how to bind the col names as first row to each data.frame in a list

Question

I have a list of list, which each sublist also have multi dfs. I would like to bind names(df) to df. How can I do that?

Data:

q1<-list(Demographics = list(`101-01-101` = structure(list(SubjectID = "101-01-101", 
    BRTHDTC = "1953-07-07", SEX = "Female"), row.names = c(NA, 
-1L), class = c("tbl_df", "tbl", "data.frame")), `101-02-102` = structure(list(
    SubjectID = "101-02-102", BRTHDTC = "1963-07-02", SEX = "Female"), row.names = c(NA, 
-1L), class = c("tbl_df", "tbl", "data.frame")), `101-03-103` = structure(list(
    SubjectID = "101-03-103", BRTHDTC = "1940-09-11", SEX = "Male"), row.names = c(NA, 
-1L), class = c("tbl_df", "tbl", "data.frame")), `101-04-104` = structure(list(
    SubjectID = "101-04-104", BRTHDTC = "1955-12-31", SEX = "Male"), row.names = c(NA, 
-1L), class = c("tbl_df", "tbl", "data.frame")), `104-05-201` = structure(list(
    SubjectID = "104-05-201", BRTHDTC = "1950-12-04", SEX = "Female"), row.names = c(NA, 
-1L), class = c("tbl_df", "tbl", "data.frame"))), DiseaseStatus = list(
    `101-01-101` = structure(list(SubjectID = "101-01-101", DSDT = "2016-03-14", 
        DSDT_P = NA_character_), row.names = c(NA, -1L), class = c("tbl_df", 
    "tbl", "data.frame")), `101-02-102` = structure(list(SubjectID = "101-02-102", 
        DSDT = "2017-04-04", DSDT_P = NA_character_), row.names = c(NA, 
    -1L), class = c("tbl_df", "tbl", "data.frame")), `101-03-103` = structure(list(
        SubjectID = "101-03-103", DSDT = NA_character_, DSDT_P = "UN-UNK-2015"), row.names = c(NA, 
    -1L), class = c("tbl_df", "tbl", "data.frame")), `101-04-104` = structure(list(
        SubjectID = "101-04-104", DSDT = "2016-05-02", DSDT_P = NA_character_), row.names = c(NA, 
    -1L), class = c("tbl_df", "tbl", "data.frame")), `104-05-201` = structure(list(
        SubjectID = "104-05-201", DSDT = "2018-07-06", DSDT_P = NA_character_), row.names = c(NA, 
    -1L), class = c("tbl_df", "tbl", "data.frame"))))

My codes doesn't work:

q2<-imap(q1, ~ map(.x, ~
 .x %>%
 map(~ bind_rows(names(.x), .x) )))

My expected outcome is sth that looks like this:

Can you give an example of the output you want? I'm not much good with *purrr* but is something like `lapply(q1, function(x) do.call(rbind, Map(replace, x, "source", names(x))) )` the desired goal? — thelatemail, May 27 '21 at 00:42
So like `lapply(q1, function(x) Map(rbind, lapply(x, colnames), x) )` ? - it's going to break your datasets and convert everything to character, but if that's what you need. — thelatemail, May 27 '21 at 00:58
I would like to keep the list of list as is, just add extra row which equal to the names of col — Stataq, May 27 '21 at 01:00
It'll still be a list with the exact same structure using that code I posted, but it's a very non-standard way of storing that information. — thelatemail, May 27 '21 at 01:02

score 4 · Accepted Answer · answered May 27 '21 at 01:18

4

Base R using lapply -

lapply(q1, function(x) lapply(x, function(y) rbind(names(y), y)))

#$Demographics
#$Demographics$`101-01-101`
# A tibble: 2 x 3
#  SubjectID  BRTHDTC    SEX   
#  <chr>      <chr>      <chr> 
#1 SubjectID  BRTHDTC    SEX   
#2 101-01-101 1953-07-07 Female

#$Demographics$`101-02-102`
# A tibble: 2 x 3
#  SubjectID  BRTHDTC    SEX   
#  <chr>      <chr>      <chr> 
#1 SubjectID  BRTHDTC    SEX   
#2 101-02-102 1963-07-02 Female
#...
#...

Your attempt was close but it needs few changes -

You don't need 3 map's
bind_rows needs a dataframe or tibble to combine. names(.x) is a character vector so we can use rbind.

library(purrr)
map(q1, function(x) map(x, ~rbind(names(.x), .x)))

answered May 27 '21 at 01:18

Ronak Shah

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why the choice for an anonymous function in your purrr method? Isnt it possible to call nested lambda functions? Like in `map(q1, ~map(.x, ~rbind(names(.x), .x)))`. will the `.x(......, .x` get one into trouble? – GuedesBF May 27 '21 at 02:20
1

It is possible but I think it can be confusing. Also if we want to use `.x` from the outer `map` in the inner one we can't use that. Although, it is not applicable in this example. – Ronak Shah May 27 '21 at 02:25

Sinh Nguyen · Answer 2 · 2021-05-27T01:05:40.647

Here is a try.

library(purrr)
library(dplyr)

