如何将相关图表保存到 object？

Question

I'd like to make a correlation plot and save it to an object in a list.

I'm using a function and it appears to run the plot any time the function runs, so it's hard to save it to an object.

I could use record output, but I don't want it to show up at all. This is under the hood in a function, so I want to assign it to an object without having it run.

This is my code

library(fpp)
library(PerformanceAnalytics)
l <- list()  

l[["element"]] <-
  chart.Correlation(credit, 
                histogram = TRUE, 
                pch = 19)

l$element

I want to load the correlation plot when I run l$element, but not when I assign it to l[["element"]]

Answer 1

This is a little complex, because there is no "plot object". The call to chart.Correlation simply calls a bunch of drawing routines. It's not like a ggplot where the information to recreate the plot is stored as an object. In fact, the chart.Correlation function silently returns NULL .

If you want l$element to produce the plot, then you need to store the call to produce the plot inside l$element , and ensure that this call is evaluated when you type l$element into the console. Probably the easiest way to do this is to create a little wrapper around chart.Correlation with your own S3 class, whose print method eval s the call:

library(fpp)
library(PerformanceAnalytics)
l <- list()  

make_corrChart <- function(...) {
  mc <- match.call()
  mc[[1]] <- quote(chart.Correlation)
  structure(list(call = mc), class = "CorrChart")
}

print.CorrChart <- function(x, ...) eval(x$call)

l[["element"]] <-  make_corrChart(credit, histogram = TRUE, pch = 19)

Note that no plot is created at this point, but all the information needed to create the plot is stored in l$element . So when I type:

l$element

In the console, I get this: