笛卡尔的协变量x和y，这将是可行的，扩大的仿真窗口，这是默认为spatstat1.24-1和更早的版本。然而，这有时会产生假象（如一个空的点模式）或内存溢出，因为超出了原来的窗口中的数据拟合的趋势外推，可能会变得非常大。在spatstat版本1.24-2和更高版本中，默认的规则是不扩大，如果模型依赖于x或y。 default.expand返回一个表示没有扩展的规则。
Otherwise, expansion will occur. The original window w = as.owin(object) is expanded by a distance m * rr, where rr is the interaction range of the model, computed by reach. If w is a rectangle then each edge of w is displaced outward by distance m * rr. If w is not a rectangle then w is dilated by distance m * rr using dilation.
否则，会发生膨胀。原来的窗口w = as.owin(object)的距离扩大m * rr，其中rr的相互作用的模型，计算出reach。如果w是一个矩形，然后每边w外侧的距离m * rr。 w如果是不是一个矩形，然后w扩张的距离m * rr使用dilation。
值----------Value----------
A window expansion rule (object of class "rmhexpand").
一个窗口扩展规则（类的对象"rmhexpand"）。
（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----------
rmhexpand, rmhcontrol, rmh, envelope, qqplot.ppm
rmhexpand，rmhcontrol，rmh，envelope，qqplot.ppm
实例----------Examples----------
data(cells)
fit <- ppm(cells, ~1, Strauss(0.07))
default.expand(fit)
mod <- rmhmodel(cif="strauss", par=list(beta=100, gamma=0.5, r=0.07))
default.expand(fit)
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 2012-9-30 13:21:12