# First map the bind_rows function to each sub-list of your list of two
q2 <- imap(q1, ~ map(.x, 
  .f = function(x) {
    name_df <- tibble(a = names(x), b = names(x)) %>%
      pivot_wider(names_from = a, values_from = b)
    data <- bind_rows(name_df, x)
  }))
q2
#> $Demographics
#> $Demographics$`101-01-101`
#> # A tibble: 2 x 3
#>   SubjectID  BRTHDTC    SEX   
#>   <chr>      <chr>      <chr> 
#> 1 SubjectID  BRTHDTC    SEX   
#> 2 101-01-101 1953-07-07 Female
#> 
#> $Demographics$`101-02-102`
#> # A tibble: 2 x 3
#>   SubjectID  BRTHDTC    SEX   
#>   <chr>      <chr>      <chr> 
#> 1 SubjectID  BRTHDTC    SEX   
#> 2 101-02-102 1963-07-02 Female
#> 
#> $Demographics$`101-03-103`
#> # A tibble: 2 x 3
#>   SubjectID  BRTHDTC    SEX  
#>   <chr>      <chr>      <chr>
#> 1 SubjectID  BRTHDTC    SEX  
#> 2 101-03-103 1940-09-11 Male 
#> 
#> $Demographics$`101-04-104`
#> # A tibble: 2 x 3
#>   SubjectID  BRTHDTC    SEX  
#>   <chr>      <chr>      <chr>
#> 1 SubjectID  BRTHDTC    SEX  
#> 2 101-04-104 1955-12-31 Male 
#> 
#> $Demographics$`104-05-201`
#> # A tibble: 2 x 3
#>   SubjectID  BRTHDTC    SEX   
#>   <chr>      <chr>      <chr> 
#> 1 SubjectID  BRTHDTC    SEX   
#> 2 104-05-201 1950-12-04 Female
#> 
#> 
#> $DiseaseStatus
#> $DiseaseStatus$`101-01-101`
#> # A tibble: 2 x 3
#>   SubjectID  DSDT       DSDT_P
#>   <chr>      <chr>      <chr> 
#> 1 SubjectID  DSDT       DSDT_P
#> 2 101-01-101 2016-03-14 <NA>  
#> 
#> $DiseaseStatus$`101-02-102`
#> # A tibble: 2 x 3
#>   SubjectID  DSDT       DSDT_P
#>   <chr>      <chr>      <chr> 
#> 1 SubjectID  DSDT       DSDT_P
#> 2 101-02-102 2017-04-04 <NA>  
#> 
#> $DiseaseStatus$`101-03-103`
#> # A tibble: 2 x 3
#>   SubjectID  DSDT  DSDT_P     
#>   <chr>      <chr> <chr>      
#> 1 SubjectID  DSDT  DSDT_P     
#> 2 101-03-103 <NA>  UN-UNK-2015
#> 
#> $DiseaseStatus$`101-04-104`
#> # A tibble: 2 x 3
#>   SubjectID  DSDT       DSDT_P
#>   <chr>      <chr>      <chr> 
#> 1 SubjectID  DSDT       DSDT_P
#> 2 101-04-104 2016-05-02 <NA>  
#> 
#> $DiseaseStatus$`104-05-201`
#> # A tibble: 2 x 3
#>   SubjectID  DSDT       DSDT_P
#>   <chr>      <chr>      <chr> 
#> 1 SubjectID  DSDT       DSDT_P
#> 2 104-05-201 2018-07-06 <NA>

^{Created on 2021-05-27 by the reprex package (v2.0.0)}

To explain further why your code is not work:

imap is apply your map to each list
map is apply to each column of each df in each list - and that causing the errors as the code map the bind_rows function to records of each column (a vector)

Here is what your code do if replace bind_rows with print. It printed out each record of the each column in each df within each list.

q2<-imap(q1, ~ map(.x, ~
    .x %>%
    map(~ print(.x))))
#> [1] "101-01-101"
#> [1] "1953-07-07"
#> [1] "Female"
#> [1] "101-02-102"
#> [1] "1963-07-02"
#> [1] "Female"
#> [1] "101-03-103"
#> [1] "1940-09-11"
#> [1] "Male"
#> [1] "101-04-104"
#> [1] "1955-12-31"
#> [1] "Male"
#> [1] "104-05-201"
#> [1] "1950-12-04"
#> [1] "Female"
#> [1] "101-01-101"
#> [1] "2016-03-14"
#> [1] NA
#> [1] "101-02-102"
#> [1] "2017-04-04"
#> [1] NA
#> [1] "101-03-103"
#> [1] NA
#> [1] "UN-UNK-2015"
#> [1] "101-04-104"
#> [1] "2016-05-02"
#> [1] NA
#> [1] "104-05-201"
#> [1] "2018-07-06"
#> [1] NA

^{Created on 2021-05-27 by the reprex package (v2.0.0)}

Thanks. however I only want col names bind with col, so the fist row of the data will be the same as col name. I will still have the same list of list — Stataq, May 27 '21 at 00:45
Please check the update - as I added the output of the map and remove the join :) — Sinh Nguyen, May 27 '21 at 00:47
Thanks. I think my request might be a little bit strange,. So I just posted an expected outcome. :D — Stataq, May 27 '21 at 00:51

how to bind the col names as first row to each data.frame in a list

2 Answers2