title: Python Regex multi group pattern findall() returning empty list
body: <p>I am trying to use Regex multi group pattern to extract different CPU specs from a line, but getting an empty list.When i try individual groups separately, i am able to extract corresponding values. How should i use multi group pattern here? Please help!</p>
  
  <pre><code>import re
  
  line = "R7000 CPU at 160MHz, Implementation 39, Rev 2.1, 256KB L2, 512KB L3 Cache"
  
  pat_cpu_values_combined = r"(?P&lt;freq&gt;\s+\w+Hz)(?P&lt;L2&gt;\s+\w+\s+L2)(?P&lt;L3&gt;\s+\w+\s+L3)"
  pat_cpu_freq = r"(?P&lt;freq&gt;\s+\w+Hz)"
  pat_cpu_l2 = r"(?P&lt;L2&gt;\s+\w+\s+L2)"
  pat_cpu_l3 = r"(?P&lt;L3&gt;\s+\w+\s+L3)"
  
  # empty list coming when pat_cpu_values_combined is searched
  
  print re.findall(pat_cpu_values_combined, line)
  
  # below individual group pattern findall are working fine
  
  print re.findall(pat_cpu_freq, line)
  print re.findall(pat_cpu_l2, line)
  print re.findall(pat_cpu_l3, line)
  </code></pre>