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library(openalexR)
library(dplyr)
#> Error in get(paste0(generic, ".", class), envir = get_method_env()) : 
#>   object 'type_sum.accel' not found

The default output from an oa_fetch call is a tibble. This object type allows each row to be one unit of entity (article, institution, etc.), which is often helpful for downstream wrangling. It simplifies and combines complex output elements in list columns, which can be extracted or exploded with dplyr::rowwise or purrr::map.

IMPORTANT: Although the list-to-tibble conversion can be trivial, in “flattening” the list output to a tibble, we took the opinionated approach and made a few decisions to simplify the original nested list such as retaining only a subset of the fields of Works (details in oa_df source code). If you think that everyone would benefit from an additional field being returned in the final dataframe, please open an issue.

While the tibble output is sufficient in most use cases, you may need to obtain the original nested list with all the information on an entity for your special research problem. If so, please specify output = "list" in your oa_fetch call. Then, you can wrangle the list output however you like, for example:

x <- oa_fetch(
  identifier = c("A5023888391", "A5042522694"),
  output = "list"
)
d <- rrapply::rrapply(x, how = "melt")    
head(d)
#>   L1                        L2   L3   L4   L5   L6
#> 1  1                        id <NA> <NA> <NA> <NA>
#> 2  1                     orcid <NA> <NA> <NA> <NA>
#> 3  1              display_name <NA> <NA> <NA> <NA>
#> 4  1 display_name_alternatives    1 <NA> <NA> <NA>
#> 5  1 display_name_alternatives    2 <NA> <NA> <NA>
#> 6  1 display_name_alternatives    3 <NA> <NA> <NA>
#>                                   value
#> 1      https://openalex.org/A5042522694
#> 2 https://orcid.org/0000-0002-1298-3089
#> 3                         David Tarragó
#> 4                            D. Tarragó
#> 5                 David Tarragó Asensio
#> 6                            D. Tarrago

Example 1: institutions

Suppose we queried Open Alex to obtain information on large Canadian institutions and now want to extract their latitudes and longitudes.

institutions <- oa_fetch(
  entity = "institutions",
  country_code = "CA",
  cited_by_count = ">4000000",
  verbose = TRUE,
  count_only = FALSE
)
#> Requesting url: https://api.openalex.org/institutions?filter=country_code%3ACA%2Ccited_by_count%3A%3E4000000
#> Getting 1 page of results with a total of 10 records...
#> Warning: Note: `oa_fetch` and `oa2df` now return new names for some columns in openalexR v2.0.0.
#>     See NEWS.md for the list of changes.
#>     Call `get_coverage()` to view the all updated columns and their original names in OpenAlex.
#> This warning is displayed once every 8 hours.

head(institutions)
#> # A tibble: 6 × 22
#>   id                   display_name display_name_alterna…¹ display_name_acronyms
#>   <chr>                <chr>        <list>                 <list>               
#> 1 https://openalex.or… University … <chr [1]>              <lgl [1]>            
#> 2 https://openalex.or… University … <chr [1]>              <chr [1]>            
#> 3 https://openalex.or… McGill Univ… <chr [1]>              <lgl [1]>            
#> 4 https://openalex.or… University … <chr [2]>              <lgl [1]>            
#> 5 https://openalex.or… University … <chr [1]>              <chr [1]>            
#> 6 https://openalex.or… Université … <chr [2]>              <chr [1]>            
#> # ℹ abbreviated name: ¹​display_name_alternatives
#> # ℹ 18 more variables: international_display_name <list>, ror <chr>,
#> #   ids <list>, country_code <chr>, geo <list>, type <chr>, homepage_url <chr>,
#> #   image_url <chr>, image_thumbnail_url <chr>, associated_institutions <list>,
#> #   works_count <int>, cited_by_count <int>, counts_by_year <list>,
#> #   summary_stats <list>, works_api_url <chr>, topics <list>,
#> #   updated_date <chr>, created_date <chr>

We present three different approaches below.

dplyr::rowwise

The use of rowwise used to be discouraged, but the tidyverse team has now recognized its importance in many workflows, and so rowwise is here to stay. We think rowwise pairs very naturally with our list columns output.

institutions %>%
  rowwise() %>%
  mutate(
    name = display_name,
    openalex = stringr::str_extract(id, "I\\d+"),
    lat = geo$latitude,
    lon = geo$longitude,
    .keep = "none"
  )
#> # A tibble: 10 × 4
#> # Rowwise: 
#>    name                           openalex     lat    lon
#>    <chr>                          <chr>      <dbl>  <dbl>
#>  1 University of Toronto          I185261750  43.7  -79.4
#>  2 University of British Columbia I141945490  49.2 -123. 
#>  3 McGill University              I5023651    45.5  -73.6
#>  4 University of Alberta          I154425047  53.6 -113. 
#>  5 University of Calgary          I168635309  51.1 -114. 
#>  6 Université de Montréal         I70931966   45.5  -73.6
#>  7 McMaster University            I98251732   43.3  -79.8
#>  8 University of Ottawa           I153718931  45.4  -75.7
#>  9 Western University             I125749732  43.0  -81.2
#> 10 University of Waterloo         I151746483  43.5  -80.5

purrr::map

Alternatively, you can use any function in the purrr::map family. As you can see below, the syntax is a little less natural, but you may gain some performance advantage if you have a really large dataframe.

