Question

我有一个数据框pop.subset <-：

state  location   pop
WA     Seattle    100
WA     Kent       20
OR     foo        30
CA     foo2       80

我需要在每个州拥有最低人口的城市存储在data.frame中。我有：

result <- pop.subset %>% 
          group_by(state) %>%
          summarise(min = min(pop))

返回data.frame：

state   min
WA      20
...    .... etc

但我也需要这个城市。我尝试在group_by函数中包含位置，如下所示：group_by(state, location)，但是这会给每个城市的每个城市配对一个州，而不是像城市这样的州：

state location pop
WA    Seattle  100
WA    Kent     20
foo   foo      foo

我错过了一个简单的解决方案吗？我希望我的结果如此：

state location pop
WA    Kent     20
...   ...      ... etc.

Answer 1

你尝试过这样的事吗？

result <- pop.subset %>% 
              group_by(state, location) %>%
              summarise(min = min(both_sexes_2012))

Answer 2

我认为您希望按state分组，然后过滤min(pop)：

pop.subset %>% 
  group_by(state) %>% 
  filter(pop == min(pop)) %>%
  ungroup()

# A tibble: 3 x 3
  state location   pop
  <chr>    <chr> <int>
1    WA     Kent    20
2    OR      foo    30
3    CA     foo2    80

Answer 3

我理解，这解决了它：

library(tibble)

data<-tribble(~state,  ~location,   ~pop,
       "WA",     "Seattle",    100,
       "WA",    "Kent",       20,
       "OR",     "foo" ,       30,
       "CA",     "foo2" ,      80

)

library(dplyr)

data%>%group_by(state)%>%summarise(location=location[which.min(pop)]
                                   ,min=min(pop))


# A tibble: 3 x 3
  state location   min
  <chr>    <chr> <dbl>
1    CA     foo2    80
2    OR      foo    30
3    WA     Kent    20

dplyr使用另一列汇总分组数据

3 个答案: