r - ggplot 图例标签内的希腊字母、符号和换行符

Question

我在尝试着

有换行符(自动或强制)

对齐文本(左对齐或左右对齐)

有希腊字母和百分号

在 gglot 图例标签内。

我尝试了几种方法，但我似乎无法结合我读到的所有技巧。

我可以通过插入 \n 来获得换行符进入标签，但这似乎不适用于希腊字母，不适用于图例标签。或者我可以通过组合 mtext() 在基本图中使用换行符和希腊字母和 bquote()将一段文本插入到图中，( 编辑 )但正如 Gregor 在评论部分指出的那样，这不适用于 ggplot .下面我结合一个 list与 paste0()将文本传递给图例标签:问题是我找不到插入希腊字母的方法，例如 Gamma 。

感谢您的建议。

这是我尝试的 MWE( 编辑: 改进的 MWE):

label1.line1 <- "Not much to say about this one"
label2.line1 <- "blabla blabla, blabla blabla, blee blee blee (bling, bling, bling),"
label2.line2 <- paste0("(", "1900-2014: g = 1.50%, gamma = 2.75%, and r = 2.30%",")")
label3.line1 <- "blabla blabla, blabla blabla, blee blee blee (bling, bling, bling),"
label3.line2 <- paste0("(", "1900-2014: g = 2.50%, gamma = 1.75%, and r = 2.30%",")")
labels_fixed <- list(
    label1.line1, 
    paste0(label2.line1, "\n", label2.line2),
    paste0(label3.line1, "\n", label3.line2)
)
library(ggplot2)
library(scales)
library(grid)  # provides unit() function used to tweak spacing inside legend

ggplot(data = mtcars, aes(x = mpg, y = wt, group = factor(cyl), colour = factor(cyl), shape = factor(cyl))) + 
geom_line() + geom_point(size = 3) + theme_bw() + 
scale_shape_manual(name = "Details", values = c(17, 21, 15), 
    labels = labels_fixed) + 
scale_colour_manual(name = "Details", values = c("darkred", "darkgreen", "darkblue"), 
    labels = labels_fixed) + 
theme(legend.key = element_blank(), 
      legend.position = c(.65, .8), 
      legend.background = element_rect(colour = "black"), 
      legend.key.size = unit(2, "lines"), 
      legend.text = element_text(size = 15)) 

一个小问题是多行的图例文本要小得多，因此需要调整图例行距:我能够调整 legend.key.size和 legend.text以获得比默认值更好的结果，这太局促了。

我还尝试了另一个涉及 cat(strwrap("long label here"), sep = "\n") 的建议，但我无法让它发挥作用。我也试过 atop但这使得每行都太小，并且实现所需堆叠所需的嵌套很乏味。

有没有办法得到希腊字母？



以下是一些我无法发挥作用的有用建议，例如 mtext()的组合和 bquote()在1和2中提到:

Expression and new line in plot labels

Line break in expression()?

Wrap horizontal legend across multiple rows

using expression(paste( to insert math notation into a ggplot legend

ggplot2 two-line label with expression

How to annotate() ggplot with latex

Greek letters in ggplot annotate

Answer 1

Baptiste 的建议是正确的:unicode 大有帮助。用 \u03B3 替换上面的每个 gamma 实例它将显示为希腊语。惊人的!
打印可以通过 cairo 完成设备 ( ref ):

library(Cairo)
cairo_pdf(file = "ggplot-greek.pdf", width = 8, height = 5)
## ggplot object created here
dev.off()

也适用: ggsave("greek.pdf", device = cairo_pdf)以下是我发现有用的 unicode 符号选择:

"\U016B" = ū
"\U016A" = Ū
"\U00FB" = û
"\U00DB" = Û
"\U0233" = ȳ
"\U0232" = Ȳ
"\U0177" = ŷ
"\U0176" = Ŷ
"\U0113" = ē
"\U0112" = Ē
"\u00EA" = ê
"\U00CA" = Ê
"\U003BC\U2080" = μ₀
"\U003BC\U2081" = μ₁
"R\U00B2" = R²
"\u221E" = ∞
"\u2248" = ≈
"\U2260" = ≠ 
"\u03C3/\u221An" = σ/√n

遗憾的是，并非所有特殊字符都具有 unicode 等效项。例如，y-hat 有一个 unicode，但 x-hat 没有。可以将字母 x 与 Unicode 条组合，如 "x\u0305" = x̅或 "p\u0302" = p̂ ，但这似乎不太好打印。
我也很难将希腊 unicode 打印为轴标签，因此在这些情况下我求助于 annotate()带有选项 coord_cartesian(clip = "off")确保轴下方打印的标签不会被剪裁(“on”是默认剪裁行为)。
有时您可以直接使用该字符，例如:

myplot + labs(title  = "±")

当unicode失败时，你可以试试 expression() ，例如 x̄ :

title = expression(paste("z = (", bar(x), "-\u03BC)/(\u03C3/\u221An)", sep = ""))  
library(ggplot2)
ggplot() + labs(title = title) + theme_bw() 

为方便起见，我在下面复制了一些常用的希腊字母的 unicode。可以找到更多的 unicode，例如 http://en.wikipedia.org/wiki/List_of_Unicode_characters

