根據兩個標準為每組獲取多個值

我正在嘗試對資料集進行分組，并根據時間和速度的兩個獨立度量獲得第一個和最高值。所以我需要每個組中最早記錄的時間和速度，然后是每個組中最快記錄的時間和速度。我已經走了這么遠，但需要一些幫助......

library(tidyverse)
group <- c(1,1,1,1,1,2,2,3,3,4,4,4,4,4,4)
time <- c(1,6,4,5,7,12,10,2,3,8,9,11,13,14,15)
speed <- c(17,6, 99, 34, 12, 5, 67, 43, 23, 12, 15, 78, 61, 78, 20)
data = data.frame(group, time, speed)
summary = data %>% 
  group_by(group) %>%
  summarise(
    firstTime =  # lowest time
    HighestSpeedTime = , # time for highest speed
    firstSpeed = , #speed for lowest time
    highestSpeed = max(speed), # highest speed
  )

uj5u.com熱心網友回復：

這行得通嗎？

library(tidyverse)
group <- c(1,1,1,1,1,2,2,3,3,4,4,4,4,4,4)
time <- c(1,6,4,5,7,12,10,2,3,8,9,11,13,14,15)
speed <- c(17,6, 99, 34, 12, 5, 67, 43, 23, 12, 15, 78, 61, 78, 20)
data = data.frame(group, time, speed)

summary <-  data |> 
  arrange(group, time) |> 
  group_by(group) |> 
  summarise(
    firsttime = min(time),
    highest_speed = max(speed)
  ) |> 
  left_join(data, by = c("group", "highest_speed" = "speed")) |> 
  group_by(group) |> 
  slice(1) |> 
  rename(highest_speed_time = time) |> 
  left_join(data, by = c("group", "firsttime" = "time")) |> 
  rename(first_speed = speed)

summary

  # group firsttime highest_speed highest_speed_time first_speed
  # <dbl>     <dbl>         <dbl>              <dbl>       <dbl>
  #     1         1            99                  4          17
  #     2        10            67                 10          67
  #     3         2            43                  2          43
  #     4         8            78                 11          12

uj5u.com熱心網友回復：

另一個解決方案，帶有鏈接inner_join：

library(tidyverse)

data %>% 
  group_by(group) %>% 
  summarise(firstTime = min(time)) %>% 
  inner_join(data,by=c("group", "firstTime"="time")) %>% 
  rename(firstSpeed=speed) %>% 
  inner_join(
    data %>% 
      group_by(group) %>% 
      summarise(highestSpeed = max(speed)) %>% 
      inner_join(data,by=c("group", "highestSpeed"="speed")) 
  ) %>% 
  relocate(highestTime=time, .before="highestSpeed")

#> Joining, by = "group"
#> # A tibble: 5 × 5
#>   group firstTime firstSpeed highestTime highestSpeed
#>   <dbl>     <dbl>      <dbl>       <dbl>        <dbl>
#> 1     1         1         17           4           99
#> 2     2        10         67          10           67
#> 3     3         2         43           2           43
#> 4     4         8         12          11           78
#> 5     4         8         12          14           78

uj5u.com熱心網友回復：

這是一個 data.table 方法

library(data.table)
setDT(data)
temp <- data[data[, .I[speed == max(speed)], by = .(group)]$V1]
setnames(temp, new = c("group", "maxSpeedTime", "maxSpeed"))
# join together
data[, .(firstTime  = time[1],
         firstSpeed = speed[1]), 
     by = .(group)][temp, on = .(group)]
#    group firstTime firstSpeed maxSpeedTime maxSpeed
# 1:     1         1         17            4       99
# 2:     2        12          5           10       67
# 3:     3         2         43            2       43
# 4:     4         8         12           11       78
# 5:     4         8         12           14       78

uj5u.com熱心網友回復：

更新： 這應該有效：在第 4 組中，我們有 2 行：（我們在兩個時間點有最高速度）！

library(dplyr)
data %>% 
  group_by(group) %>%
  summarise(
    firstTime = min(time), # lowest time
    HighestSpeedTime = time[which(speed==max(speed))], # time for highest speed
    firstSpeed = speed[which(time==min(time))],#speed for lowest time
    highestSpeed = max(speed) # highest speed
  ) 

輸出：

  group firstTime HighestSpeedTime firstSpeed highestSpeed
  <dbl>     <dbl>            <dbl>      <dbl>        <dbl>
1     1         1                4         17           99
2     2        10               10         67           67
3     3         2                2         43           43
4     4         8               11         12           78
5     4         8               14         12           78

標籤：r dplyr

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