ggplot2绘图报错：object 'mass (gm)' not found 求助

问题背景 #

此前绘制MgNo的代码可正常运行：

MgNo_plot <- ggplot() +
  geom_point(data = MgNo_liq, aes(x = `T (C)`, y = MgNo), colour = "red") +
  geom_point(data = MgNo_Olv, aes(x = `T (C)`, y = MgNo), colour = "green") +
  geom_point(data = MgNo_Spn, aes(x = `T (C)`, y = MgNo), colour = "black") +
  geom_point(data = MgNo_Cpx, aes(x = `T (C)`, y = MgNo), colour = "purple")
print(MgNo_plot)

复制上述代码并修改绘图名称与y变量为mass (gm)后，运行出现报错：

Error in FUN(X[[i]], ...) : object 'mass (gm)' not found

经核对各数据框列名：MgNo_liq的对应列名为liq mass (gm)，其余数据框（MgNo_Olv、MgNo_Spn、MgNo_Cpx）的列名为mass (gm)，拼写与大小写均无误。

简单修复方案 #

方案1：单独指定MgNo_liq的y列名 #

直接在对应geom_point的aes中，为MgNo_liq指定正确的列名liq mass (gm)，其余部分保持不变：

mass_plot <- ggplot() +
  geom_point(data = MgNo_liq, aes(x = `T (C)`, y = `liq mass (gm)`), colour = "red") +
  geom_point(data = MgNo_Olv, aes(x = `T (C)`, y = `mass (gm)`), colour = "green") +
  geom_point(data = MgNo_Spn, aes(x = `T (C)`, y = `mass (gm)`), colour = "black") +
  geom_point(data = MgNo_Cpx, aes(x = `T (C)`, y = `mass (gm)`), colour = "purple")
print(mass_plot)

方案2：临时重命名MgNo_liq的列（不修改原数据） #

若希望保持所有geom_point的aes参数一致，可使用dplyr::rename临时将MgNo_liq的liq mass (gm)列重命名为mass (gm)，无需修改原始数据框：

library(dplyr)
mass_plot <- ggplot() +
  geom_point(data = MgNo_liq %>% rename(`mass (gm)` = `liq mass (gm)`), aes(x = `T (C)`, y = `mass (gm)`), colour = "red") +
  geom_point(data = MgNo_Olv, aes(x = `T (C)`, y = `mass (gm)`), colour = "green") +
  geom_point(data = MgNo_Spn, aes(x = `T (C)`, y = `mass (gm)`), colour = "black") +
  geom_point(data = MgNo_Cpx, aes(x = `T (C)`, y = `mass (gm)`), colour = "purple")
print(mass_plot)

内容的提问来源于stack exchange，提问作者Umbra077