基于Integer的连接列字符串

例如，我想创建如下所示的字符串，如第一次选举所示。基于Integer的连接列字符串

DF：

Name   Party  FirstElected 
Bob   Liberal  1985 
Joe   Republican 1985 
Sarah  Green  1980 
Bill  Libertarian 1980 
Tom  Conservative 1987

目标：

Year   PeopleElected 
1985 "Bob (Liberal); Joe (Republican)" 
1980 "Sarah (Green); Bill (Libertarian)" 
1987 "Tom (Conservative)"

我承担的paste和apply/aggregate一些组合可以做到这一点......但我还没有多少运气至今。

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2015-09-21 lnNoam

认为大可不必为正则表达式。 –

我们可以使用paste/sprintf创建按'FirstElected'分组的格式。我们将'data.frame'转换为'data.table'（setDT(df1)），按'FirstElected'分组，我们用括号将'Party'包装起来，使用sprintf连接'Name'，然后用paste与collapse='; '创建单个字符串。

library(data.table) 
setDT(df1)[,list(PeopleElected=paste(sprintf('%s (%s)', 
       Name, Party), collapse="; ")) , by = FirstElected] 
# FirstElected      PeopleElected 
#1:   1985 Bob (Liberal); Joe (Republican) 
#2:   1980 Sarah (Green); Bill (Libertarian) 
#3:   1987    Tom (Conservative)

或使用单一paste

setDT(df1)[, list(PeopleElected=paste(Name, ' (', Party, ')', 
      sep='', collapse='; ')) , by=FirstElected]

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2015-09-21 10:18:03 akrun

一如既往的有益和教育，akrun。非常感谢。 – lnNoam

而一个dplyr方法（因为我不说话data.table还）

df1 <- data.frame(Name = c("Bob", "Joe", "Sarah", "Bill", "Tom"), 
        Party = c("Liberal", "Republican", "Green", "Libertarian", 
          "Conservative"), 
        FirstElected = c(1985, 1985, 1980, 1980, 1987)) 

df1 %>% 
    group_by(FirstElected) %>% 
    summarise(PeopleElected = paste0(paste0(Name, " (", Party, ")"), 
            collapse = "; ")) 

Source: local data frame [3 x 2] 

    FirstElected      PeopleElected 
     (dbl)        (chr) 
1   1980 Sarah (Green); Bill (Libertarian) 
2   1985 Bob (Liberal); Joe (Republican) 
3   1987    Tom (Conservative)

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2015-09-21 10:31:11 Benjamin

基于Integer的连接列字符串

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