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PERF: read_html: Reading one HTML file with multiple tables is much slower than loading each table separatly #49942

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Merged
mroeschke merged 5 commits into from
Nov 29, 2022
+3 −2
Merged

PERF: read_html: Reading one HTML file with multiple tables is much slower than loading each table separatly #49942

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5db1ff9
change xpath expression - perf improvement
asishm Nov 28, 2022
95f564a
gh ref
asishm Nov 28, 2022
32b637a
Merge branch 'main' into read_html_perf
asishm Nov 28, 2022
8ec8777
add whatsnew
asishm Nov 29, 2022
0fc8b46
Merge branch 'read_html_perf' of github.com:asishm/pandas into read_h…
asishm Nov 29, 2022
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v2.0.0.rst
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Expand Up @@ -613,6 +613,7 @@ Performance improvements
- Performance improvement in :func:`read_stata` with parameter ``index_col`` set to ``None`` (the default). Now the index will be a :class:`RangeIndex` instead of :class:`Int64Index` (:issue:`49745`)
- Performance improvement in :func:`merge` when not merging on the index - the new index will now be :class:`RangeIndex` instead of :class:`Int64Index` (:issue:`49478`)
- Performance improvement in :meth:`DataFrame.to_dict` and :meth:`Series.to_dict` when using any non-object dtypes (:issue:`46470`)
- Performance improvement in :func:`read_html` when there are multiple tables (:issue:`49929`)

.. ---------------------------------------------------------------------------
.. _whatsnew_200.bug_fixes:
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4 changes: 2 additions & 2 deletions pandas/io/html.py
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Expand Up @@ -744,8 +744,8 @@ def _parse_tables(self, doc, match, kwargs):
pattern = match.pattern

# 1. check all descendants for the given pattern and only search tables
# 2. go up the tree until we find a table
xpath_expr = f"//table//*[re:test(text(), {repr(pattern)})]/ancestor::table"
# GH 49929
xpath_expr = f"//table[.//text()[re:test(., {repr(pattern)})]]"

# if any table attributes were given build an xpath expression to
# search for them
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