重新聚合数据帧

Question

如果我们的婚姻数据框看起来像这样

   Month  Year marriage_counts
1    Jan  2011              50
2    Jan  2011              30
3    Jan  2011              20
4    Feb  2011              80
5    Feb  2011              10

我们的业务数据如下所示

  Month Year
1   Jan 2011
2   Jan 2011
3   Jan 2011
4   Feb 2011
5   Feb 2011

这应该返回一个看起来像

 Month Year marriage_count
1  Jan 2011            100
2  Feb 2011             90

但我被困在这里..有人可以帮助我吗？

Answer 1

在基数R中：

agg <- aggregate(marriage_counts ~ Month + Year, marriage, sum)

通过Dplyr：

library(dplyr)
df_marriage %>% group_by(Month, Year) %>% 
  summarise(marriage_count = sum(marriage_counts))

通过Data.table：

data.table::setDT(marriage)[, .(marriage_count = sum(marriage_counts)) , by = .(Month, Year)]

Answer 2

使用{purrr}另一种选择。 slice_rows()等同于dplyr的group_by() 。

library(purrr)
df_marriage <- data.frame(Month           = c("Jan", "Jan", "Jan", "May", "May"), 
                          Year            = 2011,
                          marriage_counts = c(50, 30, 20, 80, 10))

df_marriage %>% slice_rows(c("Month", "Year")) %>% by_slice(map, sum)