将数据帧转换为矩阵，其中第1列的df为矩阵的rownames [英] convert data frame to a matrix with column 1 of df as rownames of matrix

问题描述

我有一个尺寸为3695 X 20的数据框。第一列包含字母数字标识符，其他19列都是数字。所以，rownames（df）提供数字1-3695，而colnames（df）给出列的名称。 df [，1]提供字母数字标识符。

我想将数据帧转换为矩阵，并使用现有数据帧的第1列作为新矩阵，并将数据框的列名称保持为矩阵的列名。

我也想自动化此过程以用于类似数据帧但不同的维度。那么，如果这个解决方案需要知道行数和/或列的数量，那么如何在不必查看显示器的情况下将这些信息传入代码呢？

我看过data.matrix和reshape2，但似乎无法弄清楚如何做我想要的。

解决方案

使用您的样本数据

  X< c（AT1G01040，AT1G01270，AT1G01471，AT1G01680），log2.fold_change._Mer7_2.1_Mer7_2.2 = c（0,0,0,0），log2.fold_change._Mer7_1.2_W29_S226A_1 = c 0，0，-1.14，0），log2.fold_change._Mer7_1.2_W29_1 = c（0,0,0,0）），.Names = c（gene，log2.fold_change._Mer7_2.1_Mer7_2.2 ，log2.fold_change._Mer7_1.2_W29_S226A_1，log2.fold_change._Mer7_1.2_W29_1），row.names = c（NA，4L），class =data.frame）
  

您可以编写一个简单的帮助函数来创建一个矩阵并设置正确的名称

  matrix.please< -function（x）{
 m< -as.matrix（x [， -  1]）$ ​​b $ b rownames（m） [，1] 
m 
} 
  

你会使用它像

  M<  -  ma trix.please（X）
 str（M）
＃num [1：4，1：3] 0 0 0 0 0 0 -1.14 0 0 0 ... 
＃ -  attr （*，dimnames）= 2 
＃..的列表$：chr [1：4]AT1G01040AT1G01270AT1G01471AT1G01680
＃.. $：chr [1 ：3]log2.fold_change._Mer7_2.1_Mer7_2.2
＃log2.fold_change._Mer7_1.2_W29_S226A_1log2.fold_change._Mer7_1.2_W29_1
  

所以我们有一个4x3矩阵，具有正确的行和列名。

I have a data frame with dimensions 3695 X 20. The first column contains alphanumeric identifiers, the other 19 columns are all numeric. So, rownames(df) provides the numbers 1-3695, and colnames(df) gives the names of the columns. df[,1] provides the alphanumeric identifiers.

I would like to convert the data frame to a matrix and use column 1 of the existing data frame to be the rownames of the new matrix and maintain the column names of the data frame as the column names of the matrix.

I would also like to automate this process for use with data frames of similar but different dimensions. So, if the solution to this requires knowing the number of rows and/or columns, how can I get this information into the code without me having to look at the monitor ?

I have looked at data.matrix and reshape2 but can not seem to figure out how to do what I want.

解决方案

With your sample data

X<-structure(list(gene = c("AT1G01040", "AT1G01270", "AT1G01471", "AT1G01680"), log2.fold_change._Mer7_2.1_Mer7_2.2 = c(0, 0, 0, 0), log2.fold_change._Mer7_1.2_W29_S226A_1 = c(0, 0, -1.14, 0 ), log2.fold_change._Mer7_1.2_W29_1 = c(0, 0, 0, 0)), .Names = c("gene", "log2.fold_change._Mer7_2.1_Mer7_2.2", "log2.fold_change._Mer7_1.2_W29_S226A_1", "log2.fold_change._Mer7_1.2_W29_1"), row.names = c(NA, 4L), class = "data.frame")

You can write a simple helper function to create a matrix and set the right names

matrix.please<-function(x) {
    m<-as.matrix(x[,-1])
    rownames(m)<-x[,1]
    m
}

and you would use it like

M <- matrix.please(X)
str(M)
#  num [1:4, 1:3] 0 0 0 0 0 0 -1.14 0 0 0 ...
#  - attr(*, "dimnames")=List of 2
#   ..$ : chr [1:4] "AT1G01040" "AT1G01270" "AT1G01471" "AT1G01680"
#   ..$ : chr [1:3] "log2.fold_change._Mer7_2.1_Mer7_2.2"  
# "log2.fold_change._Mer7_1.2_W29_S226A_1" "log2.fold_change._Mer7_1.2_W29_1"

So we have a 4x3 matrix with the correct row and col names.

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