sampfle(sampfling)
sampfle()所属R语言包：sampfling
Random Sampling: the Sampford Algorithm
随机抽样：Sampford算法
译者：生物统计家园网 机器人LoveR
描述----------Description----------
sampfle implements the Sampford algorithm to obtain a sample without replacement and with unequal probabilities. The probability
sampfle实现Sampford算法获得的样本，无需更换和不等概率。的概率
用法----------Usage----------
sampfle(x, size, prob = NULL)
参数----------Arguments----------
参数：x
Either a (numeric, complex, character or logical) vector of more than one element from which to choose, or a positive integer.
无论是（数字的，复杂的，字符或逻辑）的矢量中的一个以上的元素，可以从中选择，或一个正整数。
参数：size
A positive integer giving the number of items to choose.
一个正整数，给出的数字中选择的项目。
参数：prob
A vector of weights for obtaining the elements of the vector being sampled.
一种向量，用于获得被采样的矢量的元素的权重。
Details
详细信息----------Details----------
If x has length 1, sampling takes place from 1:x.
如果x的长度为1，采样发生1:x。
The prob argument gives a vector of weights for obtaining the elements of the vector being sampled. They need not sum to one, but they should be nonnegative and, after normalizing, less than 1/size. The number of nonzero weights must be at least size.
prob参数给出了一个用于获得被采样的矢量的元素的权重向量。他们需要一个总结，但他们应该是非负的，归一化后，不到1/size。非零的权重的数目必须至少size。
The Sampford algorithm draws the first unit i with probability proportional to prob, and subsequent units with probabilities proportional to prob/(1-size*prob[i]) with replacement. As soon as a unit is repeated, the entire sample is rejected and the process is restarted. Thus a sample without replacement is obtained.
Sampford算法绘制第一单元iprob，prob/(1-size*prob[i])与更换成比例的概率和随后的单位比例的概率。只要一个单元重复，将整个样品被拒绝，并且在重新启动的过程。因此无需更换的样品得到的。
The algorithm produces a sample s, subset of x of size n, with probability proportional to
该算法产生的样本s，x大小n“的概率是成正比的子集
值----------Value----------
A vector, which contains the sampled units from x, or indices if x is an integer.
一个向量，其中包含x，或指数的采样单位，如果x是一个整数。
（作者）----------Author(s)----------
Carlos Enrique Carleos Artime <a href="mailto:carleos@vodafone.es.">carleos@vodafone.es.</a>
参考文献----------References----------
Cochran, W.G. (1977) Sampling techniques, John Wiley and Sons.
Sampford, M.R. (1967) On sampling without replacement with unequal probabilities of selection, Biometrika 54:499-513.
参见----------See Also----------
samprop
samprop
实例----------Examples----------
library(sampfling)
sampfle(10, 3, 1:10)
sampfle(c("a","b","c"), 2, c(0.3,0.3,0.4))
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 2012-9-29 21:31:39
