r - 在多行中绘制图例标签，包括数学表达式

Question

如何创建包含多行文本的图例标签，后跟单独一行上的数学表达式，以避免下面列出的问题？

已接受的答案 here不适用于图例，据我所知，涉及 bquote 的替代答案也不适用于我的情况，如下所示。

可重现的代码:

# multiple lines in first legend label are not horizontally aligned
# also, entire legend label is not vertically aligned with box
plot( runif(10), runif(10) )
legend( x='top', fill=grey.colors(2), bty='n', ncol=2, inset=.1,
    legend=c( expression( "Hello world\nGoodbye world\n" ~ 64 %/% 8 %/% 8 ),
        'something else' ) )

# both above problems fixed, but math expression doesn't display right
plot( runif(10), runif(10) )
legend( x='top', fill=grey.colors(2), bty='n', ncol=2, inset=.1,
    legend=c( paste( "Hello world\nGoodbye world\n", expression( 64 %/% 8 %/% 8 ) ),
        'something else' ) )

# nested atops within bquote almost works in title, but font size is not uniform
# does not work at all in legend, anyway
plot( runif(10), runif(10) )
label1 = bquote( atop( atop( "Hello world", "Goodbye world" ), 64 %/% 8 %/% 8 ) )
labels = c( label1, 'something else' )
title( label1 )
legend( x='top', fill=grey.colors(2), bty='n', ncol=2, inset=.1, legend=labels )

Answer 1

一个选项是

plot( runif(10), runif(10) )
legend( x='top', fill=grey.colors(2), bty='n', ncol=2, inset=.1,
    legend=c( expression( atop("Hello world\nGoodbye world",64 %/% 8 %/% 8) ),
         'something else' ) )

或

plot( runif(10), runif(10) )
legend( x='top', fill=grey.colors(2), bty='n', ncol=2, inset=.1,
    legend=c( expression( atop(atop("Hello world","Goodbye world"),64 %/% 8 %/% 8) ),
         'something else' ) )

但 R 确实不喜欢在 ?plotmath 模式下使用换行符。如果您需要查找器控制图例，最好导出为 pdf 并在 Adob​​e Illustrator 等中进行精细编辑。