将xml转换为没有NA的数据帧

Question

我有一个xml文件的问题。我无法从这些xml结构中获得正确的数据帧。

<Node1 Value1="start">        
    <Node2 Value2="1110" Value3="345">    
     <Node3 Value4="500" Value5="3">    
      <Node4 Value6="484663" Value7="130" /> 
      <Node4 Value6="253234" Value7="59" /> 
      <Node4 Value6="198476" Value7="131" /> 
     </Node3>          
     <Node3 Value4="113" Value5="1">    
      <Node4 Value6="2009343" Value7="555" /> 
      <Node4 Value6="2530931" Value7="333" /> 
      <Node4 Value6="1984761" Value7="111" /> 
     </Node3>          
    </Node2>           
</Node1> 

我用下面几行来获取数据帧。但是有很多NA。我如何强制data.table重复值，而不是将NA放入？

library(data.table)                  
library(XML)                    
# test.xml = the xml-file 

test <- xmlTreeParse("test.xml", useInternalNodes=TRUE)         

Node1 <- rbindlist(lapply(test["//*"], function(x)as.list(xmlAttrs(x))), fill = TRUE, use.names = TRUE) 

结果应该是这样..

Value1 Value2 Value3 Value4 Value5 Value6 Value7 
start 1110 345 500 3  484663 130 
start 1110 345 500 3  253234 59 
start 1110 345 500 3  198476 131 
start 1110 345 113 1  2009343 555 
start 1110 345 113 1  2530931 333 
start 1110 345 113 1  1984761 111 

Answer 1

b1 <- t(xpathSApply(doc, "//Node4", xmlAncestors, xmlAttrs)) 
b1 <- data.frame(matrix(unlist(b1), 
          nrow = nrow(b1), 
          ncol = ncol(b1), 
          dimnames = list(NULL, colnames(b1))), 
        stringsAsFactors = FALSE) 
b1 
# Value1 Value2 Value3 Value4 Value5 Value6 Value7 
# 1 start 1110 345 500  3 484663 130 
# 2 start 1110 345 500  3 253234  59 
# 3 start 1110 345 500  3 198476 131 
# 4 start 1110 345 113  1 2009343 555 
# 5 start 1110 345 113  1 2530931 333 
# 6 start 1110 345 113  1 1984761 111 

数据：

library(XML) 
    doc <- xmlParse('<Node1 Value1="start">        
     <Node2 Value2="1110" Value3="345">    
        <Node3 Value4="500" Value5="3">    
        <Node4 Value6="484663" Value7="130" /> 
        <Node4 Value6="253234" Value7="59" /> 
        <Node4 Value6="198476" Value7="131" /> 
        </Node3>          
        <Node3 Value4="113" Value5="1">    
        <Node4 Value6="2009343" Value7="555" /> 
        <Node4 Value6="2530931" Value7="333" /> 
        <Node4 Value6="1984761" Value7="111" /> 
        </Node3>          
        </Node2>           
        </Node1>') 

Answer 2

使用fill从tidyr包

XML:::xmlAttrsToDataFrame(doc["//*"]) %>% fill(1:6) %>% filter(!is.na(Value7)) 
    Value1 Value2 Value3 Value4 Value5 Value6 Value7 
1 start 1110 345 500  3 484663 130 
2 start 1110 345 500  3 253234  59 
3 start 1110 345 500  3 198476 131 
4 start 1110 345 113  1 2009343 555 
5 start 1110 345 113  1 2530931 333 
6 start 1110 345 113  1 1984761 111