使用R打印环境

Question

我想编写一个函数，其输出是类myclass的对象，带有vector，list，integer等等。与lmfunction类似。我试图使用environment，但是当我打印函数值时，结果是

#Term 1
> fit1
<environment: 0x00000000220d1998>
attr(,"class")
[1] "myclass"

但是，当我打印lm函数时，结果是

> fit2
Call:
lm(formula = variable1 ~ variable2)

Coefficients:
     (Intercept)         variable2  
         49.0802            0.3603 

我知道使用environment访问$的各个值。但我希望打印的对象与lm函数相同，如图所示。

Answer 1

那是你要的吗？

variable1 <- rnorm(10)
variable2 <- rnorm(10)
fit1 <- lm(variable1~variable2)
fit2 <- fit1
class(fit2) <- "myclass"

# have a look at stats:::print.lm
# and copy that function, hence define it as print method for your class or edit further:
print.myclass <- function (x, digits = max(3L, getOption("digits") - 3L), ...) {
  cat("\nCall:\n", paste(deparse(x$call), sep = "\n", collapse = "\n"), 
      "\n\n", sep = "")
  if (length(coef(x))) {
    cat("Coefficients:\n")
    print.default(format(coef(x), digits = digits), print.gap = 2L, 
                  quote = FALSE)
  }
  else cat("No coefficients\n")
  cat("\n")
  invisible(x)
}

# now print
print(fit2)

# or
fit2