如果无错误的 R 函数不这样做，如何 return 一个值

Question

我的目标是将 pyramid package 生成的情节分配给列表。稍后，我会将列表中的该图和其他图插入到文档中。但是 pyramid function 似乎不是 return 一个值。如何将金字塔图分配给对象？

install.packages("pyramid") # functions to draw a population pyramid
library(pyramid)

# create a mock data frame to comparing this plot to a counterpart from plotrix

df <- data.frame(level1 = c(9,9,4,3,34,28), levelsame = c(9,9,4,3,34,28),
 title = c("Dir", "Exec. Dir", "Mgr", "Sr. Mgr", "Mgt Princ", "EVP+"))

        # assign the plot (hopefully) to an object
empty <- pyramid(df, Laxis = seq(1,35,5), AxisFM = "g", Csize = 0.8, Cgap = .5, Llab = "",
                                 Rlab = "", Clab = "Title", GL = F, Lcol = "blue", Rcol = "blue",
                                 Ldens = -1, main = "Distribution of Levels")

> empty
NULL

同样，如果我将 pyramid call 分配到我的列表中，则什么也不会发生。 pyramid 编辑的 return 列表没有值。

plotlist2[["pyramid"]] <-  pyramid(df, Laxis = seq(1,35,5), AxisFM = "g", Csize = 0.8, Cgap = .5, Llab = "",
                                  Rlab = "", Clab = "Title", GL = F, Lcol = "blue", Rcol = "blue",
                                  Ldens = -1, main = "Distribution of Levels")
> plotlist2[1]
[[1]]
NULL

我担心我在一些明显的误解中犯了错误，所以我欢迎被纠正。谢谢。

Answer 1

您可以使用recordPlot()函数将当前绘图保存到变量。

在你的情况下你可以这样做：

#print the plot
pyramid(df, Laxis = seq(1,35,5), AxisFM = "g", Csize = 0.8, Cgap = .5, Llab = "",
        Rlab = "", Clab = "Title", GL = F, Lcol = "blue", Rcol = "blue",
        Ldens = -1, main = "Distribution of Levels")

#save the current printed plot
pyrPlot<-recordPlot()

#plot it again
pyrPlot

您可能必须使用 dev.control(displaylist ="enable") 启用显示列表才能正常工作，具体取决于您使用的图形设备

如果无错误的 R 函数不这样做，如何 return 一个值

How to return a value if an error-free R function does not do so

null

r

function

return-value