Save a data frame with list-columns as csv file

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清歌不尽
清歌不尽 2021-02-09 06:01

I have the following data frame that looks like this (3 columns as list).

A tibble: 14 x 4
                                                    clinic_name drop_         


        
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  • 2021-02-09 06:34

    Here's another option that may be a little simpler.

    Depending on the data, comma separated values could get complicated, so I'm using a bar | for separating values in list columns:

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

    starwars is one of the dplyr sample dataframes.

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  • 2021-02-09 06:41

    exploratory::list_to_text() will convert a list column to a character column. The default is sep = ", ", which I recommend changing to something else if writing to a .csv.

    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

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  • 2021-02-09 06:51

    Create a tibble containing list columns:

    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)
    

    Write a general-purpose function that converts any list columns to character type:

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

    Apply function to tibble with list columns:

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

    Write newly formatted dataframe as csv file:

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

    This is a csv file with the list columns expanded as regular strings.

    Here is an all-encompassing function. Just pass in your tibble and a filename:

    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)
    }
    

    Usage:

    tibble_with_lists_to_csv(tibb, '~/Desktop/tibb.csv')
    
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  • 2021-02-09 06:54

    I had a similar dataframe with list columns that I wanted to save as csv. I figured out this method. As well as how to turn the columns back into lists.

    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))))
    
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  • 2021-02-09 06:54

    Is there any specific reason why you would like to save the columns as a list ? Alternatively, you can use unnest and save it in csv. example below

    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")
    

    further, when you read the file you can nest it back

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