如何在R中分组和合并列

我有这个数据框：

d

我需要能够把日期放在一个由逗号分隔的单元格中，按产品、日期和月份分组。比如说,

Server1、Serve2、Server4出现在2015-01-062015-01-1412015-01-15105-01-20的1月份

我的新df需要如下所示：

Product                Day  Date    Month  Day_list
Server1,Serve2,Server4 Tues 2015-01-06 Jan 2015-01-06,2015-01-13,2015-01-20 

有没有软件包可以帮助我在R中完成这项工作

我尝试使用data.table包：

d[,d:=paste(Date,Date), c("Product","Day","Month")]

---

不工作

这里有一个使用dplyr的解决方案：

 d %>% mutate(
  Product = gsub("[ ]", "", Product),
  Day = gsub("[ ] ", "", Day )
  ) %>%
  group_by(Product, Month) %>%
  mutate(
    Day_list = paste(Date, collapse = "")
    )

                 Product  Day         Date Month                           Day_list
1 Server1,Serve2,Server4  Tue  2015-01-06    Jan  2015-01-06 2015-01-14 2015-01-15 
2            App_Servers Wed   2015-01-07    Jan                        2015-01-07 
3 Db_servers,application Tue   2015-01-13    Jan                        2015-01-13 
4 Server1,Serve2,Server4 Wed   2015-01-14    Jan  2015-01-06 2015-01-14 2015-01-15 
5 Server1,Serve2,Server4 Thu   2015-01-15    Jan  2015-01-06 2015-01-14 2015-01-15 
6  Server1,Serve2,Sever4 Tue   2015-01-20    Jan                        2015-01-20 
7 Server1,Serve2,Server4 Mon   2015-02-16    Feb             2015-02-16 2015-02-16 
8 Server1,Serve2,Server4 Mon   2015-02-16    Feb             2015-02-16 2015-02-16 

---

这里有几件事

首先，列中有额外的空格。您必须删除，以便将它们组合在一起

require(data.table)
setDT(d)[, `:=`(Product = gsub("[ ]", "", Product),
                Date    = gsub("[ ]", "", Date))]

其次，您错误地使用了

paste（）

和

：=

d[, Date_list := paste(Date, collapse=","), by=c("Product", "Month")]
d
#                   Product  Day       Date Month                        Date_list
# 1: Server1,Serve2,Server4  Tue 2015-01-06   Jan 2015-01-06,2015-01-14,2015-01-15
# 2:            App_Servers Wed  2015-01-07   Jan                       2015-01-07
# 3: Db_servers,application Tue  2015-01-13   Jan                       2015-01-13
# 4: Server1,Serve2,Server4 Wed  2015-01-14   Jan 2015-01-06,2015-01-14,2015-01-15
# 5: Server1,Serve2,Server4 Thu  2015-01-15   Jan 2015-01-06,2015-01-14,2015-01-15
# 6:  Server1,Serve2,Sever4 Tue  2015-01-20   Jan                       2015-01-20
# 7: Server1,Serve2,Server4 Mon  2015-02-16   Feb            2015-02-16,2015-02-16
# 8: Server1,Serve2,Server4 Mon  2015-02-16   Feb            2015-02-16,2015-02-16

看一看这本书的内容和小插曲

---

编辑：我刚刚意识到第6行有一个

产品

的打字错误。如果新的df Day_列表列不是

2015-01-062015-01-1412015-01-1512015-01-20

（基于上述数据），则它是

Sever4

，而不是

Server1、Serve2、Sever4

（不，因为1月份的最后一个条目是

Server1、Serve2、Server4

，而不是

Server1、Serve2、Server4

。但仅仅看一下代码就很难发现：-）。

d[, Date_list := paste(Date, collapse=","), by=c("Product", "Month")]
d
#                   Product  Day       Date Month                        Date_list
# 1: Server1,Serve2,Server4  Tue 2015-01-06   Jan 2015-01-06,2015-01-14,2015-01-15
# 2:            App_Servers Wed  2015-01-07   Jan                       2015-01-07
# 3: Db_servers,application Tue  2015-01-13   Jan                       2015-01-13
# 4: Server1,Serve2,Server4 Wed  2015-01-14   Jan 2015-01-06,2015-01-14,2015-01-15
# 5: Server1,Serve2,Server4 Thu  2015-01-15   Jan 2015-01-06,2015-01-14,2015-01-15
# 6:  Server1,Serve2,Sever4 Tue  2015-01-20   Jan                       2015-01-20
# 7: Server1,Serve2,Server4 Mon  2015-02-16   Feb            2015-02-16,2015-02-16
# 8: Server1,Serve2,Server4 Mon  2015-02-16   Feb            2015-02-16,2015-02-16