使用带有变量r的表达式

I am trying to label a plot with the following label:

我试图用以下标签标记一个情节：

"Some Assay EC50 (uM)" where the "u" is a micro symbol.

“一些分析EC50（uM）”，其中“u”是微观符号。

I currently have:

我目前有：

assay <- "Some Assay"
plot(0,xlab=expression(paste(assay," AC50 (",mu,"M)",sep="")))

But that gives: "assay EC50 (uM)" rather than the desired "Some Assay EC50 (uM)".

但这给出了：“测定EC50（uM）”而不是所需的“某些测定EC50（uM）”。

Suggestions? Thanks.

建议？谢谢。

I also tried:

我也尝试过：

paste(assay,expression(paste(" AC50 (",mu,"M)",sep="")),sep="")

3 个解决方案

#1

You want a combination of bquote() and a bit of plotmath fu:

你想要bquote（）和一些plotmath fu的组合：

assay <- "Some Assay"
xlab <- bquote(.(assay) ~ AC50 ~ (mu*M))
plot(0, xlab = xlab)

The ~ is a spacing operator and * means juxtapose the contents to the left and right of the operator. In bquote(), anything wrapped in .( ) will be looked up and replaced with the value of the named object; so .(assay) will be replaced in the expression with Some Assay.

〜是间距运算符，*表示将内容并置到运算符的左侧和右侧。在bquote（）中，将查找包含在。（）中的任何内容并替换为命名对象的值;所以。（化验）将被表达式替换为Some Assay。

#2

another option using mtext and bquote

使用mtext和bquote的另一种选择

plot(0,xlab='')
Lines <- list(bquote(paste(assay," AC50 (",mu,"M)",sep="")))
mtext(do.call(expression, Lines),side=1,line=3)

Note that I set the xlab to null in the first plot.

请注意，我在第一个图中将xlab设置为null。

EDIT No need to call expression, since bquote will create an expression with replacement of elements wrapped in .( ) by their value. So a goodanswer is :

编辑无需调用表达式，因为bquote将创建一个表达式，用它们的值替换。（）中包含的元素。所以好的方面是：

plot(0,xlab='')
Lines <- bquote(paste(.(assay)," AC50 (",mu,"M)",sep=""))
mtext(Lines,side=1,line=3)

#3

You also could try the poor man's approach:

你也可以试试穷人的方法：

assay <- "Some Assay"
plot(0, xlab = paste0(assay, " AC50 (µM)"))

It specifies the mu character directly rather than using expressions (and paste0 is just paste with sep = "").

它直接指定mu字符而不是使用表达式（而paste0只是用sep =“”粘贴）。

#1