title: Pandas: Replacing Non-numeric cells with 0
body: <p>I have the Pandas Dataframe in this format</p>
  
  <pre><code>0          or LIST requests
  1                 us-west-2
  2                 1.125e-05
  3                         0
  4                 3.032e-05
  5                         0
  6                  7.28e-06
  7          or LIST requests
  8                   3.1e-07
  9                         0
  10                        0
  11                1.067e-05
  12               0.00011983
  13                0.1075269
  14         or LIST requests
  15                us-west-2
  16                        0
  17                 2.88e-06
  18           ap-northeast-2
  19                 5.52e-06
  20                 6.15e-06
  21                 3.84e-06
  22         or LIST requests
  </code></pre>
  
  <p>I want to replace all non-numeric cells with 0 in pandas. I am trying some thing like this but nothing works, </p>
  
  <pre><code>training_data['usagequantity'].replace({'^([A-Za-z]|[0-9]|_)+$': 0}, regex=True)
  </code></pre>
  
  <p>any hint how can I do this:</p>