组 1 的结果类型``在 dplyr mutate 中使用因子时出错

Question

以下代码向我抛出了一个错误：

dfTest <- structure(list(Year = c(2018, 2018, 2018, 2018, 2018, 2018, 2018, 
                        2018, 2018, 2018, 2018, 2019, 2019, 2019, 2019, 2019, 2019, 2019, 
                        2019, 2019, 2019, 2019, 2020, 2020, 2020, 2020, 2020, 2020, 2020, 
                        2020, 2020, 2020, 2020, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 
                        2021, 2021, 2021, 2021)),
          class = c("grouped_df", "tbl_df", "tbl", "data.frame"),
          row.names = c(NA, -44L),
          groups = structure(list(
            Year = c(2018, 2019, 2020, 2021), 
            .rows = structure(list( 1:11, 12:22, 23:33, 34:44),
                              ptype = integer(0), class = c("vctrs_list_of", "vctrs_vctr", "list"))),
            class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, -4L), .drop = TRUE))

dfTest %>% mutate(Year = factor(Year, ordered = T))

错误是

Error in `mutate()`:
! Problem while computing `Year = factor(Year, ordered = T)`.
Caused by error:
! `Year` must return compatible vectors across groups.
ℹ Result type for group 1 (Year = 2018): <ordered<a0764>>.
ℹ Result type for group 2 (Year = 2019): <ordered<4e60d>>.
Run `rlang::last_error()` to see where the error occurred.

我没有立即在网上找到答案，所以我认为这可能会引起社区的兴趣。

Answer 1

这里的问题似乎是尝试对grouped变量使用factor函数会导致错误。 只需添加一个ungroup步骤即可解决问题：

dfTest <- structure(list(Year = c(2018, 2018, 2018, 2018, 2018, 2018, 2018, 
                        2018, 2018, 2018, 2018, 2019, 2019, 2019, 2019, 2019, 2019, 2019, 
                        2019, 2019, 2019, 2019, 2020, 2020, 2020, 2020, 2020, 2020, 2020, 
                        2020, 2020, 2020, 2020, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 
                        2021, 2021, 2021, 2021)),
          class = c("grouped_df", "tbl_df", "tbl", "data.frame"),
          row.names = c(NA, -44L),
          groups = structure(list(
            Year = c(2018, 2019, 2020, 2021), 
            .rows = structure(list( 1:11, 12:22, 23:33, 34:44),
                              ptype = integer(0), class = c("vctrs_list_of", "vctrs_vctr", "list"))),
            class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, -4L), .drop = TRUE))

dfTest %>%
ungroup %>%
mutate(Year = factor(Year, ordered = T))