Attualmente, gli strumenti I / O di Panda non mantengono un read_xml()
metodo e la controparte to_xml()
. Tuttavia, read_json
dimostra che le strutture ad albero possono essere implementate per l'importazione di dataframe e read_html
per i formati di markup.
Se la squadra panda fa considerare tale read_xml
metodo per una futura versione panda, che cosa sarebbe implementazione che perseguire: l'analisi con built-in xml.etree.ElementTree
con i suoi iterfind()
o iterparse()
funzioni o il modulo di terze parti, lxml
con la sua XPath 1.0 e XSLT 1.0 metodi?
Di seguito sono riportati i miei test eseguiti per quattro tipi di metodo su un input XML semplice, piatto e incentrato sugli elementi. Tutti sono impostati per l'analisi generalizzata per qualsiasi figlio di root di secondo livello e ogni metodo dovrebbe produrre esattamente lo stesso dataframe panda. Tutti tranne le ultime chiamate pd.Dataframe()
nell'elenco dei dizionari. Il metodo XSLT trasforma XML in CSV per il cast StringIO()
in pd.read_csv()
.
Domanda (in più parti)
PRESTAZIONI: come spieghi il più lento
iterparse
spesso consigliato per file più grandi poiché il file viene analizzato in modo iterativo? È in parte dovuto aiif
controlli logici?MEMORIA: la memoria della CPU è correlata ai tempi nelle chiamate I / O? XSLT e XPath 1.0 tendono a non scalare bene con documenti XML di dimensioni maggiori poiché l'intero file deve essere letto in memoria per essere analizzato.
STRATEGIA: l'elenco dei dizionari è una strategia ottimale per la
Dataframe()
chiamata? Guarda queste interessanti risposte: versione del generatore e una versione definita dall'utente iterwalk . Entrambi gli elenchi di upcast su dataframe.
Dati di input (gli attuali migliori utenti di Stack Overflow per anno di cui sono inclusi i nostri amici panda)
<?xml version="1.0" encoding="utf-8"?>
<stackoverflow>
<topusers>
<user>Gordon Linoff</user>
<link>http://www.stackoverflow.com//users/1144035/gordon-linoff</link>
<location>New York, United States</location>
<year_rep>5,985</year_rep>
<total_rep>499,408</total_rep>
<tag1>sql</tag1>
<tag2>sql-server</tag2>
<tag3>mysql</tag3>
</topusers>
<topusers>
<user>Günter Zöchbauer</user>
<link>http://www.stackoverflow.com//users/217408/g%c3%bcnter-z%c3%b6chbauer</link>
<location>Linz, Austria</location>
<year_rep>5,835</year_rep>
<total_rep>154,439</total_rep>
<tag1>angular2</tag1>
<tag2>typescript</tag2>
<tag3>javascript</tag3>
</topusers>
<topusers>
<user>jezrael</user>
<link>http://www.stackoverflow.com//users/2901002/jezrael</link>
<location>Bratislava, Slovakia</location>
<year_rep>5,740</year_rep>
<total_rep>83,237</total_rep>
<tag1>pandas</tag1>
<tag2>python</tag2>
<tag3>dataframe</tag3>
</topusers>
<topusers>
<user>VonC</user>
<link>http://www.stackoverflow.com//users/6309/vonc</link>
<location>France</location>
<year_rep>5,577</year_rep>
<total_rep>651,397</total_rep>
<tag1>git</tag1>
<tag2>github</tag2>
<tag3>docker</tag3>
</topusers>
<topusers>
<user>Martijn Pieters</user>
<link>http://www.stackoverflow.com//users/100297/martijn-pieters</link>
<location>Cambridge, United Kingdom</location>
<year_rep>5,337</year_rep>
<total_rep>525,176</total_rep>
<tag1>python</tag1>
<tag2>python-3.x</tag2>
<tag3>python-2.7</tag3>
</topusers>
<topusers>
<user>T.J. Crowder</user>
<link>http://www.stackoverflow.com//users/157247/t-j-crowder</link>
<location>United Kingdom</location>
<year_rep>5,258</year_rep>
<total_rep>508,310</total_rep>
<tag1>javascript</tag1>
<tag2>jquery</tag2>
<tag3>java</tag3>
</topusers>
<topusers>
<user>akrun</user>
<link>http://www.stackoverflow.com//users/3732271/akrun</link>
<location></location>
<year_rep>5,188</year_rep>
