从下一行的值向dataframe添加一列

I have a dataframe with the below structure and values:

我有一个dataframe，它的结构和值如下:

total_size <- 5000;
id line_number
1   1232
2   1456
3   1832
4   2002

I need to add a new column dynamically to the data frame with values from the next_row. ie: The new column value should be: (line_number) of next row -1. The value of the last row should be populated with the total_size value.

我需要用next_row的值动态地向数据框架添加一个新的列。ie:新的列值应该是:(line_number)下一行-1。最后一行的值应该用total_size值填充。

The final output I need to produce is:

我需要生产的最终输出是:

id line_number   end_line_number
1   1232         1455
2   1456         1831
3   1832         2001
4   2002         5000

Any idea how I can generate this dynamically in R?

知道如何在R中动态生成这个吗?

1 个解决方案

#1

This is pretty basic question. You can create a new column by removing the first entry of the 2nd column, subtracting 1 from it and adding NA for the last entry.

这是一个非常基本的问题。您可以通过删除第二列的第一个条目、从中减去1并为最后一个条目添加NA来创建一个新列。

# assuming your data.frame is called 'dt'
dt$end_line_number <- c(dt$line_number[-1]-1, NA)

(or) using transform

(或)使用变换

dt <- transform(dt, end_line_number = c(line_number[-1]-1, NA))

#1