model.matrix Error: $ operator is invalid for atomic vectors

Question

我运行在使用'model.matrix'时遇到这个错误。

data_A <- data.frame(X1 = c("Y","N"), X2 = c(20,24), Y = c("N","Y"))
data_A
model.matrix("Y ~ X1 + X2", data_A)
Error: $ operator is invalid for atomic vectors

导致问题的原因是什么？

Answer 1

检查 ?model.matrix。一个片段：

     ## Default S3 method:
     model.matrix(object, data = environment(object),
                  contrasts.arg = NULL, xlev = NULL, ...)

Arguments:

  object: an object of an appropriate class.  For the default method, a
          model formula or a ‘terms’ object.

您的 object 是字符串公式，而 data 是 data_A。 object 参数应该是规定的公式或术语对象。尝试

model.matrix(Y ~ X1 + X2, data_A)

或等价地（如果您从字符串构造公式）

model.matrix(as.formula(Y ~ X1 + X2), data_A)

model.matrix Error: $ operator is invalid for atomic vectors

model.matrix Error: $ operator is invalid for atomic vectors

r

operator-keyword

model.matrix