减去特定行并重命名它

Question

是否可以减去某些行并重命名它们？

year <- c(2005,2005,2005,2006,2006,2006,2007,2007,2007)
category <- c("a","b","c","a","b","c", "a", "b", "c")
value <- c(2,2,10,3,3,12,4,4,16)
df <- data.frame(year, category,value, stringsAsFactors = FALSE)

结果应该是这样的：

year	category	value
2005	a	2
2005	b	2
2005	c	4
2006	a	3
2006	b	3
2006	c	12
2007	a	4
2007	b	4
2007	c	16
2005	c-b	2
2006	c-b	9
2007	c-b	12

Answer 1

您可以使用 group_modify:

library(tidyverse)
df %>% 
  group_by(year) %>% 
  group_modify(~ add_row(.x, category = "c-b", value = .x$value[.x$category == "c"] - .x$value[.x$category == "b"]))

# A tibble: 12 x 3
# Groups:   year [3]
    year category value
   <dbl> <chr>    <dbl>
 1  2005 a            2
 2  2005 b            2
 3  2005 c           10
 4  2005 c-b          8
 5  2006 a            3
 6  2006 b            3
 7  2006 c           12
 8  2006 c-b          9
 9  2007 a            4
10  2007 b            4
11  2007 c           16
12  2007 c-b         12

Answer 2

参见substract()函数。

示例：

substracted_df<-substr(df,df$category=="c")

如果您想知道您正在处理哪些行，请使用 which()

rows<-which(df$category=="c")
substracted_df<-df[rows, ]

您可以将每个需要的行重命名为

row.names(substracted_df)<-c("Your desired row names")

减去特定行并重命名它

subtract specific row und rename it

row

r

subset

subtraction

dataframe