merge data frames (inner, outer, left, right)
数据
> df1 = data.frame(CustomerId = c(1:6), Product = c(rep("Toaster", 3), rep("Radio", 3)))
> df1
> CustomerId Product
1 1 Toaster
2 2 Toaster
3 3 Toaster
4 4 Radio
5 5 Radio
6 6 Radio
> df2 = data.frame(CustomerId = c(2, 4, 6), State = c(rep("Alabama", 2), rep("Ohio", 1)))
> df
> CustomerId State
1 2 Alabama
2 4 Alabama
3 6 Ohio
inner
> merge(x = df1, y = df2, by = "CustomerId", all = TRUE) > CustomerId Product State 1 1 Toaster <NA> 2 2 Toaster Alabama 3 3 Toaster <NA> 4 4 Radio Alabama 5 5 Radio <NA> 6 6 Radio Ohio
left
> merge(x = df1, y = df2, by = "CustomerId", all.x = TRUE) > CustomerId Product State 1 1 Toaster <NA> 2 2 Toaster Alabama 3 3 Toaster <NA> 4 4 Radio Alabama 5 5 Radio <NA> 6 6 Radio Ohio
right
> merge(x = df1, y = df2, by = "CustomerId", all.y = TRUE) > CustomerId Product State 1 2 Toaster Alabama 2 4 Radio Alabama 3 6 Radio Ohio
outer
> merge(x = df1, y = df2, by = NULL) > CustomerId.x Product CustomerId.y State 1 1 Toaster 2 Alabama 2 2 Toaster 2 Alabama 3 3 Toaster 2 Alabama 4 4 Radio 2 Alabama 5 5 Radio 2 Alabama 6 6 Radio 2 Alabama 7 1 Toaster 4 Alabama 8 2 Toaster 4 Alabama 9 3 Toaster 4 Alabama 10 4 Radio 4 Alabama 11 5 Radio 4 Alabama 12 6 Radio 4 Alabama 13 1 Toaster 6 Ohio 14 2 Toaster 6 Ohio 15 3 Toaster 6 Ohio 16 4 Radio 6 Ohio 17 5 Radio 6 Ohio 18 6 Radio 6 Ohio
