fsqrt(VGAM)
fsqrt()所属R语言包：VGAM
Folded Square Root Link Function
倍数平方根链接功能
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Computes the folded square root transformation, including its inverse and the first two derivatives.
计算倍数的平方根变换，包括其逆和前两个衍生物。
用法----------Usage----------
fsqrt(theta, earg = list(min = 0, max = 1, mux = sqrt(2)),
inverse = FALSE, deriv = 0, short = TRUE, tag = FALSE)
参数----------Arguments----------
参数：theta
Numeric or character. See below for further details.
数字或字符。请参阅下面进一步的细节。
参数：earg
List with components min, max and mux. These are called L, U and K below.
的组件列表min，max和mux。这些被称为L，U和K下面。
参数：inverse
Logical. If TRUE the inverse function is computed.
逻辑。如果TRUE的逆函数计算。
参数：deriv
Order of the derivative. Integer with value 0, 1 or 2.
订购的衍生工具。值0，1或2的整数，带。
参数：short
Used for labelling the blurb slot of a vglmff-class object.
用于标签blurb插槽的vglmff-class对象。
参数：tag
Used for labelling the linear/additive predictor in the initialize slot of a vglmff-class object. Contains a little more information if TRUE.
用于标注线性/对添加剂的预测在initialize插槽的vglmff-class对象。如果TRUE包含了一些信息。
Details
详细信息----------Details----------
The folded square root link function can be applied to parameters that lie between L and U inclusive. Numerical values of theta out of range result in NA or NaN.
倍数的平方根链接功能可以应用到参数介于L和U包容性。数值theta出范围NA或NaN。
The arguments short and tag are used only if theta is character.
的参数short和tag只有theta是字符。
值----------Value----------
For fsqrt with deriv = 0: K * (sqrt(theta-L) - sqrt(U-theta)) or mux * (sqrt(theta-min) - sqrt(max-theta)) when inverse = FALSE, and if inverse = TRUE then some more complicated function that returns a NA unless theta is between -mux*sqrt(max-min) and mux*sqrt(max-min).
对于fsqrt与deriv = 0：K * (sqrt(theta-L) - sqrt(U-theta))或mux * (sqrt(theta-min) - sqrt(max-theta))inverse = FALSE，而如果inverse = TRUE然后一些更复杂的函数，返回一个NA 除非theta是在-mux*sqrt(max-min)和mux*sqrt(max-min)之间。
For deriv = 1, then the function returns d theta / d eta as a function of theta if inverse = FALSE, else if inverse = TRUE then it returns the reciprocal.
对于deriv = 1，则该函数返回Dtheta / Deta的函数，theta如果inverse = FALSE如果inverse = TRUE然后它返回的倒数。
注意----------Note----------
The default has, if theta is 0 or 1, the link function value is -sqrt(2) and +sqrt(2) respectively. These are finite values, therefore one cannot use this link function for general modelling of probabilities because of numerical problem, e.g., with binomialff, cumulative. See the example below.
默认情况下，如果theta是0或1，链接函数值是-sqrt(2)和+sqrt(2)分别。这些值是有限的，因此，一个不能使用这个链接功能，对于一般的概率模型，因为数值的问题，例如，用binomialff，cumulative。请看下面的例子。
（作者）----------Author(s)----------
Thomas W. Yee
参见----------See Also----------
Links.
Links。
实例----------Examples----------
p = seq(0.01, 0.99, by = 0.01)
fsqrt(p)
max(abs(fsqrt(fsqrt(p), inverse = TRUE) - p)) # Should be 0[应为0]
p = c(seq(-0.02, 0.02, by = 0.01), seq(0.97, 1.02, by = 0.01))
fsqrt(p) # Has NAs[有来港定居]
## Not run: [＃不运行：]
p = seq(0.01, 0.99, by = 0.01)
par(mfrow = c(2, 2), lwd = (mylwd <- 2))
y = seq(-4, 4, length = 100)
for(d in 0:1) {
matplot(p, cbind(logit(p, deriv = d), fsqrt(p, deriv = d)),
type = "n", col = "purple", ylab = "transformation", las = 1,
main = if (d == 0) "Some probability link functions"
else "First derivative")
lines(p, logit(p, deriv = d), col = "limegreen")
lines(p, probit(p, deriv = d), col = "purple")
lines(p, cloglog(p, deriv = d), col = "chocolate")
lines(p, fsqrt(p, deriv = d), col = "tan")
if (d == 0) {
abline(v = 0.5, h = 0, lty = "dashed")
legend(0, 4.5, c("logit", "probit", "cloglog", "fsqrt"), lwd = 2,
col = c("limegreen","purple","chocolate", "tan"))
} else
abline(v = 0.5, lty = "dashed")
}
for(d in 0) {
matplot(y, cbind(logit(y, deriv = d, inverse = TRUE),
fsqrt(y, deriv = d, inverse = TRUE)),
type = "n", col = "purple", xlab = "transformation", ylab = "p",
lwd = 2, las = 1,
main = if (d == 0) "Some inverse probability link functions"
else "First derivative")
lines(y, logit(y, deriv = d, inverse = TRUE), col = "limegreen")
lines(y, probit(y, deriv = d, inverse = TRUE), col = "purple")
lines(y, cloglog(y, deriv = d, inverse = TRUE), col = "chocolate")
lines(y, fsqrt(y, deriv = d, inverse = TRUE), col = "tan")
if (d == 0) {
abline(h = 0.5, v = 0, lty = "dashed")
legend(-4, 1, c("logit", "probit", "cloglog", "fsqrt"), lwd = 2,
col = c("limegreen","purple","chocolate", "tan"))
}
}
par(lwd = 1)
## End(Not run)[＃（不执行）]
# This is lucky to converge[这是幸运的收敛]
earg = list(min = 0, max = 1, mux = 5)
fit.h = vglm(agaaus ~ bs(altitude),
fam = binomialff(link = "fsqrt", earg = earg),
data = hunua, trace = TRUE)
## Not run: [＃不运行：]
plotvgam(fit.h, se = TRUE, lcol = "orange", scol = "orange",
main = "Orange is Hunua, Blue is Waitakere")
## End(Not run)[＃（不执行）]
head(predict(fit.h, hunua, type = "response"))
## Not run: [＃不运行：]
# The following fails.[下面的失败。]
pneumo = transform(pneumo, let = log(exposure.time))
earg = list(min = 0, max = 1, mux = 10)
fit = vglm(cbind(normal, mild, severe) ~ let,
cumulative(link = "fsqrt", earg = earg, par = TRUE, rev = TRUE),
data = pneumo, trace = TRUE, maxit = 200)
## End(Not run)[＃（不执行）]
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 2012-10-1 15:35:12
