我正在尝试从返回带有NULL NODES的XML文件的API中获取数据，我需要那些知道丢失数据的地方。请参见下面的XML，节点CHUVA07至CHUVA11。
<?xml version="1.0" encoding="UTF-8"?>
<DataTable xmlns="http://MRCS/">
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" id="NewDataSet">...</xs:schema>
<diffgr:diffgram xmlns:diffgr="urn:schemas-microsoft-com:xml-diffgram-v1" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
<DocumentElement xmlns="">
<SerieHistorica diffgr:id="SerieHistorica1" msdata:rowOrder="0">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica2" msdata:rowOrder="1">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica3" msdata:rowOrder="2">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica4" msdata:rowOrder="3">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica5" msdata:rowOrder="4">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica6" msdata:rowOrder="5">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica7" msdata:rowOrder="6">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica8" msdata:rowOrder="7">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica9" msdata:rowOrder="8">...</SerieHistorica>
<SerieHistorica diffgr:id="SerieHistorica10" msdata:rowOrder="9">
<EstacaoCodigo>1943022</EstacaoCodigo>
<NivelConsistencia>1</NivelConsistencia>
<DataHora>2015-03-01 00:00:00</DataHora>
<TipoMedicaoChuvas>1</TipoMedicaoChuvas>
<Maxima>44.8</Maxima>
<Total>134.9</Total>
<DiaMaxima>24</DiaMaxima>
<NumDiasDeChuva />
<MaximaStatus>1</MaximaStatus>
<TotalStatus>1</TotalStatus>
<NumDiasDeChuvaStatus>0</NumDiasDeChuvaStatus>
<TotalAnual />
<TotalAnualStatus>0</TotalAnualStatus>
<Chuva01>2.6</Chuva01>
<Chuva02>0.5</Chuva02>
<Chuva03>0</Chuva03>
<Chuva04>0</Chuva04>
<Chuva05>0</Chuva05>
<Chuva06>18.5</Chuva06>
<Chuva07 />
<Chuva08 />
<Chuva09 />
<Chuva10 />
<Chuva11 />
<Chuva12>29.7</Chuva12>
<Chuva13>0</Chuva13>
<Chuva14>1.8</Chuva14>
<Chuva15>0</Chuva15>
<Chuva16>0</Chuva16>
<Chuva17>0</Chuva17>
<Chuva18>0</Chuva18>
<Chuva19>0</Chuva19>
<Chuva20>0</Chuva20>
<Chuva21>14.8</Chuva21>
<Chuva22>1</Chuva22>
<Chuva23>5.7</Chuva23>
<Chuva24>44.8</Chuva24>
<Chuva25>1.1</Chuva25>
<Chuva26>0</Chuva26>
<Chuva27>0</Chuva27>
<Chuva28>0</Chuva28>
<Chuva29>0</Chuva29>
<Chuva30>0</Chuva30>
<Chuva31>14.4</Chuva31>
<Chuva01Status>1</Chuva01Status>
<Chuva02Status>1</Chuva02Status>
<Chuva03Status>1</Chuva03Status>
<Chuva04Status>1</Chuva04Status>
<Chuva05Status>1</Chuva05Status>
<Chuva06Status>1</Chuva06Status>
<Chuva07Status>0</Chuva07Status>
<Chuva08Status>0</Chuva08Status>
<Chuva09Status>0</Chuva09Status>
<Chuva10Status>0</Chuva10Status>
<Chuva11Status>0</Chuva11Status>
<Chuva12Status>4</Chuva12Status>
<Chuva13Status>1</Chuva13Status>
<Chuva14Status>1</Chuva14Status>
<Chuva15Status>1</Chuva15Status>
<Chuva16Status>1</Chuva16Status>
<Chuva17Status>1</Chuva17Status>
<Chuva18Status>1</Chuva18Status>
<Chuva19Status>1</Chuva19Status>
<Chuva20Status>1</Chuva20Status>
<Chuva21Status>1</Chuva21Status>
<Chuva22Status>1</Chuva22Status>
<Chuva23Status>1</Chuva23Status>
<Chuva24Status>1</Chuva24Status>
<Chuva25Status>1</Chuva25Status>
<Chuva26Status>1</Chuva26Status>
<Chuva27Status>1</Chuva27Status>
<Chuva28Status>1</Chuva28Status>
<Chuva29Status>1</Chuva29Status>
<Chuva30Status>1</Chuva30Status>
<Chuva31Status>1</Chuva31Status>
<DataIns>2015-08-04 00:00:00</DataIns>
</SerieHistorica>
</DocumentElement>
</diffgr:diffgram>
</DataTable>
我正在使用的代码：
xml.doc = content(xml)
##Extract data from list object
xml.list <- xml2::as_list(xml.doc)
xml.data <- xml.list$DataTable$diffgram$`DocumentElement`
station.data <- matrix(ncol=length(xml.data),nrow = 31)
if (length(is.na(station.data))==31) {
next
print("Skipping this iteration")
} #if no data for this station go onto next iteration
for (j in 1:length(xml.data)) { #j for each record, rows 1:LOD
month <- xml.data[[j]]
df <- as.data.frame(unlist(month[14:44]))
if(length(df)==0) next
station.data[1:length(df[,1]),j] <- as.numeric(as.character(df[,1]))
}
上面的代码返回错误位置的NA。应该在7到11之间，并且在27到31之间。
Day Month1 Month2 Month3
1 2.6 0.0 0.0
2 0.5 0.0 39.2
3 0.0 0.0 0.0
4 0.0 14.8 4.0
5 0.0 17.6 0.0
6 18.5 38.6 0.0
7 29.7 9.8 0.0
8 0.0 26.2 0.0
9 1.8 29.6 0.0
10 0.0 13.0 0.0
11 0.0 0.0 0.0
12 0.0 0.0 0.0
13 0.0 0.0 0.0
14 0.0 0.0 0.0
15 0.0 0.0 0.0
16 14.8 12.9 0.0
17 1.0 0.0 0.0
18 5.7 14.8 0.0
19 44.8 0.0 0.0
20 1.1 0.0 0.0
21 0.0 0.0 0.0
22 0.0 0.0 0.5
23 0.0 0.0 0.0
24 0.0 0.0 4.3
25 0.0 0.0 15.1
26 14.4 14.0 47.6
27 NA 1.8 7.8
28 NA 11.4 2.0
29 NA NA 2.2
30 NA NA 0.0
31 NA NA 0.0
有什么线索可以解决这个问题吗？