将矩阵转换为数字数据框 [英] convert matrix to numeric data frame

问题描述

我有一些不方便使用的数据格式.它保存为矩阵，所有列向量均为字符.

I have some data in a somewhat inconvenient format. It is saved as a matrix, with all column vectors being characters.

datamatrix <- structure(c("1", "2", "3", "4", "0.9301", "0.93", "0.9286", "0.9209", 
                          "0.9", "0.8064", "0.7947", "0.7607", "0.8042", "0.7847", "0.7832", 
                          "0.7578", "0.7487", "0.7105", "0.6566", "0.5951", "0.6951", "0.677", 
                          "0.6588", "0.5922", "0.6889", "0.6471", "0.6524", "0.5932"), .Dim = c(4L, 
                                                                                                7L))

我的目标是将该矩阵转换为数据框，并将列向量转换为类数字.

My aim is to convert this matrix to a dataframe and the column vectors to the class numeric.

我尝试了以下过程:

1)

datamatrix2 <- as.data.frame(datamatrix)
datamatrix2 <- as.numeric(datamatrix2)

这给出了错误:

"Error: (list) object cannot be coerced to type 'double'"

2)所以我尝试了sapply:

2) So I try it with sapply:

datamatrix3 <- as.data.frame(sapply(datamatrix, as.numeric))

这会将我之前拥有的所有列都放在长列中.

This puts all the columns I had before in only long column.

3)当我对转换为数据帧(但仍然是字符向量)的数据使用2)中的apply函数时，它将取自第一列(1,2,3,4)的值并将其放入其他所有列(但按降序排列).

3) When I use the apply function from 2) on the data already transformed into a dataframe (but still character vectors), it takes the values from the first column (1,2,3,4) and puts it in all other columns (but in a descending order).

datamatrix4 <- as.data.frame(sapply(datamatrix2, as.numeric))

推荐答案

转换矩阵的最佳方法是更改​​mode.这样，您可以制作矩阵numeric，然后可以轻松地将其转换为数据帧:

Nicest way to convert matrices is to change the mode. This way you can make the matrix numeric, then you can convert to data frame easily:

mode(datamatrix) = "numeric"
data.frame(datamatrix)
#   X1     X2     X3     X4     X5     X6     X7
# 1  1 0.9301 0.9000 0.8042 0.7487 0.6951 0.6889
# 2  2 0.9300 0.8064 0.7847 0.7105 0.6770 0.6471
# 3  3 0.9286 0.7947 0.7832 0.6566 0.6588 0.6524
# 4  4 0.9209 0.7607 0.7578 0.5951 0.5922 0.5932

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