如何使用R中的tidyverse以長格式將列表對象制作為數據幀

Question

dd <- list(c("2020-1-2","SDF","fff,33"),
           c("2020-1-3","KKK","ffd,23","fffdf,23","ssfds,43"))
dd
# [[1]]
# [1] "2020-1-2" "SDF"      "fff,33"  

# [[2]]
# [1] "2020-1-3" "KKK"      "ffd,23"   "fffdf,23" "ssfds,43"

ddtarget <- data.frame(date= c("2020-1-2","2020-1-3","2020-1-3","2020-1-3"),
                       category = c("SDF","KKK","KKK","KKK"),
                       element = c("fff,33","ffd,23","fffdf,23","ssfds,43"))
ddtarget
#       date category  element
# 1 2020-1-2      SDF   fff,33
# 2 2020-1-3      KKK   ffd,23
# 3 2020-1-3      KKK fffdf,23
# 4 2020-1-3      KKK ssfds,43

我想使用諸如map()或類似函數之類的tidyverse將dd轉換為ddtarget，但我自己無法做到。 誰能幫我？

Answer 1

假設前兩列的長度總是為 1，第三列是所有剩余的元素，這里是使用map_df一種方法

purrr::map_df(dd,~tibble(date = .x[1], category = .x[2],element = .x[3:length(.x)]))

# A tibble: 4 x 3
#  date     category element 
#  <chr>    <chr>    <chr>   
#1 2020-1-2 SDF      fff,33  
#2 2020-1-3 KKK      ffd,23  
#3 2020-1-3 KKK      fffdf,23
#4 2020-1-3 KKK      ssfds,43

Answer 2

如果第一個元素始終是date ，第二個元素始終是category ，其余元素始終是element ，則可以執行以下操作：

do.call(rbind, lapply(dd, function(x) {
  data.frame(date = x[1L], category = x[2L], element = tail(x, -2L))
}))
#       date category  element
# 1 2020-1-2      SDF   fff,33
# 2 2020-1-3      KKK   ffd,23
# 3 2020-1-3      KKK fffdf,23
# 4 2020-1-3      KKK ssfds,43

如果length(dd)是大的，你可以考慮使用data.table::rbindlist這比更優化do.call(rbind) data.table::rbindlist(lapply(...))

我還懷疑您的管道早些時候出了點問題dd是從哪里來的？ 為什么采用這種格式？

如果您可以控制創建dd的步驟，您可以考慮更全面地設計您的管道。

Answer 3

另一種選擇是unnest_wider和pivot_longer

library(tibble)
library(dplyr)
library(tidyr)
library(stringr)
tibble(dat = dd) %>%
   unnest_wider(c(dat), names_repair = ~c('date', 'category', str_c('V', 3:length(.)))) %>%
   pivot_longer(cols = V3:V5, values_to = "element", values_drop_na = TRUE) %>%
   select(-name)
# A tibble: 4 x 3
#  date     category element 
#  <chr>    <chr>    <chr>   
#1 2020-1-2 SDF      fff,33  
#2 2020-1-3 KKK      ffd,23  
#3 2020-1-3 KKK      fffdf,23
#4 2020-1-3 KKK      ssfds,43