title: In Pandas, how can I count consecutive positive and negatives in a row?
body: <p>In python pandas or numpy, is there a built-in function or a combination of functions that can count the number of positive or negative values in a row? </p>
  
  <p>This could be thought of as similar to a roulette wheel with the number of blacks or reds in a row.</p>
  
  <p>Example input series data: </p>
  
  <pre><code>Date
  2000-01-07    -3.550049
  2000-01-10    28.609863
  2000-01-11    -2.189941
  2000-01-12     4.419922
  2000-01-13    17.690185
  2000-01-14    41.219971
  2000-01-18     0.000000
  2000-01-19   -16.330078
  2000-01-20     7.950195
  2000-01-21     0.000000
  2000-01-24    38.370117
  2000-01-25     6.060059
  2000-01-26     3.579834
  2000-01-27     7.669922
  2000-01-28     2.739991
  2000-01-31    -8.039795
  2000-02-01    10.239990
  2000-02-02    -1.580078
  2000-02-03     1.669922
  2000-02-04     7.440186
  2000-02-07    -0.940185
  </code></pre>
  
  <p>Desired output:</p>
  
  <pre><code>-  in a row 5 times
  +  in a row 4 times
  ++  in a row once
  ++++  in a row once
  +++++++ in a row once
  </code></pre>