title: Plotting multiple smooth lines from a dataframe
body: <p>I am relatively new to R. I am trying to plot a dataframe loaded from a csv file. The data consists of 6 columns like this:</p>
  
  <pre><code>xval,col1,col2,col3,col4,col5
  </code></pre>
  
  <p>The first column (xval) consist of a sequence of monotonically increasing positive integers (e.g. 10, 40, 60 etc), the other columns columns 1 to 5, consist of floating point numbers.</p>
  
  <p>I want to create a plot in R as follows:</p>
  
  <ul>
  <li>plot xval term on x axis</li>
  <li>plot remaining columns (col1 ... col5) lines</li>
  <li>create a legend legend with col2, ... col5 renamed</li>
  </ul>
  
  <p>The data to be plotted (col1, ... col5) are 'snapshot' values so although I want to plot them as lines, I want the lines to be smoothed (i.e. interpolated).</p>
  
  <p>I am looking for a snippet that help me create the plot once I have read the data into a dataframe. Any help will be appreciated.</p>