R：如何从scale\u fill\u manual（）调用中获取ScaleDiscrete对象的字符表示形式，以便在ggplot2中正确解析

我的问题的数据集：

set.seed(1)
dfr2 <- tibble(x1 = factor(sample(letters[1:3], 50, replace = T), levels=letters[1:3]),
             x2 = factor(sample(letters[1:2], 50, replace = T), levels=letters[1:2]),
             x3 = factor(sample(letters[1:3], 50, replace = T), levels=letters[1:3]),
             grpA = factor(sample(c("grp1","grp2"),50, prob=c(0.3, 0.7) ,replace=T), levels = c("grp1", "grp2")),
             grpB = factor(sample(c("grp1","grp2"),50, prob=c(0.6, 0.4) ,replace=T), levels = c("grp1", "grp2"))
             )

head(dfr2)

为三级因子（“x1”、“x3”）和二级因子（“x2”）创建自定义颜色比例：

在色阶的字符串表示形式上调用class函数会显示这些对象是字符对象：

class(col_scales2[1])
class(col_scales2[2])

因此，它们是不相同的：

identical(factor_3lev_col_scale, col_scales2[1])
identical(factor_2lev_col_scale, col_scales2[2])

当我尝试将自定义颜色比例的字符串表示形式指定给“col_scal”，然后将“col_scal”与ggplot2:：ggplot（）一起使用时，它失败了：

for(gvar in names(dfr2)[4]){
  for(mvar in names(dfr2)[1:3])  {
    
    if (mvar %in% names(dfr2[c(1,3)])) {
      col_scal <- col_scales2[1]
    } else {
      col_scal <- col_scales2[2]
    }   
    print(ggplot(plot_data_prepr(dfr2, gvar, mvar),
                 aes(x = !!sym(mvar), y = pct2, fill = !!sym(mvar))) +
      geom_bar(stat = 'identity') +
      ylim(0,1) +
      geom_text(aes(label=pct_lab, y = pct_pos + .02)) +
      col_scal +  
      facet_grid(as.formula(paste0(".~", gvar))) +
      ggtitle(paste0(mvar, " by ", gvar)))
  }
}

for（名称中的gvar（dfr2）[4]）{
用于（名称中的mvar（dfr2）[1:3]）{
如果（mvar%在%名称中（dfr2[c（1,3）]）{
请用这个。它很好用

if (mvar %in% names(dfr2[c(1,3)])) {
      col_scal <- eval_tidy(as.name(col_scales2[2]))
    } else {
      col_scal <- eval_tidy(as.name(col_scales2[1]))
    } 

if（mvar%in%names（dfr2[c（1,3）]）{
col_scal
class(factor_3lev_col_scale)
class(factor_2lev_col_scale)


class(col_scales2[1])
class(col_scales2[2])


identical(factor_3lev_col_scale, col_scales2[1])
identical(factor_2lev_col_scale, col_scales2[2])


for(gvar in names(dfr2)[4]){
  for(mvar in names(dfr2)[1:3])  {
    
    if (mvar %in% names(dfr2[c(1,3)])) {
      col_scal <- col_scales2[1]
    } else {
      col_scal <- col_scales2[2]
    }   
    print(ggplot(plot_data_prepr(dfr2, gvar, mvar),
                 aes(x = !!sym(mvar), y = pct2, fill = !!sym(mvar))) +
      geom_bar(stat = 'identity') +
      ylim(0,1) +
      geom_text(aes(label=pct_lab, y = pct_pos + .02)) +
      col_scal +  
      facet_grid(as.formula(paste0(".~", gvar))) +
      ggtitle(paste0(mvar, " by ", gvar)))
  }
}


for(gvar in names(dfr2)[4]){
  for(mvar in names(dfr2)[1:3])  {
    
    if (mvar %in% names(dfr2[c(1,3)])) {
      col_scal <- factor_3lev_col_scale
    } else {
      col_scal <- factor_2lev_col_scale
    }   
    print(ggplot(plot_data_prepr(dfr2, gvar, mvar),
                 aes(x = !!sym(mvar), y = pct2, fill = !!sym(mvar))) +
      geom_bar(stat = 'identity') +
      ylim(0,1) +
      geom_text(aes(label=pct_lab, y = pct_pos + .02)) +
      col_scal +  
      facet_grid(as.formula(paste0(".~", gvar))) +
      ggtitle(paste0(mvar, " by ", gvar)))
  }
}


if (mvar %in% names(dfr2[c(1,3)])) {
      col_scal <- eval_tidy(as.name(col_scales2[2]))
    } else {
      col_scal <- eval_tidy(as.name(col_scales2[1]))
    }