r - 如何在r中创 build 计矩阵

Question

我有两个因素。因子A有2个水平，因子B有3个水平。

如何创建以下设计矩阵？

     factorA1 factorA2 factorB1 factorB2 factorB3
[1,]        1        0        1        0        0
[2,]        1        0        0        1        0
[3,]        1        0        0        0        1
[4,]        0        1        1        0        0
[5,]        0        1        0        1        0
[6,]        0        1        0        0        1

Answer 1

你有几个选择:

使用底座并自己拼凑:

(iris.dummy<-with(iris,model.matrix(~Species-1))) 
(IRIS<-data.frame(iris,iris.dummy)) 

或者使用 ade4 包如下:

dummy <- function(df) {
    require(ade4)
    ISFACT <- sapply(df, is.factor)
    FACTS <- acm.disjonctif(df[, ISFACT, drop = FALSE])
    NONFACTS <- df[, !ISFACT,drop = FALSE]
    data.frame(NONFACTS, FACTS)
}

dat <-data.frame(eggs = c("foo", "foo", "bar", "bar"),  
    ham = c("red","blue","green","red"), x=rnorm(4)) 
dummy(dat)



##           x eggs.bar eggs.foo ham.blue ham.green ham.red
## 1 0.3365302        0        1        0         0       1
## 2 1.1341354        0        1        1         0       0
## 3 2.0489741        1        0        0         1       0
## 4 1.1019108        1        0        0         0       1