title: Can I use regexes within datetime.strptime formats?
body: <p>I have string values that contain a trailing time stamp. I thought I could use strptime <strong>with</strong> a regex pattern to extract those. </p>
  
  <p>Like:</p>
  
  <pre><code>from __future__ import print_function
  
  from datetime import datetime
  # this here works
  input_with_ts = "20170410_1133"
  print(datetime.strptime(input_with_ts, '%Y%m%d_%H%M'))
  # but this is how things really look like
  input_with_ts = "foo_bar_D31_848_20170410_1133"
  print(datetime.strptime(input_with_ts, 'foo_bar_.*_.*_%Y%m%d_%H%M'))
  </code></pre>
  
  <p>Gives:</p>
  
  <pre><code>2017-04-10 11:33:00
  Traceback (most recent call last):
    File "test.py", line 9, in &lt;module&gt;
      print(datetime.strptime(input_with_ts, 'foo_bar_.*_.*_%Y%m%d_%H%M'))
    File "/usr/lib/python2.7/_strptime.py", line 332, in _strptime
  (data_string, format))
  ValueError: time data 'foo_bar_D31_848_20170410_1133' does not match format 'foo_bar_.*_.*_%Y%m%d_%H%M'
  </code></pre>
  
  <p>Simply wondering: is that even possible - putting a regex pattern into that format string? If not, what is the straight canonical way to get me there?</p>