title: Pandas return true if match on multiple column search?
body: <p>I'm trying to search over multiple columns and right now I'm getting the result but I really just need a true/false if there is a match.  Is there a way to do this?</p>
  <p>Here's a sample:</p>
  <pre><code>import pandas as pd
  import numpy as np
  df = pd.DataFrame(np.random.rand(10000, 5)*10, columns=list('ABCDE')).astype(int)
  df
  
      A   B   C   D   E
  0   1   9   2   9   2
  1   5   2   1   6   2
  2   8   6   9   8   5
  3   0   6   8   5   5
  4   1   2   4   8   4
  ... ... ... ... ... ...
  9995    9   3   4   9   0
  9996    2   4   1   3   7
  9997    4   5   2   4   9
  9998    7   5   0   3   2
  9999    3   5   0   5   7
  10000 rows × 5 columns
  
  df[((df['A'] == 0) &amp; (df['B'] == 1))]
  
  A   B   C   D   E
  5   0   1   7   0   6
  105 0   1   2   5   9
  375 0   1   0   0   3
  688 0   1   8   0   9
  770 0   1   7   9   5
  ... ... ... ... ... ...
  9706    0   1   1   7   4
  9710    0   1   4   4   9
  9789    0   1   3   4   3
  9810    0   1   1   1   5
  9987    0   1   2   3   3
  89 rows × 5 columns
  </code></pre>
  <p>Instead of getting the rows the data match, can I get true or false if the result exists in the dataframe?</p>