我有以下数据框:
Name <- c("Apple", "Banana", "Milk")
black <- c(1, 2, 3)
white <- c(10, 5, 999)
df <- data.frame(Name, black, white)
print (df)
这将导致:
Name black white
1 Apple 1 10
2 Banana 2 5
3 Milk 3 999
我想把它 retrofit 成以下几点:
X Y Z
1 black Apple 1
2 white Apple 10
3 black Banana 2
4 white Banana 5
5 black Milk 3
6 white Milk 999