Tables and lists

In zuhtml: Parse 'HTML' with a Bundled 'Gumbo' Parser

knitr::opts_chunk$set(collapse = TRUE, comment = "#>")

library(zuhtml)

Tables

html_table() reads one <table> into a data frame; html_tables() finds tables and reads each. Every column is character, so identifiers keep their leading zeros.

doc <- html_parse("
<table>
  <thead><tr><th>Code<th>Price</thead>
  <tr><td>0012<td>12.50
  <tr><td>0034<td>9.00
</table>")
html_table(html_element(doc, "table"))

Spans

A value that spans rows or columns is repeated in every slot it covers, and a column's name joins the header rows above it with " / ":

doc <- html_parse("
<table>
  <tr><th rowspan=2>Region<th colspan=2>Sales
  <tr><th>2025<th>2026
  <tr><td>North<td>10<td>12
  <tr><td rowspan=2>South<td>7<td>9
  <tr><td>8<td>11
</table>")
html_table(html_element(doc, "table"))

rowspan="0" runs to the end of its row group, and a rowspan larger than the rows left in its group is cut there. Two cells whose spans cover the same slot are an error, not a silent overwrite:

doc <- html_parse("<table><tr><td>a<td rowspan=2>b<tr><td colspan=2>c</table>")
try(html_table(html_element(doc, "table")))

Headers

With the default header = "auto", the rows of <thead> are headers if there is one, otherwise the leading rows made only of <th> cells. A <th> among <td>s is a row label, not a header. Use TRUE, FALSE or row numbers to choose explicitly:

doc <- html_parse("<table><tr><td>name<td>qty<tr><td>tea<td>2</table>")
tab <- html_element(doc, "table")
html_table(tab)
html_table(tab, header = TRUE)

Blank names become V1, V2, ...; duplicate names get make.unique() suffixes. Rows are read head first, then bodies, then footers, and footers are data. Rows of a table nested inside a cell stay out of the outer table, and the nested table's text stays out of the cell.

Missing slots (in ragged rows) are NA; an empty cell is "". Mark placeholders as missing with na:

doc <- html_parse("<table><tr><th>a<th>b<tr><td>1<td>-<tr><td>2</table>")
html_table(html_element(doc, "table"), na = "-")

Lists

html_list() reads one <ul> or <ol>. Each item's text leaves out the lists nested inside it:

doc <- html_parse("
<ul>
  <li>Fruit
    <ul><li>Apple<li>Pear</ul>
  <li>Tools
    <div><ol><li>Hammer<li>Saw</ol></div>
</ul>")
menu <- html_element(doc, "ul")
html_list(menu)

mode = "tree" keeps the nesting, including lists inside wrapper elements such as the <div> above:

tree <- html_list(menu, mode = "tree")
tree
tree$items[[2]]$children[[1]]$type

To read many lists, lapply() over a nodeset passes one node at a time:

lapply(html_elements(doc, "ul ul, ol"), html_list)

zuhtml documentation built on Oct. 6, 2026, 5:06 p.m.