绘制光谱轮廓——四个土地分类光谱轮廓绘制

问题遇到的现象和发生背景

请问大家这个怎么处理哇，完全看不懂。

问题相关代码，请勿粘贴截图

profiles <- df %>%

as.data.frame() %>%
cbind(., training_points$id) %>%
rename(id = "training_points$id") %>%
na.omit() %>%
group_by(id) %>%
summarise(band1 = mean(band1),
```
        band2 = mean(band2),
```
```
        band3 = mean(band3),
```
```
        band4 = mean(band4),
```
```
        band5 = mean(band5),
```
```
        band6 = mean(band6),
```
```
        band7 = mean(band7),
```
```
        band8 = mean(band8),
```
```
        band9 = mean(band9),
```
```
        band10 = mean(band10),
```
```
        band11 = mean(band11)) %>% 
```
mutate(id = case_when(id == 1 ~ "clouds",

                    id == 2 ~ "developed",

                    id == 3 ~ "undeveloped",

                    id == 4 ~ "water")) %>%

as.data.frame()

运行结果及报错内容

Error in (function (cond) :
error in evaluating the argument 'x' in selecting a method for function 'as.data.frame': Problem while computing band3 = mean(band3).
✖ band3 must be a vector, not a RasterLayer object.
ℹ The error occurred in group 1: id = 1.

我的解答思路和尝试过的方法

as.data.frame()，这个括号里要填东西吗？

我想要达到的结果

代码是课本上的还是你自己写的