title: Use regex to extract number before a list of words in pandas dataframe
body: <p>I want to extract only the numbers before a list of specific words. Then put the extracted numbers in a new column.</p>
  <p>The list of words is: <code>l = [&quot;car&quot;, &quot;truck&quot;, &quot;van&quot;]</code>. I only put singular form here, but it should also apply to plural.</p>
  <pre><code>df = pd.DataFrame(columns=[&quot;description&quot;], data=[[&quot;have 3 cars&quot;], [&quot;a 1-car situation&quot;], [&quot;may be 2 trucks&quot;]])
  </code></pre>
  <p>We can call the new column for extracted number <code>df[&quot;extracted_num&quot;]</code></p>
  <p>Thank you!</p>