从列的值

Question

数据框包含以下格式的信息：

Type        Value
-------------------
catA        one
catB        two
catA        three

我的目标是将数据帧转换为此格式（将类型的值转换为列）：

catA        catB
-----------------
 one          -
  -          two
three         -

我一直在研究“虚拟变量”，但这不是我需要的。 ¿有人能给我一些想法吗？

Answer 1

 library(reshape2)
 df <- data.frame(Type=c("catA","catB","catA"),value=c("one","two","three"))
 df
 #   Type value
 # 1 catA   one
 # 2 catB   two
 # 3 catA three

 dcast(df,value~Type)
 #   value  catA catB
 # 1   one   one <NA>
 # 2 three three <NA>
 # 3   two  <NA>  two

 dcast(df,Type~value)
 #   Type  one three  two
 # 1 catA  one three <NA>
 # 2 catB <NA>  <NA>  two

保留value

的顺序

 df$Type <- factor(df$Type,c("catA","catB"))
 df$value <- factor(df$value,c("one","two","three"))

 dcast(df,Type~value)
 #   Type  one  two three
 # 1 catA  one <NA> three
 # 2 catB <NA>  two  <NA>

 dcast(df,value~Type)
 #   value  catA catB
 # 1   one   one <NA>
 # 2   two  <NA>  two
 # 3 three three <NA>

Answer 2

你有一个长格式表，你想要一个宽格式。使用dcast()包中的reshape2函数。

Answer 3

由于您没有使用矩形数据集，因此将结果存储在列表中可能更有意义。这可以通过unstack：

来完成

unstack(df, form=Value~Type)
$catA
[1] "one"   "three"

$catB
[1] "two"

数据

df <- read.table(header=T, text="Type        Value
catA        one
catB        two
catA        three")