Question

我正在尝试使用XML包读取tcx文件（来自自行车教练）。这个问题Import TCX into R using XML package让我开始了。在2011年的例子中，数据看起来像这样：

react

阅读本文的代码很简单：

<?xml version="1.0" encoding="UTF-8"?>
<TrainingCenterDatabase xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2">
<Activities>
    <Activity Sport="Running">
        <Id>2011-10-30T16:05:48Z</Id>
        <Lap StartTime="2011-10-30T16:05:48Z">
            <TotalTimeSeconds>3855.99</TotalTimeSeconds>
            <DistanceMeters>12498.8115</DistanceMeters>
            <MaximumSpeed>4.45662498</MaximumSpeed>
            <Calories>1011</Calories>
            <Intensity>Active</Intensity>
            <TriggerMethod>Manual</TriggerMethod>
            <Track>
                <Trackpoint>
                    <Time>2011-10-30T16:05:48Z</Time>
                    <Position>
                        <LatitudeDegrees>52.33613318</LatitudeDegrees>
                        <LongitudeDegrees>-1.58814317</LongitudeDegrees>
                    </Position>
                    <AltitudeMeters>77.5234375</AltitudeMeters>
                    <DistanceMeters>0.00000000</DistanceMeters>
                </Trackpoint>
                <Trackpoint>
                    <Time>2011-10-30T16:05:49Z</Time>
                    <Position>
                        <LatitudeDegrees>52.33614810</LatitudeDegrees>
                        <LongitudeDegrees>-1.58814283</LongitudeDegrees>
                    </Position>
                    <AltitudeMeters>77.5234375</AltitudeMeters>
                    <DistanceMeters>1.77584004</DistanceMeters>
                </Trackpoint>
...

我有一个更复杂的tcx文件：

library(XML)
doc = xmlParse("testfile.tcx")
basic = xmlToDataFrame(nodes <- getNodeSet(doc, "//ns:Trackpoint", "ns"))

（中间省略了许多行）

我对每个Trackpoint感兴趣。也就是说，我不关心最后一个Trackpoint之后出现的扩展，但我做想要记录每个Trackpoint中记录的扩展（Watts and Speed）。

使用上面建议的代码生成以下内容：

<?xml version="1.0" encoding="utf-8"?>
<TrainingCenterDatabase xsi:schemaLocation="http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2 http://www.garmin.com/xmlschemas/TrainingCenterDatabasev2.xsd" xmlns:ns5="http://www.garmin.com/xmlschemas/ActivityGoals/v1" xmlns:ns3="http://www.garmin.com/xmlschemas/ActivityExtension/v2" xmlns:ns2="http://www.garmin.com/xmlschemas/UserProfile/v2" xmlns="http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns4="http://www.garmin.com/xmlschemas/ProfileExtension/v1" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Activities xmlns="http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2">
    <Activity Sport="Biking">
      <Id>2017-01-21T17:33:40.86Z</Id>
      <Lap StartTime="2017-01-21T17:33:40Z">
        <TotalTimeSeconds>720</TotalTimeSeconds>
        <DistanceMeters>3565.9106917557524</DistanceMeters>
        <MaximumSpeed>5.39404950335725</MaximumSpeed>
        <Calories>68</Calories>
        <AverageHeartRateBpm>
          <Value>123</Value>
        </AverageHeartRateBpm>
        <MaximumHeartRateBpm>
          <Value>128</Value>
        </MaximumHeartRateBpm>
        <Intensity>Active</Intensity>
        <Cadence>75</Cadence>
        <TriggerMethod>Time</TriggerMethod>
        <Track>
          <Trackpoint>
            <Time>2017-01-21T17:33:40Z</Time>
            <DistanceMeters>4.68</DistanceMeters>
            <Cadence>79</Cadence>
            <Extensions>
              <ns3:TPX>
                <ns3:Watts>87</ns3:Watts>
                <ns3:Speed>4.68072232948508</ns3:Speed>
              </ns3:TPX>
            </Extensions>
          </Trackpoint>
          <Trackpoint>
            <Time>2017-01-21T17:33:41Z</Time>
            <DistanceMeters>9.41</DistanceMeters>
            <Cadence>81</Cadence>
            <Extensions>
              <ns3:TPX>
                <ns3:Watts>88</ns3:Watts>
                <ns3:Speed>4.726922499738</ns3:Speed>
              </ns3:TPX>
            </Extensions>
          </Trackpoint>
        </Track>
        <Extensions>
          <ns3:LX>
            <AvgSpeed xmlns:ns3="http://www.garmin.com/xmlschemas/ActivityExtension/v2" xmlns="">4.45096542560575</AvgSpeed>
          </ns3:LX>
          <ns3:LX>
            <ns3:MaxBikeCadence>111</ns3:MaxBikeCadence>
          </ns3:LX>
          <ns3:LX>
            <ns3:MaxWatts>161</ns3:MaxWatts>
          </ns3:LX>
          <ns3:LX>
            <ns3:AvgWatts>81</ns3:AvgWatts>
          </ns3:LX>
        </Extensions>
      </Lap>
    </Activity>
  </Activities>
</TrainingCenterDatabase>

意味着扩展名被提取，但是连接在一起并且它们的名称丢失了。

IOW，我想要一个如下所示的数据框：

> head(basic,2)
                  Time DistanceMeters Cadence         Extensions HeartRateBpm
1 2017-01-21T17:33:40Z           4.68      79 874.68072232948508         <NA>
2 2017-01-21T17:33:41Z           9.41      81   884.726922499738         <NA>

我尝试过使用XPath语法和命名空间的各种问题，但我最接近的是

> head(basic,2)
                  Time DistanceMeters Cadence         Watts    Speed HeartRateBpm
1 2017-01-21T17:33:40Z           4.68      79       87     4.68072232948508         <NA>
2 2017-01-21T17:33:41Z           9.41      81       88     4.726922499738         <NA>

当然没有任何进步。

有人可以帮忙吗？

Answer 1

由于TPX有子节点，xmlToDataFrame会将它们混合在一起。尝试将xmlToList转换为data.frame

nodes <- getNodeSet(doc, "//ns:Trackpoint", "ns")
rows <-  lapply(nodes, function(x) data.frame(xmlToList(x) )) 
do.call("rbind", rows)
                  Time DistanceMeters Cadence Extensions.TPX.Watts Extensions.TPX.Speed
1 2017-01-21T17:33:40Z           4.68      79                   87     4.68072232948508
2 2017-01-21T17:33:41Z           9.41      81                   88       4.726922499738

Answer 2

这是一种丑陋的方式，使用xmltoDataFrame执行两次，基于Transforming data from xml into R dataframe，由https://stackoverflow.com/users/516548/g-grothendieck指出（并由其提供）

doc = xmlParse("file.tcx")

# get the stuff in the Trackpoint main node
basic = xmlToDataFrame(nodes <- getNodeSet(doc, "//ns:Trackpoint", "ns"))

# get the watts and speed
extra = do.call("rbind", xpathApply(doc, "//ns3:TPX", function(N) {
   data.frame(
         Watts = xmlValue(N[["Watts"]]),
         Speed = xmlValue(N[["Speed"]])
         )
    }))

# paste them together
ride = cbind(basic[,-4], extra)

> ride
                  Time DistanceMeters Cadence Watts            Speed
1 2017-01-21T17:33:40Z           4.68      79    87 4.68072232948508
2 2017-01-21T17:33:41Z           9.41      81    88   4.726922499738

再次感谢，所有人。

使用R中的XML包读取复杂（tcx）文件

2 个答案: