如何删除R中数据帧的第一行？ [英] How to delete the first row of a dataframe in R?

问题描述

我有一个11列的数据集，每列超过1000行。列被标记为V1，V2，V11等。
我用c命令替换了对我更有用的东西。
我没有意识到第1行还包含每列的标签，我的实际数据从第2行开始。

有没有办法删除第1行并且递减？

解决方案

保留原始文件中的标签，如下所示：

  df = read.table（'data.txt'，header = T）
  

如果您有列为x和y的列，可以这样解决：

  df $ x 
 df $ y 
  

如果要从数据中实际删除第一行.frame，你可以使用这样的负指数：

  df = df [-1，] 
  

如果要从data.frame中删除列，可以为其分配NULL：

  df $ x = NULL 
  

以下是一些简单的例子，说明如何在R中创建和操作data.frame：

 ＃创建一个data.frame与10 ro ws 
> x = rnorm（10）
> y = runif（10）
> df = data.frame（x，y）
 
＃将其写入文件
> write.table（df，'test.txt'，row.names = F，quote = F）
 
＃从文件中读取一个data.frame：
> read.table（df，'test.txt'，header = T）
 
> df $ x 
 [1] -0.95343778 -0.63098637 -1.30646529 1.38906143 0.51703237 -0.02246754 
 [7] 0.20583548 0.21530721 0.69087460 2.30610998 
> df $ y 
 [1] 0.66658148 0.15355851 0.60098886 0.14284576 0.20408723 0.58271061 
 [7] 0.05170994 0.83627336 0.76713317 0.95052671 
 
> df $ x = x 
> df 
yx 
 1 0.66658148 -0.95343778 
 2 0.15355851 -0.63098637 
 3 0.60098886 -1.30646529 
 4 0.14284576 1.38906143 
 5 0.20408723 0.51703237 
 6 0.58271061  - 0.02246754 
 7 0.05170994 0.20583548 
 8 0.83627336 0.21530721 
 9 0.76713317 0.69087460 
 10 0.95052671 2.30610998 
 
> df [-1，] 
yx 
 2 0.15355851 -0.63098637 
 3 0.60098886 -1.30646529 
 4 0.14284576 1.38906143 
 5 0.20408723 0.51703237 
 6 0.58271061 -0.02246754 
 7 0.05170994 0.20583548 
 8 0.83627336 0.21530721 
 9 0.76713317 0.69087460 
 10 0.95052671 2.30610998 
 
> df $ x = NULL 
> df $ b $ 
 1 0.66658148 
 2 0.15355851 
 3 0.60098886 
 4 0.14284576 
 5 0.20408723 
 6 0.58271061 
 7 0.05170994 
 8 0.83627336 
 9 0.76713317 
 10 0.95052671 
  

I have a dataset with 11 columns with over a 1000 rows each. The columns were labeled V1, V2, V11, etc.. I replaced the names with something more useful to me using the "c" command. I didn't realize that row 1 also contained labels for each column and my actual data starts on row 2.

Is there a way to delete row 1 and decrement?

解决方案

Keep the labels from your original file like this:

df = read.table('data.txt', header = T)

If you have columns named x and y, you can address them like this:

df$x
df$y

If you'd like to actually delete the first row from a data.frame, you can use negative indices like this:

df = df[-1,]

If you'd like to delete a column from a data.frame, you can assign NULL to it:

df$x = NULL

Here are some simple examples of how to create and manipulate a data.frame in R:

# create a data.frame with 10 rows
> x = rnorm(10)
> y = runif(10)
> df = data.frame( x, y )

# write it to a file
> write.table( df, 'test.txt', row.names = F, quote = F )

# read a data.frame from a file: 
> read.table( df, 'test.txt', header = T )

> df$x
 [1] -0.95343778 -0.63098637 -1.30646529  1.38906143  0.51703237 -0.02246754
 [7]  0.20583548  0.21530721  0.69087460  2.30610998
> df$y
 [1] 0.66658148 0.15355851 0.60098886 0.14284576 0.20408723 0.58271061
 [7] 0.05170994 0.83627336 0.76713317 0.95052671

> df$x = x
> df
            y           x
1  0.66658148 -0.95343778
2  0.15355851 -0.63098637
3  0.60098886 -1.30646529
4  0.14284576  1.38906143
5  0.20408723  0.51703237
6  0.58271061 -0.02246754
7  0.05170994  0.20583548
8  0.83627336  0.21530721
9  0.76713317  0.69087460
10 0.95052671  2.30610998

> df[-1,]
            y           x
2  0.15355851 -0.63098637
3  0.60098886 -1.30646529
4  0.14284576  1.38906143
5  0.20408723  0.51703237
6  0.58271061 -0.02246754
7  0.05170994  0.20583548
8  0.83627336  0.21530721
9  0.76713317  0.69087460
10 0.95052671  2.30610998

> df$x = NULL
> df 
            y
1  0.66658148
2  0.15355851
3  0.60098886
4  0.14284576
5  0.20408723
6  0.58271061
7  0.05170994
8  0.83627336
9  0.76713317
10 0.95052671

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