Question

我编写了一个计算BMI的函数，并拥有创建相应图形输出的代码。我的目标是将图形输出包含到函数中，以便通过使用函数获得绘图。

我目前的代码：

BMI <- function(meter, kg){
  BMI <- kg/(meter^2)
  return(BMI)
}
BMI(1.8,70)

x <- seq(1.5, 1.9, by = 0.001)
y <- seq(30, 200, by = 0.5)
z <- outer(x, y, FUN = function(x, y) {BMI(x, y)})
contour(x, y, z, nlevels = 10, method = "edge", main = "BMI")
abline(h = 70, v=1.8, col="darkgrey") 
points(1.8,70, col="red", cex=2, pch=16, bg="red")

只需修改仪表＆amp;函数中的kg我希望得到一个具有正确线和点定位的图表。我从下面的代码开始 - 但是它不起作用。

graphicalBMI <- function(meter, kg){
  BMI <- kg/(meter^2)
  x <- seq(1.5, 1.9, by = 0.001)
  y <- seq(30, 200, by = 0.5)
  z <- outer(x, y, FUN = function(x, y) {graphicalBMI(x, y)})
  contour(x, y, z, nlevels = 10, method = "edge", main = "BMI")
  abline(h = kg, v= meter, col="darkgrey") 
  points(meter, kg, col="red", cex=2, pch=16, bg="red")
  return(graphicalBMI)
}

Answer 1

你的第二个功能的问题是它产生无限递归如果你这样改变你就会得到你想要的东西：

graphicalBMI <- function(meter, kg, showPlot=TRUE){

  BMI <- kg/(meter^2)

  if(showPlot){
    x <- seq(1.5, 1.9, by = 0.001)
    y <- seq(30, 200, by = 0.5)

    # here we call graphicalBMI by setting showPlot=F to avoid infinite recursion
    z <- outer(x, y, FUN = function(x, y) {graphicalBMI(x, y, FALSE)})
    contour(x, y, z, nlevels = 10, method = "edge", main = "BMI")
    abline(h = kg, v= meter, col="darkgrey") 
    points(meter, kg, col="red", cex=2, pch=16, bg="red")
  }
  return(BMI)
}


# usage example:
graphicalBMI(1.8,70) # plot produced

graphicalBMI(1.8,70,FALSE) # no plot produced

如何包含图形输出功能

1 个答案: