我有一个看起来像这样的数据框：
col 1 col 2
["item - 1", "item - 2"] ["item - 3", "item - 4"]
如何从此数据框中提取项目，以便最终获得列标题和列1和列2在每一行中出现的次数
col 1 col 2 item1 item2 item3 item4
["item - 1", "item - 2"] ["item - 3"] 1 1 1 0
["item - 1"] ["item - 3", "item - 4"] 1 0 1 1
["item - 1", "item - 2"] ["item - 3", "item - 4"] 1 1 1 1
我尝试了多种方法，但每次遇到错误：不可哈希类型：“列表”
答案 0 :(得分：0)
使用public App() {
super();
try {
test( testDoc1() );
test( testDoc2() );
} catch( Exception e ) {
e.printStackTrace();
} finally {
Log.d( "TEST-FINISHED", "test is finished" );
}
}
private String toXmlString(Document document) throws TransformerException {
DOMSource domSource = new DOMSource(document);
StringWriter writer = new StringWriter();
StreamResult result = new StreamResult(writer);
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.transform(domSource, result);
return writer.toString();
}
private Document testDoc1() throws ParserConfigurationException {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
Document mDocument = documentBuilderFactory.newDocumentBuilder().newDocument();
String XMLNS_NAMESPACE_URI = "http://www.w3.org/2000/xmlns/";
//Element mKmlElement = mDocument.createElement("kml");
Element mKmlElement = mDocument.createElementNS("http://www.opengis.net/kml/2.2", "kml");
//mKmlElement.setAttributeNS(XMLNS_NAMESPACE_URI, "xmlns", "http://www.opengis.net/kml/2.2");
mKmlElement.setAttributeNS(XMLNS_NAMESPACE_URI, "xmlns:gx", "http://www.google.com/kml/ext/2.2");
mDocument.appendChild(mKmlElement);
//Element mPlacemarkElement = mDocument.createElement("Placemark");
Element mPlacemarkElement = mDocument.createElementNS("http://www.opengis.net/kml/2.2", "Placemark");
//mPlacemarkElement.setAttributeNS(XMLNS_NAMESPACE_URI, "xmlns", "http://www.opengis.net/kml/2.2");
mKmlElement.appendChild(mPlacemarkElement);
//Element gxTrackElement = mDocument.createElement("gx:Track");
Element gxTrackElement = mDocument.createElementNS("http://www.google.com/kml/ext/2.2","gx:Track");
mPlacemarkElement.appendChild(gxTrackElement);
//Element gxCoordElement = mDocument.createElement("gx:coord");
Element gxCoordElement = mDocument.createElementNS("http://www.google.com/kml/ext/2.2", "gx:coord");
gxCoordElement.setTextContent("-122.207881 37.371915 156.000000");
gxTrackElement.appendChild(gxCoordElement);
return mDocument;
}
private Document testDoc2() throws ParserConfigurationException, IOException, SAXException {
String kmlString = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><kml xmlns=\"http://www.opengis.net/kml/2.2\" xmlns:gx=\"http://www.google.com/kml/ext/2.2\"><Placemark><gx:Track><gx:coord>-122.207881 37.371915 156.000000</gx:coord></gx:Track></Placemark></kml>";
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
Document mDocument = documentBuilderFactory.newDocumentBuilder().parse(new
InputSource(new StringReader(kmlString)));
return mDocument;
}
private void test(Document mDocument) throws Exception {
String xml = toXmlString(mDocument);
System.out.println( xml);
XPath xPath = XPathFactory.newInstance().newXPath();
xPath.setNamespaceContext(new NamespaceContext() {
@Override
public String getNamespaceURI(String prefix) {
return "gx".equals(prefix) ? "http://www.google.com/kml/ext/2.2" : "http://www.opengis.net/kml/2.2";
}
@Override
public String getPrefix(String namespaceURI) {
if ("http://www.google.com/kml/ext/2.2".equals(namespaceURI)) {
return "gx";
}
return null;
}
@Override
public Iterator getPrefixes(String namespaceURI) {
List<String> ns = new ArrayList<>();
ns.add("gx");
return ns.iterator();
}
});
NodeList result1 = (NodeList) xPath.evaluate("/k:kml", mDocument, XPathConstants.NODESET);
System.out.println(String.valueOf(result1.getLength()));
System.out.println("Namespace URI: " + result1.item(0).getNamespaceURI());
System.out.println("Prefix: " + result1.item(0).getPrefix());
NodeList result2 = (NodeList) xPath.evaluate("/k:kml/k:Placemark", mDocument, XPathConstants.NODESET);
System.out.println( String.valueOf(result2.getLength()));
NodeList result3 = (NodeList) xPath.evaluate("/k:kml/k:Placemark/gx:Track", mDocument, XPathConstants.NODESET);
System.out.println(String.valueOf(result3.getLength()));
}
中的列表和字符串从来没有效率。但是您仍然可以使用它们。
使用sklearn.preprocessing.MultiLabelBinarizer
pandas使用纯熊猫方法也可以，但是很慢。
mlb = MultiLabelBinarizer()
pd.DataFrame(mlb.fit_transform(ds['col 1'].add(ds['col 2'])),
columns=mlb.classes_,
index=df.index)
item - 1 item - 2 item - 3 item - 4
0 1 1 1 0
1 1 0 1 1