非常好的问题.谢谢！

这里我们使用:

1. rowSums 添加一列，行和为 X1-X3
2. 然后我们mutate 跨所有X和
3. coalesce 每个 X 与 rowSum1
4. 令人惊讶的是 rowSum1 列因为不需要而消失了 ->
5. 这是由于 .keep="unused" 的 mutate
参数

1. rowSums to add a column with the row sums of X1-X3
2. then we mutate across all X and
3. coalesce each X with rowSum1
4. surprisingly rowSum1 column is gone away because not needed ->
5. this is due to the fantastic .keep="unused" argument of mutate

library(tidyverse)
df %>% 
  mutate(rowsum1 = rowSums(select(., starts_with("X")), na.rm=TRUE)) %>% 
  mutate(across(starts_with("X"), ~coalesce(.,rowsum1)),.keep="unused")

输出:

  ID       X1    X2    X3
  <chr> <dbl> <dbl> <dbl>
1 A      0.96  1.93  0.97
2 B      1     2.01  1.01
3 C      0.98  0.03  1.01
4 A      1     2     1   
5 D      1.04  0.05  0.99