\u0391  Α   Greek Capital Letter Alpha
\u0392  Β   Greek Capital Letter Beta
\u0393  Γ   Greek Capital Letter Gamma
\u0394  Δ   Greek Capital Letter Delta
\u0395  Ε   Greek Capital Letter Epsilon
\u0396  Ζ   Greek Capital Letter Zeta
\u0397  Η   Greek Capital Letter Eta
\u0398  Θ   Greek Capital Letter Theta
\u0399  Ι   Greek Capital Letter Iota
\u039A  Κ   Greek Capital Letter Kappa
\u039B  Λ   Greek Capital Letter Lambda
\u039C  Μ   Greek Capital Letter Mu
\u039D  Ν   Greek Capital Letter Nu
\u039E  Ξ   Greek Capital Letter Xi
\u039F  Ο   Greek Capital Letter Omicron
\u03A0  Π   Greek Capital Letter Pi
\u03A1  Ρ   Greek Capital Letter Rho
\u03A3  Σ   Greek Capital Letter Sigma
\u03A4  Τ   Greek Capital Letter Tau
\u03A5  Υ   Greek Capital Letter Upsilon
\u03A6  Φ   Greek Capital Letter Phi
\u03A7  Χ   Greek Capital Letter Chi
\u03A8  Ψ   Greek Capital Letter Psi
\u03A9  Ω   Greek Capital Letter Omega
\u03B1  α   Greek Small Letter alpha
\u03B2  β   Greek Small Letter beta
\u03B3  γ   Greek Small Letter gamma
\u03B4  δ   Greek Small Letter delta
\u03B5  ε   Greek Small Letter epsilon
\u03B6  ζ   Greek Small Letter zeta
\u03B7  η   Greek Small Letter eta
\u03B8  θ   Greek Small Letter theta
\u03B9  ι   Greek Small Letter iota
\u03BA  κ   Greek Small Letter kappa
\u03BB  λ   Greek Small Letter lambda
\u03BC  μ   Greek Small Letter mu
\u03BD  ν   Greek Small Letter nu
\u03BE  ξ   Greek Small Letter xi
\u03BF  ο   Greek Small Letter omicron
\u03C0  π   Greek Small Letter pi
\u03C1  ρ   Greek Small Letter rho
\u03C2  ς   Greek Small Letter final sigma
\u03C3  σ   Greek Small Letter sigma
\u03C4  τ   Greek Small Letter tau
\u03C5  υ   Greek Small Letter upsilon
\u03C6  φ   Greek Small Letter phi
\u03C7  χ   Greek Small Letter chi
\u03C8  ψ   Greek Small Letter psi
\u03C9  ω   Greek Small Letter omega

有关哪些字体与 unicode 一起使用的信息: https://en.wikipedia.org/wiki/List_of_typefaces#Unicode_fonts
一些货币符号:

# http://www.fileformat.info/info/unicode/category/Sc/list.htm
Character   Name    Browser     Image
\u0024  DOLLAR SIGN     $
\u00A2  CENT SIGN   ¢
\u00A3  POUND SIGN  £
\u00A4  CURRENCY SIGN   ¤
\u00A5  YEN SIGN    ¥
\u058F  ARMENIAN DRAM SIGN
\u060B  AFGHANI SIGN    ؋
\u09F2  BENGALI RUPEE MARK  ৲
\u09F3  BENGALI RUPEE SIGN  ৳
\u09FB  BENGALI GANDA MARK
\u0AF1  GUJARATI RUPEE SIGN     ૱
\u0BF9  TAMIL RUPEE SIGN    ௹
\u0E3F  THAI CURRENCY SYMBOL BAHT   ฿
\u17DB  KHMER CURRENCY SYMBOL RIEL  ៛
\u20A0  EURO-CURRENCY SIGN  ₠
\u20A1  COLON SIGN  ₡
\u20A2  CRUZEIRO SIGN   ₢
\u20A3  FRENCH FRANC SIGN   ₣
\u20A4  LIRA SIGN   ₤
\u20A5  MILL SIGN   ₥
\u20A6  NAIRA SIGN  ₦
\u20A7  PESETA SIGN     ₧
\u20A8  RUPEE SIGN  ₨
\u20A9  WON SIGN    ₩
\u20AA  NEW SHEQEL SIGN     ₪
\u20AB  DONG SIGN   ₫
\u20AC  EURO SIGN   €
\u20AD  KIP SIGN    ₭
\u20AE  TUGRIK SIGN     ₮
\u20AF  DRACHMA SIGN    ₯
\u20B0  GERMAN PENNY SIGN   ₰
\u20B1  PESO SIGN   ₱
\u20B2  GUARANI SIGN    ₲
\u20B3  AUSTRAL SIGN    ₳
\u20B4  HRYVNIA SIGN    ₴
\u20B5  CEDI SIGN   ₵
\u20B6  LIVRE TOURNOIS SIGN     ₶
\u20B7  SPESMILO SIGN   ₷
\u20B8  TENGE SIGN  ₸
\u20B9  INDIAN RUPEE SIGN   ₹
\u20BA  TURKISH LIRA SIGN   ₺
\u20BB  NORDIC MARK SIGN    ₻
\u20BC  MANAT SIGN  ₼
\u20BD  RUBLE SIGN  ₽
\uA838  NORTH INDIC RUPEE MARK
\uFDFC  RIAL SIGN   ﷼
\uFE69  SMALL DOLLAR SIGN   ﹩
\uFF04  FULLWIDTH DOLLAR SIGN   ＄
\uFFE0  FULLWIDTH CENT SIGN     ￠
\uFFE1  FULLWIDTH POUND SIGN    ￡
\uFFE5  FULLWIDTH YEN SIGN  ￥
\uFFE6  FULLWIDTH WON SIGN