将带有列表列的数据框保存为 csv 文件

Question

我有以下看起来像这样的数据框（3 列作为列表）。

A tibble: 14 x 4
                                                    clinic_name drop_in_hours appointment_hours   services
                                                          <chr>        <list>            <list>     <list>
     1                   Birth Control and Sexual Health Centre    <list [1]>        <list [1]> <list [1]>
     2 Black Creek Community Health Centre (Sheridan Mall Site)    <list [1]>        <list [1]> <list [1]>
     3 Black Creek Community Health Centre (Yorkgate mall Site)    <list [1]>        <list [1]> <list [1]>
     4                                         Crossways Clinic    <list [1]>        <list [1]> <list [1]>
     5                                       Hassle Free Clinic    <list [1]>        <list [1]> <list [1]>
     6                          Immigrant Women's Health Center    <list [1]>        <list [1]> <list [1]>
     7                          Rexdale Community Health Center    <list [1]>        <list [1]> <list [1]>
     8                            Rexdale Youth Resource Center    <list [1]>        <list [1]> <list [1]>
     9                         Scarborough Sexual Health Clinic    <list [1]>        <list [1]> <list [1]>
    10                                 Special Treatment Clinic    <list [1]>        <list [1]> <list [1]>
    11                            Taibu Community Health Center    <list [1]>        <list [1]> <list [1]>
    12                                                 The Gate    <list [1]>        <list [1]> <list [1]>
    13                                   The Jane Street Clinic    <list [1]>        <list [1]> <list [1]>
    14                                            The Talk Shop    <list [1]>        <list [1]> <list [1]>

我想将其输出为 csv 文件。我注意到数据框的列不应该是 R 中的列表。所以我做了一些谷歌并找到了这个 save data.frames with list-column 所以我试了一下：

library(tidyverse)

df %>% 
  mutate(drop_in_hours = map_chr(drop_in_hours, ~ capture.output(dput(.))),
         appointment_hours = map_chr(appointment_hours, ~ capture.output(dput(.))),
         services = map_chr(services, ~ capture.output(dput(.)))     ) %>% 
  write_csv("health.csv")

但是我遇到了一个错误，我在这里遗漏了什么吗？

Error in mutate_impl(.data, dots) : 
  Evaluation error: Result 4 is not a length 1 atomic vector

.

Answer 1

创建一个包含列表列的小标题：

library(tibble)

clinic_name <- c('bobo center', 'yoyo plaza', 'lolo market')
drop_in_hours <- list(c("Monday: 2 pm - 5 pm", "Tuesday: 4 pm - 7 pm")) 
appointment_hours <- list(c("Monday: 1 pm - 2 pm", "Tuesday: 2 pm - 3 pm")) 
services <- list(c("skin graft", "chicken heart replacement"))

tibb <- data_frame(clinic_name, drop_in_hours, appointment_hours, services)

print(tibb)

编写一个通用函数，将任何列表列转换为字符类型：

set_lists_to_chars <- function(x) {
    if(class(x) == 'list') {
    y <- paste(unlist(x[1]), sep='', collapse=', ')
    } else {
    y <- x 
    }
    return(y)
}

将函数应用于带有列表列的小标题：

new_frame <- data.frame(lapply(tibb, set_lists_to_chars), stringsAsFactors = F)

new_frame

将新格式化的数据框写入 csv 文件：

write.csv(new_frame, file='Desktop/clinics.csv')

这是一个 csv 文件，列表列扩展为常规字符串。

这是一个包罗万象的功能。只需传入你的 tibble 和文件名：

tibble_with_lists_to_csv <- function(tibble_object, file_path_name) {
    set_lists_to_chars <- function(x) { 
        if(class(x) == 'list') { y <- paste(unlist(x[1]), sep='', collapse=', ') } else { y <- x  } 
        return(y) }
    new_frame <- data.frame(lapply(tibble_object, set_lists_to_chars), stringsAsFactors = F)
    write.csv(new_frame, file=file_path_name)
}

用法：

tibble_with_lists_to_csv(tibb, '~/Desktop/tibb.csv')

Answer 2

这是另一个可能更简单的选项。

根据数据，逗号分隔的值可能会变得复杂，因此我使用条形 | 来分隔列表列中的值：

library(tidyverse)

starwars %>% 
  rowwise() %>% 
  mutate_if(is.list, ~paste(unlist(.), collapse = '|')) %>% 
  write.csv('df_starwars.csv', row.names = FALSE)

starwars 是 dplyr 示例数据帧之一。

Answer 3

我有一个类似的数据框，其中包含我想保存为 csv 的列表列。我想出了这个方法。以及如何将列转回列表。

library(tidyverse)

# create a df with a list column
df <- tibble(x=rep(1:5,each=2), y=LETTERS[1:10]) %>%
  group_by(x) %>%
  summarise(z=list(y))

# this throws an error
write_csv(df, "test.csv")

# convert the list column to a string
df2 <- df %>%
  group_by(x) %>% # where x==unique(x)
  mutate(z=paste(z))

# this works
write_csv(df2, "test.csv")

# read the csv
df3 <- read_csv("test.csv")

# reconstruct original df by parsing the strings
# https://stackoverflow.com/questions/1743698/evaluate-expression-given-as-a-string
df4 <- df3 %>%
  group_by(x) %>% 
  mutate(z=list(eval(parse(text=z))))

Answer 4

您是否有任何特定原因要将列保存为列表？或者，您可以使用 unnest 并将其保存在 csv 中。下面的例子

library(tidyverse)
df_list<-data_frame(abc = letters[1:3], lst = list(1:3, 1:3, 1:3))
df_list %>% unnest() %>% write.csv("list.csv")

此外，当您阅读文件时，您可以nest 回复

df <- read.csv("list.csv")[ ,2:3]
df %>% nest(lst)

Answer 5

exploratory::list_to_text() 会将list 列转换为character 列。默认值为sep = ", "，如果写入.csv，我建议将其更改为其他内容。

devtools::install_github("exploratory-io/exploratory_func")

list_to_text <- function(column, sep = ", "){
  loadNamespace("stringr")
  ret <- sapply(column, function(x) {
    ret <- stringr::str_c(x, collapse = sep)
    if(identical(ret, character(0))){
      # if it's character(0)
      NA
    } else {
      ret
    }
  })
  as.character(ret)
}

https://github.com/exploratory-io/exploratory_func/blob/master/LICENSE.md