[Tut] Python One Line Regex Match

[Tut] Python One Line Regex Match - Printable Version

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[Tut] Python One Line Regex Match - xSicKxBot - 08-12-2020

Python One Line Regex Match

<div>Summary: To match a <code>pattern</code> in a given <code>text</code> using only a single line of Python code, use the one-liner <code>import re; print(re.findall(pattern, text))</code> that imports the regular expression library re and prints the result of the <code>findall()</code> function to the shell.
Problem: Given a string and a regular expression pattern. Match the string for the regex pattern—in a single line of Python code!
Example: Consider the following example that matches the pattern <code>'F.*r'</code> against the string <code>'Learn Python with Finxter'</code>.
<pre class="EnlighterJSRAW" data-enlighter-language="generic" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group="">import re
s = 'Learn Python with Finxter'
p = 'F.*r'
# Found Match of p in s: 'Finxter'</pre>
Let’s dive into the different ways of writing this into a single line of Python code!
 <iframe height="600px" width="100%" src="https://repl.it/@finxter/BriskAcidicWatch?lite=true" scrolling="no" frameborder="no" allowtransparency="true" allowfullscreen="true" sandbox="allow-forms allow-pointer-lock allow-popups allow-same-origin allow-scripts allow-modals"></iframe> 
Exercise: Run the code. What’s the output of each method? Why does the output differ?
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<h2>Method 1: findall()</h2>
The re.findall(pattern, string, flags=0) method returns a list of string matches. Read more in <a href="https://blog.finxter.com/python-re-findall/">our blog tutorial</a>.
<pre class="EnlighterJSRAW" data-enlighter-language="generic" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group=""># Method 1: findall()
import re; print(re.findall('F.*r', 'Learn Python with Finxter'))
# ['Finxter']</pre>
There’s no better way of importing the <code><a href="https://blog.finxter.com/python-regex/" title="Python Regex Superpower [Full Tutorial]">re</a></code> library and calling the <code>re.findall()</code> function in a single line of code—you must use the semicolon <code>A;B</code> to separate the statements <code>A</code> and <code>B</code>. 
The <code>findall()</code> function finds all occurrences of the pattern in the string. 
<h2>Method 2: search()</h2>
The re.search(pattern, string, flags=0) method returns a match object of the first match. Read more in <a href="https://blog.finxter.com/python-regex-search/">our blog tutorial</a>.
<pre class="EnlighterJSRAW" data-enlighter-language="generic" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group=""># Method 2: search()
import re; print(re.search('F.*r', 'Learn Python with Finxter'))
# <re.Match object; span=(18, 25), match='Finxter'></pre>
The <code>search()</code> function finds the first match of the pattern in the string and returns a matching object
<h2>Method 3: match()</h2>
The re.match(pattern, string, flags=0) method returns a match object if the regex matches at the beginning of the string. Read more in <a href="https://blog.finxter.com/python-regex-match/">our blog tutorial</a>.
<pre class="EnlighterJSRAW" data-enlighter-language="generic" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group=""># Method 3: match()
import re; print(re.match('.*F.*r', 'Learn Python with Finxter'))
# <re.Match object; span=(0, 25), match='Learn Python with Finxter'></pre>
The <code>match()</code> function finds the match of the pattern at the beginning of the string and returns a matching object. In this case, the whole string matches, so the match object encloses the whole string.
<h2>Method 4: fullmatch()</h2>
The re.fullmatch(pattern, string, flags=0) method returns a match object if the regex matches the whole string. Read more in <a href="https://blog.finxter.com/python-regex-fullmatch/">our blog tutorial</a>.
<pre class="EnlighterJSRAW" data-enlighter-language="generic" data-enlighter-theme="" data-enlighter-highlight="" data-enlighter-linenumbers="" data-enlighter-lineoffset="" data-enlighter-title="" data-enlighter-group=""># Method 4: fullmatch()
import re; print(re.fullmatch('.*F.*r.*', 'Learn Python with Finxter'))
#<re.Match object; span=(0, 25), match='Learn Python with Finxter'></pre>
The <code>fullmatch()</code> function attempts to match the whole string and returns a matching object if successful. In this case, the whole string matches, so the match object encloses the whole string.
<h2>Where to Go From Here?</h2>
Enough theory, let’s get some practice!
To become successful in coding, you need to get out there and solve real problems for real people. That’s how you can become a six-figure earner easily. And that’s how you polish the skills you really need in practice. After all, what’s the use of learning theory that nobody ever needs?
Practice projects is how you sharpen your saw in coding!
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