将 R Dataframe 从长格式转换为宽格式并连接字符串值

Question

我有这样一个数据框：

df <- data.frame (Subject = c(1,1,1,2,2,3,3), Product = c("A","B","C","B","C","A","D")

我想像这样替换它（变成 "wide" 格式）：

df_replace <- data.frame(Subject = c(1,2,3), Product = c("A;B;C","B;C","A;D"))

新产品值应该是给定主题的原始产品值的串联字符串。

我正在试验 dcast ...但我还没有找到继续前进的方法。（但我假设......这很简单）。

Answer 1

您可以使用 aggregate.

xy <- read.table(text = "Subject Product
1   ProdA
1   ProdB
1   ProdC
2   ProdB
2   ProdC
2   ProdD
3   ProdA
3   ProdB", header = TRUE)

aggregate(Product ~ Subject, FUN = paste, collapse = ";", data = xy)

  Subject           Product
1       1 ProdA;ProdB;ProdC
2       2 ProdB;ProdC;ProdD
3       3       ProdA;ProdB

将 R Dataframe 从长格式转换为宽格式并连接字符串值

Convert R Dataframe from long to wide format and concatenate string values

r

reshape