在python(lxml)中过滤后如何访问kml / xml属性?

阿尔伯特·罗斯曼

我环顾四周,似乎无法找到解决问题的方法。我的基本问题是,我需要找到所有KML元素的名称,这些元素的子多边形包含具有给定纬度/经度的点。

环顾四周,我发现使用keytree,shapely和lxml可以将所有KML元素过滤到所涉及的多边形,然后访问其父级。但是,当我尝试访问父级的属性时,我总是得到一个空列表。我尝试了以下方法:

def __init__(self):
    root=etree.fromstring(open("Example.kml", "r").read())
    kmlns = root.tag.split("}")[0][1:]
    polygons=root.findall(".//{%s}Polygon"%kmlns)
    p = Point(-128.1605,52.474)  #this point exists in one of the polygons
    hits = filter(
        lambda e: shape(keytree.geometry(e)).contains(p),
        polygons)

    print hits
    hit_parent=hits[0].getparent()
    print hit_parent.attrib#this prints {}

通过使用pycharm中的调试器,我能够找到多边形所在的行;据此,hits [0]具有sourceline属性,当我在KML文档中转到该行号时,多边形确实包含该点。向上滚动到多边形的父级,我发现它具有属性(即不是空列表)。我是xml和kml解析的新手;我找错地方了吗?这是kml中的面及其父级:

<Placemark>
            <name>THIS IS THE NAME</name>
            <visibility>0</visibility>
            <styleUrl>#falseColor184010</styleUrl>
            <ExtendedData>
                <SchemaData schemaUrl="#S_AL_TA_BC_2_41_eng_SSSSISSSSSSSSSSSSSSSSSSSSS10">
                    <SimpleData name="ACQTECH">Computed</SimpleData>
                    <SimpleData name="METACOVER">Partial</SimpleData>
                    <SimpleData name="CREDATE">20030416</SimpleData>
                    <SimpleData name="REVDATE">20130504</SimpleData>
                    <SimpleData name="ACCURACY">-1</SimpleData>
                    <SimpleData name="PROVIDER">Federal</SimpleData>
                    <SimpleData name="DATASETNAM">BC</SimpleData>
                    <SimpleData name="SPECVERS">1.1</SimpleData>
                    <SimpleData name="NID">7103157bba3511d892e2080020a0f4c9</SimpleData>
                    <SimpleData name="ALCODE">07876</SimpleData>
                    <SimpleData name="LANGUAGE1">English</SimpleData>
                    <SimpleData name="NAME1">NEEKAS 4</SimpleData>
                    <SimpleData name="LANGUAGE2">French</SimpleData>
                    <SimpleData name="NAME2">NEEKAS NO 4</SimpleData>
                    <SimpleData name="LANGUAGE3">No Language</SimpleData>
                    <SimpleData name="NAME3">NULL</SimpleData>
                    <SimpleData name="LANGUAGE4">No Language</SimpleData>
                    <SimpleData name="NAME4">NULL</SimpleData>
                    <SimpleData name="LANGUAGE5">No Language</SimpleData>
                    <SimpleData name="NAME5">NULL</SimpleData>
                    <SimpleData name="JUR1">BC</SimpleData>
                    <SimpleData name="JUR2"></SimpleData>
                    <SimpleData name="JUR3"></SimpleData>
                    <SimpleData name="JUR4"></SimpleData>
                    <SimpleData name="ALTYPE">Indian Reserve</SimpleData>
                    <SimpleData name="WEBREF">http://clss.nrcan.gc.ca/map-carte/mapbrowser-navigateurcartographique-eng.php?cancode=07876</SimpleData>
                </SchemaData>
            </ExtendedData>
            <Polygon>
                <outerBoundaryIs>
                    <LinearRing>
                        <coordinates>
                            -128.1615722,52.47385589999999,0 -128.1618475,52.47338730000003,0 -128.1623126999999,52.47275560000004,0 -128.1622705,52.47253640000001,0 -128.162017,52.47243320000002,0 -128.1619326,52.4722527,0 -128.1618904,52.4721108,0 -128.161827,52.47202060000003,0 -128.1615523,52.47204629999998,0 -128.1613199,52.47211069999996,0 -128.1607705,52.47205899999999,0 -128.1604538,52.47172369999999,0 -128.1600750999999,52.47149440000001,0 -128.1600821,52.47510580000001,0 -128.1615621,52.47510469999996,0 -128.1615294999999,52.474926,0 -128.1615508,52.47452629999999,0 -128.1615298,52.47416529999997,0 -128.1615722,52.47385589999999,0 
                        </coordinates>
                    </LinearRing>
                </outerBoundaryIs>
            </Polygon>

我想从多边形的父级获得“此名称”。

har07

您的目标文本不是任何元素的属性。给定<Polygon>为context元素,您想转到parent元素<Placemark>,然后获取其child元素<name>这可以使用XPath在一行中完成:

....
print hits
hit_parent = hits[0].find("./../{%s}name"%kmlns)
print hit_parent.text

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