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POPython-Regex-Distinguish and use repeated pattern in a string
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  1. POPython-Regex-Distinguish and use repeated pattern in a string
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    copied!<p><strong>Edit:</strong> so I came to realize, with the kind help from answers below, that parsing html with regex is generally a bad idea. For what it's worth, if someone else comes across my post someday with the same question, here's a link to two similar questions on this topic, with a far greater deal of debate and explanation that you might find useful: <a href="https://stackoverflow.com/questions/590747/using-regular-expressions-to-parse-html-why-not">Using regular expressions to parse HTML: why not?</a> and this one: <a href="https://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454">RegEx match open tags except XHTML self-contained tags</a> </p> <p><strong>Specs:</strong> Python 3.3.1</p> <p><strong>What I was trying to do:</strong> I was writing a web page extractor to grab the weather data from a website, which for my project has 3 meaningful sections: temperature "Right Now", "Earlier Today" and "Tonight". I intend to grab these 3 numbers only and leave out all other text. In the code below I used the presence of specific html elements preceding the temperature number as pattern to help me grab the number itself. </p> <p>All the data I need is in this block of html code excerpt: (namely <code>89</code>,<code>96</code> and <code>80</code>)</p> <pre><code>&lt;div class="wx-timepart-title"&gt; Earlier Today &lt;/div&gt; &lt;div class="wx-timepart-title"&gt;Tonight&lt;/div&gt; &lt;div class="wx-data-part wx-first"&gt; &lt;img src="http://s.imwx.com/v.20120328.084208/img/wxicon/120/29.png" height="120" width="120" alt="Partly Cloudy" class="wx-weather-icon"&gt; &lt;/div&gt; &lt;div class="wx-data-part"&gt; &lt;img src="http://s.imwx.com/v.20120328.084208/img/wxicon/120/30.png" height="120" width="120" alt="Partly Cloudy" class="wx-weather-icon"&gt; &lt;/div&gt; &lt;div class="wx-data-part"&gt; &lt;img src="http://s.imwx.com/v.20120328.084208/img/wxicon/120/29.png" height="120" width="120" alt="Partly Cloudy" class="wx-weather-icon"&gt; &lt;/div&gt; &lt;div class="wx-data-part wx-first"&gt; &lt;div class="wx-temperature"&gt;&lt;span itemprop="temperature-fahrenheit"&gt;89&lt;/span&gt;&lt;span class="wx-degrees"&gt;&amp;deg;&lt;span class="wx-unit"&gt;F&lt;/span&gt;&lt;/span&gt;&lt;/div&gt; &lt;div class="wx-temperature-label"&gt;FEELS LIKE &lt;span itemprop="feels-like-temperature-fahrenheit"&gt;94&lt;/span&gt;&amp;deg;&lt;/div&gt; &lt;/div&gt; &lt;div class="wx-data-part"&gt; &lt;div class="wx-temperature"&gt;96&lt;span class="wx-degrees"&gt;&amp;deg;&lt;/span&gt;&lt;/div&gt; &lt;div class="wx-temperature-label"&gt;HIGH AT 4:45 PM&lt;/div&gt; &lt;/div&gt; &lt;div class="wx-data-part"&gt; &lt;div class="wx-temperature"&gt;80&lt;span class="wx-degrees"&gt;&amp;deg;&lt;/span&gt;&lt;/div&gt; &lt;div class="wx-temperature-label"&gt;LOW&lt;/div&gt; &lt;/div&gt; </code></pre> <p><strong>The solution I came up with:</strong> </p> <pre><code>import urllib.request import re # open the webpage and read the html code into a string; base = urllib.request.urlopen('http://www.weather.com/weather/today/Washington+DC+USDC0001:1:US') f = base.readlines() f = str(f) # temperature "Right Now" match1 = re.search(r'&lt;div class="wx-temperature"&gt;&lt;span itemprop="temperature-fahrenheit"&gt;\w\w',f) if match1: result1 = match1.group() right_now = result1[68:] print(right_now) # temperature "Earlier Today" match2 = re.search(r'&lt;div class="wx-temperature"&gt;\w\w',f) if match2: result2 = match2.group() ealier_today = result2[28:] print(ealier_today) # temperature "Tonight" match3 = re.search(r'&lt;div class="wx-temperature"&gt;\w\w',f) if match3: result3 = match3.group() tonight = result3[28:] print(tonight) </code></pre> <p>The three print statements are just for testing if data was grabbed correctly. </p> <p><strong>My question:</strong> problem occurred when it came to the third regex(<code>match3</code>), displaying the temperature for <code>match2</code>. I figure it's because it uses the same regex pattern as the second? So I guess my question is that how do you search for multiple results with the same regex pattern. Or is it that you can only grab the first occurrence of a pattern? I'm quite new to Python and it's my first few days into regular expression. I appreciate it if you could share some general pointers about my solution, or about my general line of thinking towards this project. Thank you! </p>
 

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