Htykuut

I want to read a table directly from a webpage with R. In reader's view the webpage with the table looks like this:

I used two packages to read the table from the webpage. It worked OK except the fact that the table is read as a list.

library(RCurl)

library(XML)

d<-getURL('https://securewordpresswebsiteAddress/data/')

d<-readHTMLTable(d, header=T)

Here is what I get after reading the table

> d

$`NULL`

    ID      X       Y Depth    P

1 1046 256857 2632323    13  2.8

2 1054 257090 2632039    13  1.1

3 1057 257099 2631981    13  2.6

4 1058 257071 2632004     9  2.1

5 1060 257173 2632004    13    4

6 1089 257194 2631660    13 14.1

Where is this $NULL coming from? is there a way to avoid it?

Your code is actually returning a list of named elements, based on the makeup of your HTML table.

> readHTMLTable('~/htmltest.html', header=TRUE, as.data.frame=FALSE)

$`NULL`

$`NULL`$`ID`

[1] "1046" "1054" "1057" "1058" "1060" "1089"



$`NULL`$X

[1] "256857" "257090" "257099" "257071" "257194" "257194"



$`NULL`$Y

[1] "2632323" "2632039" "2631981" "2632004" "2632004" "2631660"



$`NULL`$Depth

[1] "13" "13" "13" "9"  "13" "13"



$`NULL`$P

[1] "2.8"  "1.1"  "2.6"  "2.1"  "4"    "14.1"

So when you use as.data.frame = TRUE it coerces this list of elements into another list containing a data.frame. Since the HTML table does not have an id associated to it, it is named NULL.

Fix this by adding an id inside the table tag when you write your HTML table, like so <table id='sometable'> .. </table>

> readHTMLTable('~/htmltest.html', header=TRUE, as.data.frame=TRUE)



$`sometable`

    ID      X       Y Depth    P

1 1046 256857 2632323    13  2.8

2 1054 257090 2632039    13  1.1

3 1057 257099 2631981    13  2.6

4 1058 257071 2632004     9  2.1

5 1060 257194 2632004    13    4

6 1089 257194 2631660    13 14.1

The HTML file I am reading contains the following table:

<table id='sometable'>

    <thead>

        <tr><th>ID</th><th>X</th><th>Y</th><th>Depth</th><th>P</th></tr>

    </thead>

    <tbody>

        <tr><td>1046</td><td>256857</td><td>2632323</td><td>13</td><td>2.8</td></tr>

        <tr><td>1054</td><td>257090</td><td>2632039</td><td>13</td><td>1.1</td></tr>

        <tr><td>1057</td><td>257099</td><td>2631981</td><td>13</td><td>2.6</td></tr>

        <tr><td>1058</td><td>257071</td><td>2632004</td><td>9</td><td>2.1</td></tr>

        <tr><td>1060</td><td>257194</td><td>2632004</td><td>13</td><td>4</td></tr>

        <tr><td>1089</td><td>257194</td><td>2631660</td><td>13</td><td>14.1</td></tr>

    </tbody>

</table>