发送包含双引号的文本字符串到function

I'm having a problem with using double quotes while formatting text strings being sent to functions in R.

在格式化发送到R中的函数的文本字符串时，我遇到使用双引号的问题。

Consider an example function code:

考虑一个示例功能代码：

foo <- function( numarg = 5, textarg = "** Default text **" ){ 
    print (textarg)
    val <- numarg^2 + numarg
    return(val) 
}

when running with the following input:

使用以下输入运行时：

foo( 4, "Learning R is fun!" )

The output is:

输出是：

[1] "Learning R is fun!"
[1] 20

But when I try (in various ways, as suggested here) to write "R" instead of R, I get the following outputs:

但是当我尝试（以各种方式，如此处所建议的）写“R”而不是R时，我得到以下输出：

> foo( 4, "Learning R is fun!" )
[1] "Learning R is fun!"
[1] 20
> foo( 4, "Learning "R" is fun!" )
Error: unexpected symbol in "funfun( 4, "Learning "R"
> foo( 4, "Learning \"R\" is fun!" )
[1] "Learning \"R\" is fun!"
[1] 20
> foo( 4, 'Learning "R" is fun!' )
[1] "Learning \"R\" is fun!"
[1] 20

Using as.character(...) or dQuote(...) as suggested here seems to break the function because of different number of arguments.

使用as.character（...）或dQuote（...）这里建议似乎打破了函数，因为参数数量不同。

2 个解决方案

#1

You can try these approaches:

您可以尝试以下方法：

foo <- function(numarg = 5, textarg = "** Default text **" ){ 
    cat(c(textarg, "\n")) 
    val <- (numarg^2) + numarg
    return(val) 
}

foo <- function(numarg = 5, textarg = "** Default text **" ){ 
    print(noquote(textarg)) 
    val <- (numarg^2) + numarg
    return(val) 
}

foo( 4, "Learning R is fun!" )
foo( 4, 'Learning "R" is fun!' )

#2

Two ways I know. First is to just use single quotes to start and end the character string:

我知道两种方式。首先是使用单引号来开始和结束字符串：

> cat( 'Learning "R" is fun!' )
Learning "R" is fun!

Second is to escape the double quotes:

第二是逃避双引号：

> cat( "Learning \"R\" is fun!" )
Learning "R" is fun!

Note that this works because I use cat, which is intended to output strings to the console. It seems you use print() which shows the object rather than output it

请注意，这是有效的，因为我使用cat，它旨在将字符串输出到控制台。看来你使用print（）来显示对象而不是输出它

#1