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science scraping with YQL

Posted on: 06 September 2010 in yql, science, scripting, hacking, cool, solo10

Last Saturday at Science Online London I gave a quick tutorial on YQL, and how it might be used to mash up scientific data sets. Below I list some of the sample queries that I was playing with. Before you get started with the console have a look through the documentation. I got a lot of milage out of the part about filters and joins. The blog post by Paul Hogan on using YQL for library maships was also very helpful.

In my presentation I was originally looking at extracing data from a report on soy bean rust spread.

Here are a few sample queries to get you started

1:

select * from html where 
url="http://sbr.ipmpipe.org/cgi-bin/sbr/county_info.cgi?date=2010-07-13&pest=soybean_rust&host=All%20Legumes/Kudzu"

This query just pulls all of the HML from the page. Open in console.

2:

select * from html where 
url="http://sbr.ipmpipe.org/cgi-bin/sbr/county_info.cgi?date=2010-07-13&pest=soybean_rust&host=All%20Legumes/Kudzu" 
and xpath='//table'

This query extracts only the table element from the page. Open in console.

3:

select * from html where 
url="http://sbr.ipmpipe.org/cgi-bin/sbr/county_info.cgi?date=2010-07-13&pest=soybean_rust&host=All%20Legumes/Kudzu" 
and xpath='//table/tr/td[2]'

This query pulls the second item from each row of the table. Open in console.

4:

select * from html where 
url="http://www.mulvany.net/files/ipmsemanticpipe.html" 
and xpath='//table/tr/td[@id="status" and p="Confirmed"]/..'

For this query I copied the table onto my own server and added some basic proto-semantic markup to the column descriptors. I could then call out specific columns from the table. Open in console.

5:

select * from csv WHERE 
url="http://www.mulvany.net/files/ipmpipe.csv" 
and columns='date,place,status'
and status='Confirmed'

With this query I converted the table into a csv file. This demonstrates YQL’s ability to query against csv files. Open in console.

Ian Mulvany

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