关于 r：dplyr group_by 函数中的错误，找不到对象

Error in dplyr group_by function, object not found

我问这个问题是因为，作为 R 的新手，我很好奇为什么我写的一段代码可以正常工作，然后同一行代码在下次运行时会产生错误。

这是我正在使用的表的示例。

输入：

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structure(list(a5species = structure(c(4L, 1L, 6L, 3L, 14L, 3L,
8L, 8L, 8L, 8L, 8L, 8L, 3L, 4L, 4L, 8L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 8L, 8L, 8L, 8L, 8L, 8L, 4L, 8L, 8L, 8L, 3L, 8L, 8L, 8L,
12L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L,
8L, 8L, 8L, 8L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 3L, 4L, 3L, 6L,
3L, 4L, 4L, 3L, 3L, 6L, 6L, 3L, 3L, 3L, 3L, 3L, 3L, 6L, 3L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 8L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 3L, 1L, 4L, 3L, 3L, 3L, 4L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 3L,
4L, 8L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 3L, 12L, 12L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 13L, 4L, 4L, 4L, 6L, 4L, 3L,
12L, 14L, 6L, 3L, 3L, 4L, 4L, 10L, 4L, 3L, 3L, 3L, 3L, 10L, 4L,
4L, 4L, 4L, 12L, 4L, 4L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 6L, 5L, 4L, 10L, 12L, 4L, 4L, 3L, 6L, 4L, 3L,
4L), .Label = c("coustani","demeilloni","funestus","gambiae",
"garnhami","indetermine","marshallii","pharoensis","pretoriensis",
"rufipes","salbaii","squamosus","tenebrosus","ziemani"), class ="factor"),
Vila = c("Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Motaze","Motaze","Motaze",
"Motaze","Motaze","Motaze","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Chicutso","Chicutso","Chicutso",
"Chicutso","Chicutso","Panjane","Panjane","Panjane",
"Panjane","Panjane","Panjane","Panjane","Panjane","Panjane",
"Panjane","Panjane","Panjane","Panjane","Panjane","Magude",
"Magude","Magude","Magude","Magude","Magude","Magude",
"Magude","Magude","Magude","Magude","Magude","Magude",
"Magude", NA, NA,"Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Muginge", NA, NA,"Muginge",
"Muginge","Muginge","Muginge","Muginge","Muginge","Muginge",
"Muginge","Muginge","Muginge","Mapulanguene","Mapulanguene",
"Mapulanguene","Mapulanguene","Mapulanguene","Mapulanguene",
"Mapulanguene","Mapulanguene","Mapulanguene","Mapulanguene",
"Mapulanguene","Mapulanguene")), class = c("tbl_df","tbl",
"data.frame"), row.names = c(NA, -321L), .Names = c("a5species",
"Vila"))

我用这个代码来组织 Vila 的物种：

1	test %>% + group_by(Vila) %>% filter(a5species=="gambiae") %>% + summarise(n=n())

使用此代码生成了我想要的表，但下次我尝试运行代码时它停止工作并产生错误：

1 2	Error in group_by_(.data, .dots = lazyeval::lazy_dots(...), add = add) : object 'Vila' not found

我意识到这与此处发布的问题类似：
如果在使用 data.table dplyr

时在函数中定义，则找不到 R 对象

但我正在使用 dplyr_0.4.3，这个问题表明他们遇到的问题现在已经解决了，而且我的代码也确实在某个时候工作过。此外，关于这篇文章的讨论非常技术性，它超出了我的想象。

知道为什么我的代码突然停止工作了吗？

谢谢。