<total_rep>229,553</total_rep>
<tag1>r</tag1>
<tag2>dplyr</tag2>
<tag3>dataframe</tag3>
</topusers>
<topusers>
<user>Wiktor Stribi?ew</user>
<link>http://www.stackoverflow.com//users/3832970/wiktor-stribi%c5%bcew</link>
<location>Warsaw, Poland</location>
<year_rep>4,948</year_rep>
<total_rep>158,134</total_rep>
<tag1>regex</tag1>
<tag2>javascript</tag2>
<tag3>c#</tag3>
</topusers>
<topusers>
<user>Darin Dimitrov</user>
<link>http://www.stackoverflow.com//users/29407/darin-dimitrov</link>
<location>Sofia, Bulgaria</location>
<year_rep>4,936</year_rep>
<total_rep>709,683</total_rep>
<tag1>c#</tag1>
<tag2>asp.net-mvc</tag2>
<tag3>asp.net-mvc-3</tag3>
</topusers>
<topusers>
<user>Eric Duminil</user>
<link>http://www.stackoverflow.com//users/6419007/eric-duminil</link>
<location></location>
<year_rep>4,854</year_rep>
<total_rep>12,557</total_rep>
<tag1>ruby</tag1>
<tag2>ruby-on-rails</tag2>
<tag3>arrays</tag3>
</topusers>
<topusers>
<user>alecxe</user>
<link>http://www.stackoverflow.com//users/771848/alecxe</link>
<location>New York, United States</location>
<year_rep>4,723</year_rep>
<total_rep>233,368</total_rep>
<tag1>python</tag1>
<tag2>selenium</tag2>
<tag3>protractor</tag3>
</topusers>
<topusers>
<user>Jean-François Fabre</user>
<link>http://www.stackoverflow.com//users/6451573/jean-fran%c3%a7ois-fabre</link>
<location>Toulouse, France</location>
<year_rep>4,526</year_rep>
<total_rep>30,027</total_rep>
<tag1>python</tag1>
<tag2>python-3.x</tag2>
<tag3>python-2.7</tag3>
</topusers>
<topusers>
<user>piRSquared</user>
<link>http://www.stackoverflow.com//users/2336654/pirsquared</link>
<location>Bellevue, WA, United States</location>
<year_rep>4,482</year_rep>
<total_rep>41,183</total_rep>
<tag1>pandas</tag1>
<tag2>python</tag2>
<tag3>dataframe</tag3>
</topusers>
<topusers>
<user>CommonsWare</user>
<link>http://www.stackoverflow.com//users/115145/commonsware</link>
<location>Who Wants to Know?</location>
<year_rep>4,475</year_rep>
<total_rep>616,135</total_rep>
<tag1>android</tag1>
<tag2>java</tag2>
<tag3>android-intent</tag3>
</topusers>
<topusers>
<user>Quentin</user>
<link>http://www.stackoverflow.com//users/19068/quentin</link>
<location>United Kingdom</location>
<year_rep>4,464</year_rep>
<total_rep>509,365</total_rep>
<tag1>javascript</tag1>
<tag2>html</tag2>
<tag3>css</tag3>
</topusers>
<topusers>
<user>Jon Skeet</user>
<link>http://www.stackoverflow.com//users/22656/jon-skeet</link>
<location>Reading, United Kingdom</location>
<year_rep>4,348</year_rep>
<total_rep>921,690</total_rep>
<tag1>c#</tag1>
<tag2>java</tag2>
<tag3>.net</tag3>
</topusers>
<topusers>
<user>Felix Kling</user>
<link>http://www.stackoverflow.com//users/218196/felix-kling</link>
<location>Sunnyvale, CA</location>
<year_rep>4,324</year_rep>
<total_rep>411,535</total_rep>
<tag1>javascript</tag1>
<tag2>jquery</tag2>
<tag3>asynchronous</tag3>
</topusers>
<topusers>
<user>matt</user>
<link>http://www.stackoverflow.com//users/341994/matt</link>
<location></location>
<year_rep>4,313</year_rep>
<total_rep>220,515</total_rep>
<tag1>swift</tag1>
<tag2>ios</tag2>
<tag3>xcode</tag3>
</topusers>
<topusers>
<user>Psidom</user>
<link>http://www.stackoverflow.com//users/4983450/psidom</link>
<location>Atlanta, GA, United States</location>
<year_rep>4,236</year_rep>
<total_rep>36,950</total_rep>
<tag1>python</tag1>
<tag2>pandas</tag2>
<tag3>r</tag3>
</topusers>
<topusers>
<user>Martin R</user>
<link>http://www.stackoverflow.com//users/1187415/martin-r</link>
<location>Germany</location>
<year_rep>4,195</year_rep>
<total_rep>269,380</total_rep>
<tag1>swift</tag1>
<tag2>ios</tag2>
<tag3>swift3</tag3>
</topusers>
<topusers>
<user>Barmar</user>
