title: How to use grep for values <= smaller than equals bigger than equals?
body: <p>I need to <code>grep</code> values between a certain range.
  how would i write this?</p>
  
  <p>I tried different things e.g.
  for selecting everything between <code>0 and 1</code>   - call it A</p>
  
  <pre class="lang-sh prettyprint-override"><code>mydata[grep("&lt;=[1]","&gt;=[0]") , mydata_V1, perl= TRUE ), "new_variable" &lt;- "A"
  </code></pre>