根据规则将数据框中的值替换为其他值

Question

我是R的初学者,并没有找到解决以下问题的方法.任何帮助将非常感激!

我有一个data.frame,并希望用定义的其他值替换列的某些值.

data.frame

date<-c("19921231","19931231","19941231","19941231","19931231","19941231")
variable<-c("a","a","a","b","b","b")
value<-c(1:6)
dataframe <- data.frame(date,variable,value)

试图解决问题

yearend<-c("19921231","19931231","19941231")
year<-c("1992","1993","1994")
map = setNames(yearend,year)
dataframe[] = map[dataframe]

错误信息

Error in map[dataframe] : invalid subscript type 'list'

问题显然是,它不是一个矩阵.解决这个问题最有效的方法是什么？如果我想替换"真实"字符,例如"BGSFDS"和"BASF stock",它也应该有用.

Answer 1

一个很好的功能mapvalues()来自plyr包:

require(plyr)
dataframe$newdate <- mapvalues(dataframe$date, 
          from=c("19921231","19931231","19941231"), 
          to=c("1992","1993","1994"))