<link>http://www.stackoverflow.com//users/1491895/barmar</link>
<location>Arlington, MA</location>
<year_rep>4,179</year_rep>
<total_rep>289,989</total_rep>
<tag1>javascript</tag1>
<tag2>php</tag2>
<tag3>jquery</tag3>
</topusers>
<topusers>
<user>Alexey Mezenin</user>
<link>http://www.stackoverflow.com//users/1227923/alexey-mezenin</link>
<location>??????</location>
<year_rep>4,142</year_rep>
<total_rep>31,602</total_rep>
<tag1>laravel</tag1>
<tag2>php</tag2>
<tag3>laravel-5.3</tag3>
</topusers>
<topusers>
<user>BalusC</user>
<link>http://www.stackoverflow.com//users/157882/balusc</link>
<location>Amsterdam, Netherlands</location>
<year_rep>4,046</year_rep>
<total_rep>703,046</total_rep>
<tag1>java</tag1>
<tag2>jsf</tag2>
<tag3>servlets</tag3>
</topusers>
<topusers>
<user>GurV</user>
<link>http://www.stackoverflow.com//users/6348498/gurv</link>
<location></location>
<year_rep>4,016</year_rep>
<total_rep>7,932</total_rep>
<tag1>sql</tag1>
<tag2>mysql</tag2>
<tag3>sql-server</tag3>
</topusers>
<topusers>
<user>Nina Scholz</user>
<link>http://www.stackoverflow.com//users/1447675/nina-scholz</link>
<location>Berlin, Deutschland</location>
<year_rep>3,950</year_rep>
<total_rep>61,135</total_rep>
<tag1>javascript</tag1>
<tag2>arrays</tag2>
<tag3>object</tag3>
</topusers>
<topusers>
<user>JB Nizet</user>
<link>http://www.stackoverflow.com//users/571407/jb-nizet</link>
<location>Saint-Etienne, France</location>
<year_rep>3,923</year_rep>
<total_rep>418,780</total_rep>
<tag1>java</tag1>
<tag2>hibernate</tag2>
<tag3>java-8</tag3>
</topusers>
<topusers>
<user>Frank van Puffelen</user>
<link>http://www.stackoverflow.com//users/209103/frank-van-puffelen</link>
<location>San Francisco, CA</location>
<year_rep>3,920</year_rep>
<total_rep>86,520</total_rep>
<tag1>firebase</tag1>
<tag2>firebase-database</tag2>
<tag3>android</tag3>
</topusers>
<topusers>
<user>dasblinkenlight</user>
<link>http://www.stackoverflow.com//users/335858/dasblinkenlight</link>
<location>United States</location>
<year_rep>3,886</year_rep>
<total_rep>475,813</total_rep>
<tag1>c#</tag1>
<tag2>java</tag2>
<tag3>c++</tag3>
</topusers>
<topusers>
<user>Tim Biegeleisen</user>
<link>http://www.stackoverflow.com//users/1863229/tim-biegeleisen</link>
<location>Singapore</location>
<year_rep>3,814</year_rep>
<total_rep>77,211</total_rep>
<tag1>sql</tag1>
<tag2>mysql</tag2>
<tag3>java</tag3>
</topusers>
<topusers>
<user>Greg Hewgill</user>
<link>http://www.stackoverflow.com//users/893/greg-hewgill</link>
<location>Christchurch, New Zealand</location>
<year_rep>3,796</year_rep>
<total_rep>529,137</total_rep>
<tag1>git</tag1>
<tag2>python</tag2>
<tag3>git-pull</tag3>
</topusers>
<topusers>
<user>unutbu</user>
<link>http://www.stackoverflow.com//users/190597/unutbu</link>
<location></location>
<year_rep>3,735</year_rep>
<total_rep>401,595</total_rep>
<tag1>python</tag1>
<tag2>pandas</tag2>
<tag3>numpy</tag3>
</topusers>
<topusers>
<user>Hans Passant</user>
<link>http://www.stackoverflow.com//users/17034/hans-passant</link>
<location>Madison, WI</location>
<year_rep>3,688</year_rep>
<total_rep>672,118</total_rep>
<tag1>c#</tag1>
<tag2>.net</tag2>
<tag3>winforms</tag3>
</topusers>
<topusers>
<user>Jonathan Leffler</user>
<link>http://www.stackoverflow.com//users/15168/jonathan-leffler</link>
<location>California, USA</location>
<year_rep>3,649</year_rep>
<total_rep>455,157</total_rep>
<tag1>c</tag1>
<tag2>bash</tag2>
<tag3>unix</tag3>
</topusers>
<topusers>
<user>paxdiablo</user>
<link>http://www.stackoverflow.com//users/14860/paxdiablo</link>
<location></location>
<year_rep>3,636</year_rep>
<total_rep>507,043</total_rep>
<tag1>c</tag1>
<tag2>c++</tag2>
<tag3>bash</tag3>
</topusers>
<topusers>
<user>Pranav C Balan</user>
<link>http://www.stackoverflow.com//users/3037257/pranav-c-balan</link>
<location>Ramanthali, Kannur, Kerala, India</location>
<year_rep>3,604</year_rep>
<total_rep>64,476</total_rep>
<tag1>javascript</tag1>
<tag2>jquery</tag2>
<tag3>html</tag3>
</topusers>
<topusers>
<user>Suragch</user>
<link>http://www.stackoverflow.com//users/3681880/suragch</link>
<location>Hohhot, China</location>
<year_rep>3,580</year_rep>
<total_rep>71,032</total_rep>
<tag1>swift</tag1>
<tag2>ios</tag2>
<tag3>android</tag3>
</topusers>
</stackoverflow>
Metodi Python
import xml.etree.ElementTree as et
import pandas as pd
from io import StringIO
from lxml import etree as lxet
def read_xml_iterfind():
tree = et.parse('Input.xml')
data = []
inner = {}
for el in tree.iterfind('./*'):
for i in el.iterfind('*'):
inner[i.tag] = i.text
data.append(inner)
inner = {}
df = pd.DataFrame(data)
def read_xml_iterparse():
data = []
inner = {}
i = 1
for (ev, el) in et.iterparse(path):
if i <= 2:
first_tag = el.tag
if el.tag == first_tag and len(inner) != 0:
data.append(inner)
inner = {}
if el.text is not None and len(el.text.strip()) > 0:
inner[el.tag] = el.text
i += 1
df = pd.DataFrame(data)
def read_xml_lxml_xpath():
tree = lxet.parse('Input.xml')
data = []
inner = {}
for el in tree.xpath('/*/*'):
for i in el:
inner[i.tag] = i.text
data.append(inner)
inner = {}
df = pd.DataFrame(data)
def read_xml_lxml_xsl():
xml = lxet.parse('Input.xml')
xslstr = '''
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output version="1.0" encoding="UTF-8" indent="yes" method="text"/>
<xsl:strip-space elements="*"/>
<!-- HEADERS -->
<xsl:template match = "/*">
<xsl:for-each select="*[1]/*">
<xsl:value-of select="local-name()" />
<xsl:choose>
<xsl:when test="position() != last()">
<xsl:text>,</xsl:text>
</xsl:when>
<xsl:otherwise>
<xsl:text>
</xsl:text>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each>
<xsl:apply-templates/>
</xsl:template>
<!-- DATA ROWS (COMMA-SEPARATED) -->
<xsl:template match="/*/*" priority="2">
<xsl:for-each select="*">
<xsl:if test="position() = 1">
<xsl:text>"</xsl:text>
</xsl:if>
<xsl:value-of select="." />
<xsl:choose>
<xsl:when test="position() != last()">
<xsl:text>","</xsl:text>
</xsl:when>
<xsl:otherwise>
<xsl:text>"
</xsl:text>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each>
</xsl:template>
</xsl:transform>
'''
xsl = lxet.fromstring(xslstr)
transform = lxet.XSLT(xsl)
newdom = transform(xml)
df = pd.read_csv(StringIO(str(newdom)))
Tempistiche (con XML e XML correnti con 25 volte i figli (ad esempio, 900 record utente StackOverflow)
# SHORTER FILE
python -mtimeit -s'import readxml_test_runs as test' 'test.read_xml_iterfind()'
100 loops, best of 3: 3.87 msec per loop
python -mtimeit -s'import readxml_test_runs as test' 'test.read_xml_iterparse()'
100 loops, best of 3: 5.5 msec per loop
python -mtimeit -s'import readxml_test_runs as test' 'test.read_xml_lxml_xpath()'
100 loops, best of 3: 3.86 msec per loop
python -mtimeit -s'import readxml_test_runs as test' 'test.read_xml_lxml_xsl()'
100 loops, best of 3: 5.68 msec per loop
# LARGER FILE
python -mtimeit -n'100' -s'import readxml_test_runs as test' 'test.read_xml_iterfind()'
100 loops, best of 3: 36 msec per loop
python -mtimeit -n'100' -s'import readxml_test_runs as test' 'test.read_xml_iterparse()'
100 loops, best of 3: 78.9 msec per loop
python -mtimeit -n'100' -s'import readxml_test_runs as test' 'test.read_xml_lxml_xpath()'
100 loops, best of 3: 32.7 msec per loop
python -mtimeit -n'100' -s'import readxml_test_runs as test' 'test.read_xml_lxml_xsl()'
100 loops, best of 3: 51.4 msec per loop