将数据帧的两列转换为命名向量

Question

我需要将多行两列data.frame转换为命名字符向量。 我data.frame会是这样的：

dd = data.frame(crit = c("a","b","c","d"), 
       name = c("Alpha", "Beta", "Caesar", "Doris") 
       ) 

，我真正需要是什么：

whatiwant = c("a" = "Alpha", 
       "b" = "Beta", 
       "c" = "Caesar", 
       "d" = "Doris") 

Answer 1

使用names功能：

whatyouwant <- as.character(dd$name) 
names(whatyouwant) <- dd$crit 

as.character是必要的，因为data.frame和read.table用默认设置将字符转换为因子。

如果你想要一个班轮：

whatyouwant <- setNames(as.character(dd$name), dd$crit) 

Answer 2

您可以从dd$name做载体，并使用names()加名字，但你可以用structure()做到这一切在一个步：

whatiwant <- structure(as.character(dd$name), names = as.character(dd$crit)) 

Answer 3

对于品种，试着split和unlist：

unlist(split(as.character(dd$name), dd$crit)) 
#  a  b  c  d 
# "Alpha" "Beta" "Caesar" "Doris"