Question

我有这样的df：

$array = @('00155d9df9b8','00155d9df921')
foreach($mac in $array)
{
  Write-Output $mac
}

现在我想创建一列以基于行值向前分配值，就像这样

df.temp = data.frame("t" = c(1,2,3,5,1,3,2,5), "a" = c("a1","a2","a1","a1","a1","a1","a1","a1"), "b" = 
c("b1","b1","b1","b1","b2","b2","b2","b2"))

> df.temp
  t  a  b
1 1 a1 b1
2 2 a2 b1
3 3 a1 b1
4 5 a1 b1
5 1 a1 b2
6 3 a1 b2
7 2 a1 b2
8 5 a1 b2

Answer 1

我们可以将'b'和paste与't'的lead进行分组

library(dplyr)
library(stringr)
df.temp %>% 
      group_by(b) %>% 
      mutate(d = str_c(t, lead(t), sep="_"))
# A tibble: 8 x 4
# Groups:   b [2]
#      t a     b     d    
#  <dbl> <chr> <chr> <chr>
#1     1 a1    b1    1_2  
#2     2 a2    b1    2_3  
#3     3 a1    b1    3_5  
#4     5 a1    b1    <NA> 
#5     1 a1    b2    1_3  
#6     3 a1    b2    3_2  
#7     2 a1    b2    2_5  
#8     5 a1    b2    <NA>

Answer 2

使用ave

的基本R选项

within(df.temp, d <- ave(t,b,FUN = function(x) c(paste(x[-length(x)],x[-1],sep = "_"),NA)))

这样

  t  a  b    d
1 1 a1 b1  1_2
2 2 a2 b1  2_3
3 3 a1 b1  3_5
4 5 a1 b1 <NA>
5 1 a1 b2  1_3
6 3 a1 b2  3_2
7 2 a1 b2  2_5
8 5 a1 b2 <NA>

基于其他列值的行单元格值

2 个答案: