[R] How to find b entries using xPath?

[Duncan Temple Lang]

guox at ucalgary.ca wrote:
> We got all rows by:
> 
> library(XML)
> doc =
> htmlParse('http://www.statcan.gc.ca/daily-quotidien/090520/t090520b1-eng.htm')
> rows = xpathSApply(doc, '//table/tbody/tr')
> 
> The last row is:
> 
> row_last = rows[15]
> row_last
> 
> [[1]]
> <tr><td id="t1stub17" class="stub1 RGBShade"><b>Unsmoothed composite
> leading indicator</b></td>
> <td align="right" headers="hdt1r1c2 t1stub17"
> class="data"><b>221.8</b></td>
> <td align="right" headers="hdt1r1c3 t1stub17"
> class="data"><b>218.4</b></td>
> <td align="right" headers="hdt1r1c4 t1stub17"
> class="data"><b>217.1</b></td>
> <td align="right" headers="hdt1r1c5 t1stub17"
> class="data"><b>211.2</b></td>
> <td align="right" headers="hdt1r1c6 t1stub17"
> class="data"><b>209.4</b></td>
> <td align="right" headers="hdt1r1c7 t1stub17"
> class="data"><b>210.5</b></td>
> <td align="right" headers="hdt1r1c8 t1stub17"
> class="data"><b>0.5</b></td>
> </tr>
> 
> How to find these b entries: Unsmoothed composite leading indicator,
> 221.8, 218.4, 217.1, 211.2, 209.4, 210.5, 0.5?

Use XPath again and restrict the search for the <b> nodes to
this 15-th row

  as.numeric(xpathSApply( row_last, ".//b", xmlValue))

Note the . at the beginning of the XPath expression
which anchors the search at the <tr> in row_last.

  D.


> Thanks,
> 
> -james
> 
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