title: Filtering data in a dataframe based on criteria
body: <p>I am new to R and can't get to grips with this concept. Suppose I have a table loaded called "places" with 3 say columns - city, population and average summer temperature</p>
  
  <p>Say I want to "filter" - produce a new table object where population is less than 1 million and average summer temperature is greater than 70 degrees.</p>
  
  <p>In any other program I have used this would be pretty easy but having done some research I'm working myself up into greater confusion. Given the purpose of R and what it does this must be pretty simple stuff.</p>
  
  <p>How would I apply the above conditions to the table? What would the steps be? From what i understand, I cannot easily just select the table headings based on their name, which would be nice (e.g. WHERE city &lt; 1,000,000 )</p>