我已经创建了混合逻辑模型的模拟数据。涉及N位钓鱼者进行两次旅行,每次旅行可以前往两个不同的地点之一。以下是创建模拟数据的代码:
library(data.table)
library(mlogit)
### Angler choice probabilities for site a
N <- 1e4
beta <- rnorm(N, mean = 0.5)
val <- runif(N)
p <- exp(1 + beta*val)/(1+ exp(1 + beta*val))
### Choice for trip 1
Y11 <- rbinom(N, 1, p)
Y10 <- 1 - Y11
### Choice for trip 2
Y21 <- rbinom(N, 1, p)
Y20 <- 1 - Y21
### Data set
id <- as.character(1:N)
sim <- data.table(angler = rep(id, 4),
trip = paste(id, rep(1:2, each = 2*N), sep = "_"),
site = c(rep(letters[1:2], each = N),
rep(letters[1:2], each = N)),
is_choice = as.logical(c(Y11, Y10, Y21, Y20)),
term = c(val, rep(0, N), val, rep(0, N)))
sim[, term2 := ifelse(site == "a", 1, 0)]
当我运行mlogit时,出现以下错误:
> mlogit(is_choice ~ 1, sim, shape = "long", alt.var = "site", chid.var = "trip", id.var = "angler")
Error in str2lang(x) : <text>:2:0: unexpected end of input
1: . ~ . |
^
我可以运行vignette中的示例,因此似乎没有安装问题。
那么我错在哪里了?谢谢!