我在R中复制了最初在Stata中完成的模拟。我用'为'循环,因为这是我知道如何使这项工作的唯一方式。运行需要很长时间,所以我想使用其中一个' apply'而不是命令,看它是否更快,但我无法弄清楚如何做到这一点。有人可以帮忙吗?这是代码:
simdiffuse <- function(a, b, c, d) {
endo <- 1/a # innovation endogenous effect
endomacro <- 1/b # category endogenous effect
appeal <- c # innovation's ex ante appeal
ninnov <- d # number of innovations in category
results <- data.frame(catdensity = rep(0:ninnov, each = 25), t = 1:25, endo = endo, endomacro = endomacro, appeal = appeal, adopt = NA)
prop <- rnorm(1000)
diff <- data.frame(prop)
diff$adopt <- 0
diff$adopt[1:5] <- 1
for (catdensity in 0:ninnov) {
diff$adopt <- 0
diff$adopt[1:5] <- 1
for (t in 1:25) {
results[results$catdensity == catdensity & results$t == t,]$adopt <- mean(diff$adopt)
for (obs in 1:nrow(diff)) {
if(appeal+(mean(diff$adopt)*endo)+(catdensity*endomacro) > rnorm(1, diff[obs,]$prop)) diff[obs,]$adopt <- 1
}
}
}
return(results)
}
results <- simdiffuse(.2, 20, -3, 60)
答案 0 :(得分:1)
您可以使用data.table
来提高功能的速度。但是,您仍然必须使用for
循环(这不是一件坏事)。
library(data.table)
simdiffuse <- function(a, b, c, d) {
endo <- 1/a # innovation endogenous effect
endomacro <- 1/b # category endogenous effect
appeal <- c # innovation's ex ante appeal
ninnov <- d # number of innovations in category
results <- data.table(catdensity = rep(0:ninnov, each = 25), t = 1:25,
endo = endo, endomacro = endomacro, appeal = appeal,
adopt = as.numeric(NA))
for (cc in 0:ninnov) {
diff <- data.table(prop = rnorm(1000), adopt = c(rep(1,5), rep(0, 995)))
for (tt in 1:25) {
results[catdensity == cc & t == tt, adopt := diff[, mean(adopt)]]
diff[, rr := rnorm(1, prop), by="prop"]
diff[appeal + mean(adopt) * endo + cc * endomacro > rr, adopt := 1]
}
}
return(results)
}
results <- simdiffuse(.2, 20, -3, 60)
我没有足够的时间等待您的代码执行,但这是我得到的adopt
与t
的图表: