i know this is an R mailing list :) but... i'll recommend you try python
with the beautifulsoup module - makes html processing a cinch.
another thing to note is that wunderground provides very handy RSS feeds
for every location, so rather than parsing the html page (with it's
associated bundles of gunk), you'd have a better time parsing the RSS
feed. (there are some rss parsing libraries for python, too, but in your
simple case it may be simpler to just extract stuff manually with some
well-placed regexps)
so use python to pull that out, and append to a nice tab-delimited file,
and then in your R process just read from that file.
on 06/05/2008 04:45 PM Nutter, Benjamin said the following:
I've tried to tackle a similar question at the request of a coworker.
Unfortunately, it is difficult to read in HTML code because it lacks
character that can consistently be used as a delimiter. The only
guideline I can offer is that any text you're interested in is going to
be between a ">" and a "<". So the goal is to eliminate anything
between < and >.
What's more, if you really want to read in HTML code, you'll need a good
grasp on HTML itself, and some familiarity with how the code you're
reading in is structured. For instance, I'm attaching code that I wrote
to read in HTML tables that were generated by other functions commonly
used in my work place. But my code assumes that the tables are written
by row (using the <tr> tag.
Essentially, after studying the code I was going to read in, I hand
picked the markers that I could use to isolate the text I wanted. I
then proceeded to play a game of Simon Says to break down the code to
smaller and smaller pieces until I got what I wanted.
Unless you're going to be doing this a lot, I wouldn't recommend taking
the time to try and write a function like this. In most cases it's
probably faster just to copy the data by hand. But if you are
determined to make it work, I hope the ideas help.
Benjamin
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of vittorio
Sent: Wednesday, June 04, 2008 3:50 PM
To: [EMAIL PROTECTED]
Subject: [Possible SPAM] [R] Reading selected lines in an .html file
Dear friend,
In an R program running permanently on a server I would like to read
hour by
hour the temperature in *C and the humidity from a site like this
(actually,
from many of such sites):
http://www.wunderground.com/global/stations/16239.html
How can I read the content of the site and select the info I need?
Ciao
Vittorio
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