在 R 图的图例中插入数学符号

Question

我正在使用 survminer 生成具有 2 条生存曲线的生存曲线，一条用于在手术期间接受 4 个包装红细胞 (PRBC) 单位的患者，另一条用于接受超过 4 个 PRBC 单位的患者。不幸的是，我无法使用“表达式”或“bquote”函数将正确的“

我已阅读过有关此主题的先前帖子，但我使用 expression() 和 bquote() 找到的指导似乎无法正常工作。

library(survival)
library(coxed)
library(survminer)

simdata <- sim.survdata(N=300, T=100, num.data.frames=1, xvars = 1)

d <- simdata$data

d$Xfactor <- ifelse(d$X <= 0.3, 1, 0)


# the code chunks below do not seem to work because of the legends

ggsurvplot(
  fit = survfit(Surv(d$y, event = d$failed) ~ d$Xfactor, data = d), 
  xlab = "Years", 
  ylab = "Overall survival probability",
  main = "Overall survival",
  legend.labs = c(bquote(<= ~ "4 Units"),"> 4 Units"))

ggsurvplot(
  fit = survfit(Surv(d$y, event = d$failed) ~ d$Xfactor, data = d), 
  xlab = "Years", 
  ylab = "Overall survival probability",
  main = "Overall survival",
  legend.labs = c(bquote("" ~ <= ~ "4 Units"),"> 4 Units"))

ggsurvplot(
  fit = survfit(Surv(d$y, event = d$failed) ~ d$Xfactor, data = d), 
  xlab = "Years", 
  ylab = "Overall survival probability",
  main = "Overall survival",
  legend.labs = c(expression("",<=,"4 Units"),"> 4 Units"))

ggsurvplot(
  fit = survfit(Surv(d$y, event = d$failed) ~ d$Xfactor, data = d), 
  xlab = "Years", 
  ylab = "Overall survival probability",
  main = "Overall survival",
  legend.labs = c(expression(<=,"4 Units"),"> 4 Units"))

ggsurvplot(
  fit = survfit(Surv(d$y, event = d$failed) ~ d$Xfactor, data = d), 
  xlab = "Years", 
  ylab = "Overall survival probability",
  main = "Overall survival",
  legend.labs = c(expression(<= "4 Units"),"> 4 Units"))

Answer 1

要在字符串中放置 unicode 字符，您可以使用 unicode 数字作为要转义的符号 \u。即使用\u2265 表示≥，使用\u2264 表示≤。

ggsurvplot(
  fit = survfit(Surv(d$y, event = d$failed) ~ d$Xfactor, data = d), 
  xlab = "Years", 
  ylab = "Overall survival probability",
  main = "Overall survival",
  legend.labs = c("\u2264 4 Units","> 4 Units"))