title: How to select the values in my dataframe which has logical operator "<" (less than), divide them by two, and convert all as.numeric
body: <p>I have a dataframe with character-type columns. I need to take each value as a string, find out if there is a logical operator exist. If it is TRUE, then divide it by two and there this numeric value. If there is NO logical operator, just put back here a number. At the end I would want to have all "numeric" values dataframe. 
  <a href="https://drive.google.com/open?id=1v6WuIetoZJvL4F4XYqCamBtBzvte1qjX" rel="nofollow noreferrer">This dataframe</a></p>
  
  <pre><code>1   &lt;0.0001 5.89    34.6    0.044   1.14    &lt;1  1.77    &lt;1  19.2    310 20.2    2.94    1.38    31.9    0.94    0.115   5.2 2.38    38.4    0.078
  2   &lt;0.0001 5.77    40.7    0.042   1.25    &lt;1  1.67    &lt;1  20.6    260 19.5    3.14    1.51    30.2    1.04    0.098   27.7    2.54    39.4    0.07
  3   &lt;0.0001 6.77    44.3    0.039   1.38    &lt;1  1.62    &lt;1  21.3    180 16.9    3.79    1.65    26.8    1.26    0.076   2.6 2.63    43.4    0.63
  </code></pre>