将向量转换为类似矩阵的对象

Question

我在将向量转换为类似矩阵的对象时遇到了问题。乍一看，这题一定很简单，但我还没解决。

问题描述：

我有一些长向量，类似于下面提到的那个：

m <- c("100€", "25m²", "2 rooms", "12m²", "4 rooms", "500€", "3 rooms")

我想把它转成下面结构的data.frame（或矩阵）：

  price surface    rooms
   100€    25m²  2 rooms 
     NA    12m²  4 rooms
   500€     NA   3 rooms

Answer 1

你可以这样尝试，分别计算列索引和行索引，然后使用索引将向量分配给矩阵：

col <- ifelse(grepl("€", m), 1, ifelse(grepl("m²", m), 2, 3))

col
# [1] 1 2 3 2 3 1 3

row <- cumsum(c(T, diff(col) < 0))     # calculate the row index based on the column index, 
                                       # when you encounter a decrease of the column index, 
                                       # increase the row index by one
row
# [1] 1 1 1 2 2 3 3

mat <- matrix(nrow = max(row), ncol = max(col))
mat[cbind(row, col)] <- m

mat
#     [,1]   [,2]   [,3]     
#[1,] "100€" "25m²" "2 rooms"
#[2,] NA     "12m²" "4 rooms"
#[3,] "500€" NA     "3 rooms"

将向量转换为类似矩阵的对象

Transforming vector into matrix-like object

r

vector

reshape