Webscrape heading and lists to a dataframe with rvest - r

Question

I would like to scrape the hyperlinks on this webpage into a dataframe with the columns shown below. The source page contains headings and lists of links.
subject.heading (problem)
hyperlink.title (OK)
hyperlink (OK)
Getting the links and titles is straightforward (html_node "li" and "a"). I'm not clear how to incorporate the subject headings to the final dataframe.
library(tidyverse)
library(rvest)
my.url <- read_html("http://www.secnav.navy.mil/fmc/fmb/Pages/Fiscal-Year-2019.aspx") %>%
html_nodes("#sharePointMainContent")
hyperlink.title <- my.url %>%
html_nodes("li") %>%
html_text()
hyperlink <- my.url %>%
html_nodes("li") %>%
html_nodes("a") %>%
html_attr("href")
df <- tibble(title, hyperlink.title)
I can successfully scrape the headings, but cannot figure out how to incorporate them into the final dataframe properly.
subject.heading <- my.url %>%
html_nodes("h3") %>%
html_text() %>% str_trim()
Created on 2018-09-03 by the reprex package (v0.2.0).

Answer 1

That page has a weird structure, with tables inside the main table.
What I found to work is to iterate (map_df()) the cells of the parent table (identified by the s4-wpcell-plain class). Each cell contains another table, but we can simply extract what we are after, instead of relying on html_table().
library(tidyverse)
library(rvest)
#> Loading required package: xml2
r <- read_html("http://www.secnav.navy.mil/fmc/fmb/Pages/Fiscal-Year-2019.aspx") %>%
html_node("#sharePointMainContent>div>table") %>%
html_nodes(".s4-wpcell-plain") %>%
map_df(~{
heading <- .x %>% html_nodes('h3') %>% html_text() %>% str_trim()
titles <- .x %>% html_nodes('li') %>% html_text()
links <- .x %>% html_nodes('a') %>% html_attr("href")
data_frame(heading, titles, links)
})
r
#> # A tibble: 21 x 3
#> heading titles links
#> <chr> <chr> <chr>
#> 1 DEPARTMENT OF THE NAVY SUMMARY FY 19 DON Press Brief http://www.secna…
#> 2 DEPARTMENT OF THE NAVY SUMMARY Supporting Exhibits http://www.secna…
#> 3 DEPARTMENT OF THE NAVY SUMMARY Budget Highlights Book http://www.secna…
#> 4 DEPARTMENT OF THE NAVY SUMMARY The Bottom Line http://www.secna…
#> 5 DEPARTMENT OF THE NAVY SUMMARY Report to Congress on… http://www.secna…
#> 6 DEPARTMENT OF THE NAVY SUMMARY Ship Building Plan SE… http://www.secna…
#> 7 MILITARY PERSONNEL PROGRAMS Military Personnel, N… http://www.secna…
#> 8 MILITARY PERSONNEL PROGRAMS Military Personnel, M… http://www.secna…
#> 9 MILITARY PERSONNEL PROGRAMS Reserve Personnel, Na… http://www.secna…
#> 10 MILITARY PERSONNEL PROGRAMS Reserve Personnel, Ma… http://www.secna…
#> # ... with 11 more rows
Created on 2018-09-04 by the reprex package (v0.2.0).