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我创建了一个闪亮的应用程序，用户可以在其中加载文件并将对象用作函数参数。我还打印代码以在本地运行该函数（以便我或其他任何人可以复制和粘贴以重现结果）。

我想做的是能够使用类似dput但将加载对象的文本表示保存到对象而不是控制台。dput输出到控制台，但只是返回它的第一个参数的副本。我可以使用deparse，但是当对象的长度超过 width.cutoff（默认 60 和最大 500）时它会失败。

以下骇人听闻的可重现示例说明了这一点。在其中我image用作示例函数。就我而言，我还有其他带有更多参数的函数。

#create example matrices
m2 <- matrix(1:4,2,2)
m4 <- matrix(1:4,4,4)

#this is what I want to recreate
image(z=m2,col=rainbow(4))
image(z=m4,col=rainbow(4))

#convert the matrices to their text representation
txtm2 <- deparse(m2)
txtm4 <- deparse(m4)

#create a list of arguments
lArgs2 <- list( z=txtm2, col=rainbow(4) )
lArgs4 <- list( z=txtm4, col=rainbow(4) )

#construct arguments list
vArgs2 <- paste0(names(lArgs2),"=",lArgs2,", ")
vArgs4 <- paste0(names(lArgs4),"=",lArgs4,", ")

#remove final comma and space
vArgs2[length(vArgs2)] <- substr(vArgs2[length(vArgs2)],0,nchar(vArgs2[length(vArgs2)])-2)
vArgs4[length(vArgs4)] <- substr(vArgs4[length(vArgs4)],0,nchar(vArgs4[length(vArgs4)])-2)

#create the text function call
cat("image(",vArgs2,")")
cat("image(",vArgs4,")")

#the 1st one when pasted works
image( z=structure(1:4, .Dim = c(2L, 2L)),  col=c("#FF0000FF", "#80FF00FF", "#00FFFFFF", "#8000FFFF") )

#the 2nd one gives an error because the object has been split across multiple lines
image( z=c("structure(c(1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, ", "2L, 3L, 4L), .Dim = c(4L, 4L))"),  col=c("#FF0000FF", "#80FF00FF", "#00FFFFFF", "#8000FFFF") )

#In an ideal world I would also like it to work when I did this, but maybe that's asking too much
image(z=txtm2,col=rainbow(4))

我意识到我构造函数调用的方式是一种 hack，但是当我前一段时间查看它时，我找不到更好的方法。接受任何建议。谢谢。

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1 回答 1

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您可以执行以下操作：

## an object that you want to recreate
m2 <- matrix(1:4,2,2)
## use capture.output to save structure as a string in a varible
xx <- capture.output(dput(m2))

## recreate the object 
m2_ <- eval(parse(text=xx))
image(z=m2_,col=rainbow(4))
于 2014-10-09T11:13:42.693 回答