r-在data.frame(长格式)中计算总和

Question

我想计算2005年、2006年、2007年和a、b、c类数据帧的总和。

year <- c(2005,2005,2005,2006,2006,2006,2007,2007,2007)
category <- c("a","a","a","b","b","b","c","c","c")
value <- c(3,6,8,9,7,4,5,8,9)
df <- data.frame(year, category,value, stringsAsFactors = FALSE)

表格应该是这样的：

>td style="text-align:right；">6>td style="text-align:right；">9

year	category	value
2005	a	1
2005	a	1
2005	a	1
2006	b	2
2006	b	2
2006	b	2
2007	c	3
2007	c	3
2007	c	3
2006	a	3
2007	b
2008	c

使用dplyr包：

df %>% 
group_by(year, category) %>% 
summarise(sum = sum(value))
# # A tibble: 3 × 3
# # Groups:   year [3]
#    year category   sum
#   <dbl> <chr>    <dbl>
# 1  2005 a           17
# 2  2006 b           20
# 3  2007 c           22

如果您希望添加一列作为总和而不是折叠它，请将summarise()替换为mutate()

df %>% 
group_by(year, category) %>% 
mutate(sum = sum(value))
# # A tibble: 9 × 4
# # Groups:   year, category [3]
#    year category value   sum
#   <dbl> <chr>    <dbl> <dbl>
# 1  2005 a            3    17
# 2  2005 a            6    17
# 3  2005 a            8    17
# 4  2006 b            9    20
# 5  2006 b            7    20
# 6  2006 b            4    20
# 7  2007 c            5    22
# 8  2007 c            8    22
# 9  2007 c            9    22

使用aggregate的基本R解决方案

rbind( df, aggregate( value ~ year + category, df, sum ) )
year category value
1  2005        a     3
2  2005        a     6
3  2005        a     8
4  2006        b     9
5  2006        b     7
6  2006        b     4
7  2007        c     5
8  2007        c     8
9  2007        c     9
10 2005        a    17
11 2006        b    20
12 2007        c    22