RStudio“缺少分组变量”和“正列索引”尝试执行PERMANOVA

Question

尝试对统计数据进行统计分析作业时，我会不断收到相同的错误消息，并且不确定它们的含义/解决方法。

添加缺少的分组变量：Site 错误：[中的正列索引必须与列数匹配： * .data有3列 *位置4等于4

pots<-read.csv("http://www.nathanielwoodward.com/Pottery.csv")
install.packages("vegan")
library(vegan)
dists<-pots%>% select(Al,Fe)%>%dist()
SST<-sum(dists^2)/26
SSW<-pots%>%group_by(Site)%>%select(Al,Fe)%>%do(d=dist(.[3:4], "euclidean"))%>%ungroup()%>%
  summarize(sum(d[[1]]^2)/14 + sum(d[[2]]^2)/2+sum(d[[3]]^2)/5 +sum(d[[4]]^2)/5)%>%pull
F_obs1<-((SST-SSW)/2)/(SSW/22)
Fs1<-replicate(1000,{
  new<-pots%>%mutate(Site=sample(Site))
SSW<-new%>%group_by(Site)%>%select(Al,Fe)%>%do(d=dist(.[3:4],"euclidean"))%>%ungroup()%>%
  summarize(sum(d[[1]]^2)/14 + sum(d[[2]]^2)/2+sum(d[[3]]^2)/5 +sum(d[[4]]^2)/5)%>%pull
((SST-SSW)/2)/(SSW/26)
  })