R 沿两个分组变量排序

我想使用

row\u number（）

沿两个变量生成一个序列，但结果并不像我预期的那样

library(tidyverse)
#> Warning: package 'tidyverse' was built under R version 3.6.3
#> Warning: package 'ggplot2' was built under R version 3.6.3
#> Warning: package 'tibble' was built under R version 3.6.3
#> Warning: package 'tidyr' was built under R version 3.6.2
#> Warning: package 'purrr' was built under R version 3.6.2
#> Warning: package 'dplyr' was built under R version 3.6.3
#> Warning: package 'forcats' was built under R version 3.6.3
test <- data.frame(model = c("iron", "iron", "iron", "steel", "steel"), year = c(2010, 2011, 2012, 2008, 2009))
test %>% group_by(model, year) %>% mutate(number = row_number())
#> # A tibble: 5 x 3
#> # Groups:   model, year [5]
#>   model  year number
#>   <fct> <dbl>  <int>
#> 1 iron   2010      1
#> 2 iron   2011      1
#> 3 iron   2012      1
#> 4 steel  2008      1
#> 5 steel  2009      1

---

如何实现此结果？

如果按列对u进行分组，R将为每个列创建一个“分区”，在每个分区内，行号将递增。从预期输出来看，似乎不需要分组

> df %>% mutate(number = row_number())
  model year number
1  iron 2010      1
2  iron 2011      2
3  iron 2012      3
> 

然后，您希望仅根据模型进行分组：

> test %>% group_by(model) %>% mutate(number = row_number())
# A tibble: 5 x 3
# Groups:   model [2]
  model  year number
  <chr> <dbl>  <int>
1 iron   2010      1
2 iron   2011      2
3 iron   2012      3
4 steel  2008      1
5 steel  2009      2
> 

>test%>%group\u by（model）%>%mutate（number=row\u number（））
#一个tibble:5x3
#分组：模型[2]
车型年款
1铁2010 1
2铁2011 2
3铁2012 3
4钢铁2008 1
5钢铁2009 2
> 

谢谢。我在我的例子中犯了一个错误。我更新了我的问题来说明我为什么需要分组。更新了答案，对你有用吗？

> test %>% group_by(model) %>% mutate(number = row_number())
# A tibble: 5 x 3
# Groups:   model [2]
  model  year number
  <chr> <dbl>  <int>
1 iron   2010      1
2 iron   2011      2
3 iron   2012      3
4 steel  2008      1
5 steel  2009      2
>