从模拟变量中获取均值和区间

Question

我有这样的数据集：

library(data.table)
library(EnvStats)
library(bayestestR)

DT <- data.table(MEAN = c(0.5,0.7,0.9),MIN = c(0.4,0.6,0.8),MAX = c(0.6,0.8,1),REF = rnorm(3,1000,200))

我用变量 MEAN、MIN 和 MAX 的模拟值计算了一个变量。

DT[,Sim_rtri := list(REF*(1+rtri(n = 1000,min = MIN,max = MAX,mode = MEAN)))]

但是我得到了每一行相同的值，即使我需要模拟来获取每一行的值。我该怎么做？

而且，我想使用两个变量，一个的平均值为 var Sim_rtri，另一个的间隔为该 var，我试过这个：

DT[,Mean_Sim_rtri := mean(Sim_rtri)]
DT[,Int_Sim_rtri := ci(Sim_rtri, method = "ETI",ci = .95)]

但是我从中得到了错误。我还能做什么？

Answer 1

当你不分配你的第一行代码时，它会变得更清楚：

set.seed(42)
DT <- data.table(MEAN = c(0.5,0.7,0.9),MIN = c(0.4,0.6,0.8),MAX = c(0.6,0.8,1),REF = rnorm(3,1000,200))
DT[,list(REF*(1+rtri(n = 1000,min = MIN,max = MAX,mode = MEAN)))]
            V1
   1: 1946.223
   2: 1465.333
   3: 2056.410
   4: 1940.845
   5: 1504.171
  ---         
 996: 1968.724
 997: 1962.222
 998: 1511.566
 999: 2037.884
1000: 1810.734
Warning message:
In REF * (1 + rtri(n = 1000, min = MIN, max = MAX, mode = MEAN)) :
  longer object length is not a multiple of shorter object length

它正在创建一个长度为 1000 的列表而不是 3 个 list-columns（每个 1000），因为它正在回收 data.table 中的值（注意 general[= V1 的 22=] 模式是 ~1900...1500...2000。无论如何，可能有更惯用的/data.table 方法来解决问题，但使用 Map() 更符合您期望的结果？

set.seed(42) DT <- data.table(MEAN = c(0.5,0.7,0.9),MIN = c(0.4,0.6,0.8),MAX = c(0.6,0.8,1),REF = rnorm(3,1000,200)) DT[, Sim_rtri := Map(function(w, x, y, z) w*(1+rtri(n = 1000,min = x,max = y,mode = z)), REF, MIN, MAX, MEAN)] DT[, Mean_Sim_rtri := sapply(Sim_rtri, mean)] DT[, Int_Sim_rtri := lapply(Sim_rtri, ci, method = "ETI",ci = .95)] DT MEAN MIN MAX REF Sim_rtri Mean_Sim_rtri Int_Sim_rtri 1: 0.5 0.4 0.6 1274.1917 1946.223,1849.996,1933.170,1940.845,1905.784,1943.204,... 1908.901 <bayestestR_eti> 2: 0.7 0.6 0.8 887.0604 1512.938,1530.315,1480.203,1542.298,1500.740,1513.961,... 1507.717 <bayestestR_eti> 3: 0.9 0.8 1.0 1072.6257 2055.113,2085.123,1991.335,2022.209,2010.288,1984.313,... 2038.466 <bayestestR_eti>

从模拟变量中获取均值和区间

Get mean and interval from simulated var

simulation

r

data.table