按组对多个变量求和,并使用它们的总和创建新列

Question

我有一个带有分组变量的数据框,我想按组对它们求和.这很简单dplyr.

library(dplyr)
library(magrittr)

data <- data.frame(group = c("a", "a", "b", "c", "c"), n1 = 1:5, n2 = 2:6)

data %>% group_by(group) %>%
  summarise_all(sum)

# A tibble: 3 x 3
   group    n1    n2
  <fctr> <int> <int>
1      a     3     5
2      b     3     4
3      c     9    11

但现在我想要一个新的列total,其中包含n1和n2按组的总和.像这样:

# A tibble: 3 x 3
   group    n1    n2   ttl
  <fctr> <int> <int> <int>
1      a     3     5     8
2      b     3     4     7
3      c     9    11    20

我怎么能这样做dplyr？

编辑: 实际上,这只是一个例子,我有很多变数.

我尝试了这两个代码,但它不是正确的维度......

data %>% group_by(group) %>%
  summarise_all(sum) %>%
  summarise_if(is.numeric, sum)

data %>% group_by(group) %>%
  summarise_all(sum) %>%
  mutate_if(is.numeric, .funs = sum)

Answer 1

您可以使用mutate后summarize:

data %>% 
    group_by(group) %>%
    summarise_all(sum) %>% 
    mutate(tt1 = n1 + n2)

# A tibble: 3 x 4
#   group    n1    n2   tt1
#  <fctr> <int> <int> <int>
#1      a     3     5     8
#2      b     3     4     7
#3      c     9    11    20

如果需要对所有数字列求和,可以使用rowSumswith select_if(选择数字列)对列进行求和:

data %>% 
    group_by(group) %>%
    summarise_all(sum) %>% 
    mutate(tt1 = rowSums(select_if(., is.numeric)))

# A tibble: 3 x 4
#   group    n1    n2   tt1
#  <fctr> <int> <int> <dbl>
#1      a     3     5     8
#2      b     3     4     7
#3      c     9    11    20