此文件（arq.xml）是实验的大型XML文件的一部分：
<!DOCTYPE sysstat PUBLIC "DTD v2.19 sysstat //EN"
"http://pagesperso-orange.fr/sebastien.godard/sysstat-2.19.dtd">
<sysstat>
<sysdata-version>2.19</sysdata-version>
<host nodename="ServerLabDoS">
<sysname>Linux</sysname>
<release>3.16.0-4-686-pae</release>
<machine>i686</machine>
<number-of-cpus>1</number-of-cpus>
<file-date>2017-04-10</file-date>
<file-utc-time>10:39:04</file-utc-time>
<statistics>
<timestamp date="2017-04-10" time="07:50:12" utc="0" interval="119">
<memory per="second" unit="kB">
<memfree>1140168</memfree>
<memused>131440</memused>
<memused-percent>10.34</memused-percent>
<buffers>10928</buffers>
<cached>51716</cached>
<commit>510544</commit>
<commit-percent>28.87</commit-percent>
<active>56880</active>
<inactive>29832</inactive>
<dirty>44</dirty>
</memory>
<network per="second">
<net-dev iface="lo" rxpck="0.00" txpck="0.00" rxkB="0.00" txkB="0.00" rxcmp="0.00" txcmp="0.00" rxmcst="0.00" ifutil-percent="0.00"/>
<net-dev iface="eth0" rxpck="12.58" txpck="11.50" rxkB="11.95" txkB="0.85" rxcmp="0.00" txcmp="0.00" rxmcst="0.00" ifutil-percent="0.00"/>
</network>
</timestamp>
<timestamp date="2017-04-10" time="07:52:01" utc="0" interval="107">
<memory per="second" unit="kB">
<memfree>1140444</memfree>
<memused>131164</memused>
<memused-percent>10.31</memused-percent>
<buffers>11288</buffers>
<cached>51932</cached>
<commit>509260</commit>
<commit-percent>28.80</commit-percent>
<active>57024</active>
<inactive>29840</inactive>
<dirty>28</dirty>
</memory>
<network per="second">
<net-dev iface="lo" rxpck="0.00" txpck="0.00" rxkB="0.00" txkB="0.00" rxcmp="0.00" txcmp="0.00" rxmcst="0.00" ifutil-percent="0.00"/>
<net-dev iface="eth0" rxpck="13.89" txpck="12.69" rxkB="13.71" txkB="0.93" rxcmp="0.00" txcmp="0.00" rxmcst="0.00" ifutil-percent="0.00"/>
</network>
</timestamp>
<timestamp date="2017-04-10" time="07:54:01" utc="0" interval="119">
<memory per="second" unit="kB">
<memfree>1139716</memfree>
<memused>131892</memused>
<memused-percent>10.37</memused-percent>
<buffers>11664</buffers>
<cached>52192</cached>
<commit>509148</commit>
<commit-percent>28.79</commit-percent>
<active>57384</active>
<inactive>29948</inactive>
<dirty>76</dirty>
</memory>
<network per="second">
<net-dev iface="lo" rxpck="0.00" txpck="0.00" rxkB="0.00" txkB="0.00" rxcmp="0.00" txcmp="0.00" rxmcst="0.00" ifutil-percent="0.00"/>
<net-dev iface="eth0" rxpck="13.35" txpck="12.40" rxkB="13.68" txkB="0.91" rxcmp="0.00" txcmp="0.00" rxmcst="0.00" ifutil-percent="0.00"/>
</network>
</timestamp>
</statistics>
</host>
</sysstat>
我的目标是在memused和rxpck
date="2017-04-10" time="07:50:12"和date="2017-04-10" time="07:52:01"
我尝试使用minidom（它的目的是比完整的DOM更简单，也更小）：
from xml.dom import minidom
doc = minidom.parse("arq.xml")
# doc.getElementsByTagName returns NodeList
timestamp = doc.getElementsByTagName("timestamp")[0]
print(timestamp.firstChild.data)
但是没有用。我被卡住了。我只读了一个XML文件。 有人能帮助我吗？如何打印标签？