Data.frame arguments



here is a confusing line of code taken from the PCA on Big Mart Sales data tutorial on this website<- data.frame(Item_Outlet_Sales= train$Item_Outlet_Sales, prin_comp$x)

prin_comp$x is one argument that I noticed is not included in R documentation. I did not know prin_comp$x can be an argument if not included in documentation. How do I interpret this argument? what is happening here in the data frame I am commanding R to create?


@rthoky4 prin_comp$x is not an argument but another column of the dataframe