title: pandas loop filter running on dataframe iloc
body: <p>I am a beginner at python. I want to write a program that filtrates my data frame as a loop by category from a list. And then it will run on the filtered data and filtrate that again by another list.<br />
  Example:</p>
  <pre><code>df2 =df.loc[df[&quot;NOTES&quot;]==&quot;moshe&quot;]`
  df2.loc[df[&quot;CALENDAR_NAME&quot;]==&quot;QCM-D Sede-Boqer&quot;]
  supervisors = [&quot;moshe&quot;,&quot;roy&quot;,&quot;avner&quot;,&quot;roni&quot;,&quot;vered&quot;] # &quot;NOTES column&quot;
  calendars = [&quot;SEM&quot;,&quot;Contact Angle&quot; , &quot;TOC-AnalytikJena&quot;,&quot;QCM-D Sede-Boqer&quot;] # CALENDER NAME column
  </code></pre>