等号更改 survfit 对象自动绘图中图例标签的渲染

我使用survival程序包按组对生存曲线进行Kaplan-Mayer估计，然后使用ggfortify和survminer程序包绘制出上述曲线.除用于打印的图例标签外，所有标签均工作正常.我想在图例标签中显示N个大小的组.我认为使用paste0将N大小添加到GROUPING变量本身是一个不错的方法.在我的情况下，它比使用像scale_fill_discrete("", labels = legend_labeller_for_plot)这样的东西更容易.

library(dplyr)
library(ggplot2)
library(survival)
library(survminer)
library(ggfortify)


set.seed = 100
data <- data.frame(
  time = rlnorm(20),
  event = as.integer(runif(20) < 0.5),
  group = ifelse(runif(20) > 0.5,
                 "group A",
                 "group B")
)

# Plotting survival curves without N sizes in the legend
fit <- survfit(
  with(data, Surv(time, event)) ~ group,
  data)

autoplot(fit)

# Adding N sizes to the data and plotting
data_new <- data %>% 
  group_by(group) %>% mutate(N = n()) %>% 
  ungroup() %>% 
  mutate(group_with_N = paste0(group, ", N = ", N))

fit_new <- survfit(
  with(data, Surv(time, event)) ~ group_with_N,
  data_new)

autoplot(fit_new)

When I try to add N sizes to the groups variable, the part with "N =" in the grouping variable disappears, i.e. the group variable isn't displayed on the legend labels as expected.

For comparison, what I expect is something like the following using Iris data:

更重要的是，我发现罪魁祸首是等号=.当我go 掉=号时，图例标签对应于分组变量值. 我的问题是，为什么等号会导致这种情况？