R-根据列的值将数据帧重新组织为多列

我需要重新组织我的dataframe intro多列（基于列“x”和“y”（忽略列“z”）的值）：

---

像这样的东西

> library(reshape2)
> dcast(dataframe, y~x, value.var = "y")
  y apple banana orange strawberry
1 a     a   <NA>   <NA>       <NA>
2 b     b   <NA>   <NA>       <NA>
3 c  <NA>   <NA>      c       <NA>
4 d     d   <NA>   <NA>       <NA>
5 e  <NA>   <NA>      e       <NA>
6 f  <NA>   <NA>      f       <NA>
7 g  <NA>      g   <NA>       <NA>
8 h  <NA>      h   <NA>       <NA>
9 i  <NA>   <NA>   <NA>          i

>库（2）
>dcast（数据帧，y~x，value.var=“y”）
苹果香蕉橙草莓
a
2b
3C
四维
5 e e
6f
7克
8小时
9 i i

您还可以创建一个简单的函数

max_val = 3 # Max number of rows your final dataframe will have
mdf = as.data.frame(matrix(nrow = max_val))[-1] # Create empty df

for (item in unique(df$x)) {
    vals = df[df$x == item, ]$y
    while (length(vals) != max_val){
        vals = c(array(vals), NA)
    }
    n = names(mdf)
    mdf = cbind(mdf, vals)
    names(mdf) <- c(n, item)
}

> library(reshape2)
> dcast(dataframe, y~x, value.var = "y")
  y apple banana orange strawberry
1 a     a   <NA>   <NA>       <NA>
2 b     b   <NA>   <NA>       <NA>
3 c  <NA>   <NA>      c       <NA>
4 d     d   <NA>   <NA>       <NA>
5 e  <NA>   <NA>      e       <NA>
6 f  <NA>   <NA>      f       <NA>
7 g  <NA>      g   <NA>       <NA>
8 h  <NA>      h   <NA>       <NA>
9 i  <NA>   <NA>   <NA>          i

max_val = 3 # Max number of rows your final dataframe will have
mdf = as.data.frame(matrix(nrow = max_val))[-1] # Create empty df

for (item in unique(df$x)) {
    vals = df[df$x == item, ]$y
    while (length(vals) != max_val){
        vals = c(array(vals), NA)
    }
    n = names(mdf)
    mdf = cbind(mdf, vals)
    names(mdf) <- c(n, item)
}

  apple orange banana strawberry
1     a      c      7          9
2     d      e      8         NA
3     b      f     NA         NA