R 删除字符向量中的重复元素，而不是重复的行

Question

我遇到了这个问题。

我有一个数据框(日期)，其中一些文档 ID 和日期存储在字符向量中:

  Doc     Dates
1 12345 c("06/01/2000","08/09/2002")
2 23456 c("07/01/2000", 09/08/2003", "07/01/2000")
3 34567 c("09/06/2004", "09/06/2004", "12/30/2006")
4 45678 c("06/01/2000","08/09/2002")

我正在尝试删除日期中的重复元素以获得此结果:

  Doc     Dates
1 12345 c("06/01/2000","08/09/2002")
2 23456 c("07/01/2000", 09/08/2003")
3 34567 c("09/06/2004", "12/30/2006")
4 45678 c("06/01/2000","08/09/2002")

我试过了:

R>unique(dates$dates)

但它按日期删除重复的行:

  Doc     Dates
1 12345 c("06/01/2000","08/09/2002")
2 23456 c("07/01/2000", 09/08/2003")
3 34567 c("09/06/2004", "12/30/2006")

关于如何仅删除日期中的重复元素而不是按日期删除重复的行的任何帮助？

** 更新数据

# Match some text string (dates) from some text:

df1$dates <- as.character(strapply(df1[[2]], "((\\D\\d{1,2}(/|-)\\d{1,2}(/|-)\\d{2,4})|    ([^/]\\d{1,2}(/|-)\\d{2,4})|((JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV){1}[\\s|-]{0,2}\\d{1,4}(\\D[\\s|-]{0,}\\d{2,4}){0,}))"))

# Drop first 2 columns from dataframe
df2<-df1[ -c(1,2)]

# List data
>df2
872                     7/23/2007
873 c(" 11/4/2007", " 11/4/2007")
874   c(" 4/2/2008", " 8/2/2007")
880                    11/14/2006

> class(df2)
[1] "data.frame"

> class(df2$dates)
[1] "character"

> dput(df2)
structure(list(dates = c("NULL", "NULL", " 7/23/2007", "c(\" 11/4/2007\", \" 11/4/2007\")", 
"c(\" 4/2/2008\", \" 8/2/2007\")", "NULL", "NULL", "NULL", "NULL", 
"NULL", " 11/14/2006")), .Names = "dates", class = "data.frame", row.names = 870:880)

所以我的问题是如何摆脱第 873 行中的重复日期？

Answer 1

尝试这个:

within(dates, Dates <- lapply(Dates, unique))