使用样式属性Ruby使用Nokogiri刮擦表数据

Question

I want to scrape the text value of the td s in this webpage ex: 0.2197 British Pound

<table border=1 cellpadding=5 cellspacing=0 style="font-weight: normal; font-size: 10.5;"><tr><td width=50>1791</td><td>0.2195 British Pound</td></tr><tr><td width=50>1792</td><td>0.2239 British Pound</td></tr><tr><td width=50>1793</td><td>0.2218 British Pound</td></tr><tr><td width=50>1794</td><td>0.2106 British Pound</td></tr><tr><td width=50>1795</td><td>0.2209 British Pound</td></tr><tr><td width=50>1796</td><td>0.2333 British Pound</td></tr><tr><td width=50>1797</td><td>0.2254 British Pound</td></tr><tr><td width=50>1798</td><td>0.2279 British Pound</td></tr><tr><td width=50>1799</td><td>0.2420 British Pound</td></tr><tr><td width=50>1800</td><td>0.2199 British Pound</td></tr><tr><td width=50>1801</td><td>0.2283 British Pound</td></tr><tr><td width=50>1802</td><td>0.2230 British Pound</td></tr><tr><td width=50>1803</td><td>0.2202 British Pound</td></tr><tr><td width=50>1804</td><td>0.2197 British Pound</td></tr><tr><td width=50>1805</td><td>0.2300 British Pound</td></tr>

However, the webpage I am scraping has several table so I need a way to specify this particular table.

This is what I've tried:

exchange_rate_table = Nokogiri::HTML(open('http://measuringworth.com/datasets/exchangeglobal/result.php?year_source=1791&year_result=2007&countryE%5B%5D=United+Kingdom'))
        exchange_rate_table.css('td')

but that returns all of the td s, some that are even outside this table.

Answer 1

In your solution you found all <td> elements:

Here, you opened the entire web page:

exchange_rate_table = Nokogiri::HTML(open('http://measuringworth.com/datasets/exchangeglobal/result.php?year_source=1791&year_result=2007&countryE%5B%5D=United+Kingdom'))

Here, you found all <td> elements in the web page (if that's what you want):

exchange_rate_table.css('td')

There are two tables in the web page, one of which you'd like to exclude. In this particular page you only have two <table> elements.

Instead of finding all <td> elements, you should find one table, and then its <td> elements.

Find the web page:

web_page = Nokogiri::HTML(open('http://measuringworth.com/datasets/exchangeglobal/result.php?year_source=1791&year_result=2007&countryE%5B%5D=United+Kingdom'))

Find the second table (the one with the exchange rates):

exchange_rate_table = web_page.css('table').last

Find all of the <td> elements in that table table:

exchange_rate_cells = exchange_rate_table.css('td')