Question

我想重命名在dplyr中使用group_by创建的列。创建的名称是format(date2, "%Y-%m")，不是很有用。我尝试过几件事。我希望新名称是＆＃34; yrMth＆＃34;

    df <- data.frame(Person = c(rep("abc",3), rep("eee", 5)),
             date = c("4/1/2016", "4/3/2016", "4/12/2016", "5/3/2016", "5/4/2016","5/10/2016","5/6/2016", "5/11/2016"),
             account = c("123","123","123","222","222","333","222","333"), stringsAsFactors = F)

    df$date2 <- mdy(df$date)

    df %>%
      group_by(format(date2, "%Y-%m"))

  Person      date account      date2 `format(date2, "%Y-%m")`
   <chr>     <chr>   <chr>     <date>                    <chr>
1    abc  4/1/2016     123 2016-04-01                  2016-04
2    abc  4/3/2016     123 2016-04-03                  2016-04
3    abc 4/12/2016     123 2016-04-12                  2016-04
4    eee  5/3/2016     222 2016-05-03                  2016-05
5    eee  5/4/2016     222 2016-05-04                  2016-05
6    eee 5/10/2016     333 2016-05-10                  2016-05
7    eee  5/6/2016     222 2016-05-06                  2016-05
8    eee 5/11/2016     333 2016-05-11                  2016-05

以下代码不起作用，任何想法。

    df %>%
      mutate( yrMth = group_by(format(date2, "%Y-%m")))

    df %>%
      rename( yrMth = group_by(format(date2, "%Y-%m")))

Answer 1

df<- group_by(df, date2) %>% mutate(yrMth = format(date2, "%Y-%m"))

这对我来说非常好

但是如果你想在不创建任何新列的情况下这样做，你可以使用以下功能：

df<- mutate_at(df, vars(date), function(x){x =  format(x, "%Y-%m"); return(x)})

Answer 2

无需使用mutate或rename。如eipi10的评论所述，只需执行以下操作即可轻松实现：

df %>% 
  group_by(yrMth = format(date2, "%Y-%m"))

如果要动态命名变量，则可以选择以下方式：

name <- "yrMth2"

df %>% 
  group_by(!!name := get(format(date2, "%Y-%m")) )

Answer 3

我知道这个答案有点晚了，但是在 dplyr_1.0.2 中，您可以在调用 group_by 时简单地设置分组变量名称的名称：

df <- data.frame(Person = c(rep("abc",3), rep("eee", 5)),
             date = c("4/1/2016", "4/3/2016", "4/12/2016", "5/3/2016", "5/4/2016","5/10/2016","5/6/2016", "5/11/2016"),
             account = c("123","123","123","222","222","333","222","333"), stringsAsFactors = F)
df$date2 <- mdy(df$date)
df %>% group_by("yrMth" = format(date2, "%Y-%m"))

使用R中的dplyr重命名group_by语句

3 个答案: