Question

Given a large array of numbers where:

[1, 2, 3, 4 ...] => <tag attrib="1" />
                    <tag attrib="2" />
                    <tag attrib="3" />
                    <tag attrib="4" />
                    ...

Which is more efficient/fast:

a) building them from scratch using Element("name", attributes) and appending them to some root

or

b) fromstring(str) where str is the string representation of those tags in the example

Answer 1

updated test:

from xml.etree.ElementTree import Element, XML, tostring
from timeit import timeit

elist = [e for e in xrange(1000)]

def test_normal():
    eroot = Element('root')
    for e in elist:
        eroot.append(Element("tag", {"attrib" :"%s" %e}))

def test_list():
    eroot = Element('root')
    [eroot.append(Element("tag", {"attrib" :"%s" %e})) for e in elist]


print "etree: %.6f" %timeit(test_normal, number=1000)
print "l-cmp: %.6f" %timeit(test_list, number=1000)

from xml.etree.cElementTree import Element, XML, tostring, fromstring
#from lxml.etree import Element, XML, tostring

print "ctree: %.6f" %timeit(test_normal, number=1000)
print "c-cmp: %.6f" %timeit(test_list, number=1000)

def test_string():
    eroot = "<root>"
    tags = ['<tag attrib="%s" />' %e for e in elist]
    eroot += ' '.join(tags) + '</root>'
    tree = fromstring(eroot)

print "strng: %.6f" %timeit(test_string, number=1000)    


etree: 13.302093
l-cmp: 12.276725
ctree: 5.482961
c-cmp: 5.692758
strng: 6.578780

The cElementTree is the fastest version. So i would say: don’t use the string abomination! 😉