institutions %>%
  mutate(
    name = display_name,
    openalex = stringr::str_extract(id, "I\\d+"),
    lat = purrr::map_dbl(geo, ~ .x$latitude),
    lon = purrr::map_dbl(geo, ~ .x$longitude),
    .keep = "none"
  )
#> # A tibble: 10 × 4
#>    name                           openalex     lat    lon
#>    <chr>                          <chr>      <dbl>  <dbl>
#>  1 University of Toronto          I185261750  43.7  -79.4
#>  2 University of British Columbia I141945490  49.2 -123. 
#>  3 McGill University              I5023651    45.5  -73.6
#>  4 University of Alberta          I154425047  53.6 -113. 
#>  5 University of Calgary          I168635309  51.1 -114. 
#>  6 Université de Montréal         I70931966   45.5  -73.6
#>  7 McMaster University            I98251732   43.3  -79.8
#>  8 University of Ottawa           I153718931  45.4  -75.7
#>  9 Western University             I125749732  43.0  -81.2
#> 10 University of Waterloo         I151746483  43.5  -80.5

base::lapply

Similar to the purrr approach, you can use the base functions in the lapply family, for example:

institutions %>%
  mutate(
    name = display_name,
    openalex = stringr::str_extract(id, "I\\d+"),
    lat = vapply(geo, function(x) x$latitude, numeric(1)),
    lon = vapply(geo, function(x) x$longitude, numeric(1)),
    .keep = "none"
  )
#> # A tibble: 10 × 4
#>    name                           openalex     lat    lon
#>    <chr>                          <chr>      <dbl>  <dbl>
#>  1 University of Toronto          I185261750  43.7  -79.4
#>  2 University of British Columbia I141945490  49.2 -123. 
#>  3 McGill University              I5023651    45.5  -73.6
#>  4 University of Alberta          I154425047  53.6 -113. 
#>  5 University of Calgary          I168635309  51.1 -114. 
#>  6 Université de Montréal         I70931966   45.5  -73.6
#>  7 McMaster University            I98251732   43.3  -79.8
#>  8 University of Ottawa           I153718931  45.4  -75.7
#>  9 Western University             I125749732  43.0  -81.2
#> 10 University of Waterloo         I151746483  43.5  -80.5

Example 2: works

Suppose we have a tibble of works output and would like to find the institutions corresponding with the works’ authors. In this case, each work may have more than one affiliated institutions.

Tibble output

Assuming that each author is affiliated with only one institution, we can call oa_fetch with the default output = "tibble":

works <- oa_fetch(
  entity = "works",
  title.search = c("bibliometric analysis", "science mapping"),
  cited_by_count = ">100",
  from_publication_date = "2020-01-01",
  to_publication_date = "2021-01-31",
  options = list(sort = "cited_by_count:desc"),
  count_only = FALSE
)

We will store the result in a list column:

multi_insts <- works %>%
  rowwise() %>%
  mutate(
    openalex = stringr::str_extract(id, "W\\d+"),
    institutions = list(unique(authorships$institution_display_name)),
    .keep = "none"
  )
#> Warning: There were 82 warnings in `mutate()`.
#> The first warning was:
#>  In argument: `institutions =
#>   list(unique(authorships$institution_display_name))`.
#>  In row 1.
#> Caused by warning:
#> ! Unknown or uninitialised column: `institution_display_name`.
#>  Run `dplyr::last_dplyr_warnings()` to see the 81 remaining warnings.

multi_insts
#> # A tibble: 82 × 2
#> # Rowwise: 
#>    openalex    institutions
#>    <chr>       <list>      
#>  1 W3001491100 <NULL>      
#>  2 W3038273726 <NULL>      
#>  3 W3044902155 <NULL>      
#>  4 W3042215340 <NULL>      
#>  5 W2998021954 <NULL>      
#>  6 W3003683721 <NULL>      
#>  7 W3005144120 <NULL>      
#>  8 W3011866596 <NULL>      
#>  9 W3000049009 <NULL>      
#> 10 W3025370095 <NULL>      
#> # ℹ 72 more rows

# institutions of the first work
str(multi_insts[1, "institutions"])
#> rowws_df [1 × 1] (S3: rowwise_df/tbl_df/tbl/data.frame)
#>  $ institutions:List of 1
#>   ..$ : NULL
#>  - attr(*, "groups")= tibble [1 × 1] (S3: tbl_df/tbl/data.frame)
#>   ..$ .rows: list<int> [1:1] 
#>   .. ..$ : int 1
#>   .. ..@ ptype: int(0)

List output

If we want to get all the institutions that the authors of these works are affiliated with (since one author may be affiliated with more than one institution), you would want to work with the list output.

As you can see, the nested list can be more convoluted to work with:

works_list <- oa_fetch(
  entity = "works",
  title.search = c("bibliometric analysis", "science mapping"),
  cited_by_count = ">100",
  from_publication_date = "2020-01-01",
  to_publication_date = "2021-01-31",
  options = list(sort = "cited_by_count:desc"),
  output = "list"
)

work_authors <- lapply(works_list, \(x) x$authorships)

unique_insts <- sapply(
  work_authors,
  \(z) unique(unlist(
    sapply(
      z, \(y) sapply(y$institutions, \(x) x$display_name)
    )
  ))
)

unique_insts[[1]]
#> [1] "Universidad de Cádiz"                 
#> [2] "Universidad de Granada"               
#> [3] "Hospital Universitario Puerta del Mar"