pandas read_html function with colspan=2

Question

I’m using the pandas read_html function to load an html table into a dataframe, however it’s failing because the source data has a colspan=2 merged header, resulting in this AssertionError: 6 columns passed, passed data had 7 columns.

I’ve tried various options with the header kwarg (header=None, header=[‘Code’…]) but nothing seems to work.

Does anyone know of any way to parse and html table with merged columns using pandas read_html?

Asked By: MarkNS

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Source

Answer 1

If you don’t insist on using read_html from pandas, this code does the job:

import pandas as pd
from lxml.html import parse
from urllib2 import urlopen
from pandas.io.parsers import TextParser

def _unpack(row, kind='td'):
   elts = row.findall('.//%s' % kind)
   return [val.text_content() for val in elts]

def parse_options_data(table):
  rows = table.findall('.//tr')
  header = _unpack(rows[0], kind='th')
  data = [_unpack(r) for r in rows[1:]]
  return TextParser(data, names=header).get_chunk()

parsed = parse(urlopen('http://www.bmfbovespa.com.br/en-us/intros/Limits-and-Haircuts-for-accepting-stocks-as-collateral.aspx?idioma=en-us'))
doc = parsed.getroot()
tables = doc.findall('.//table')
table = parse_options_data(tables[0])

This is taken from the Book “Python for Data analysis” from Wes McKinney.

Answered By: Martin Böschen

Answer 2

pandas >= 0.24.0 understands colspan and rowspan attributes. As per the
release
notes:

result = pd.read_html("""
    <table>
      <thead>
        <tr>
          <th>A</th><th>B</th><th>C</th>
        </tr>
      </thead>
      <tbody>
        <tr>
          <td colspan="2">1</td><td>2</td>
        </tr>
      </tbody>
    </table>""")

result

Out:

[   A  B  C
 0  1  1  2

Previously this would return the following:

[   A  B   C
 0  1  2 NaN]

I can’t test with your link because the URL is not found.

Answered By: joelostblom

pandas read_html function with colspan=2

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