title: create bar chart by accessing data from 2 .csv files
body: <p><code>.csv</code> file 1 data:</p>
  
  <pre><code>sampler_label,aggregate_report_count,average,aggregate_report_median,aggregate_report_90%_line
  HTTP Request1,  750               ,26339           ,22644               , 40210
  HTTP Request2,  750               ,8280       ,4781              ,21016      
  </code></pre>
  
  <p><code>.csv</code> file 2 data:</p>
  
  <pre><code>sampler_label,aggregate_report_count,average,aggregate_report_median,aggregate_report_90%_line
  HTTP Request1,  350               ,2539        ,2224                , 48410
  HTTP Request4,  350               ,8736       ,9285              ,38217
  </code></pre>
  
  <p>I want to display bar graph, which should depict values of average from both files for each sampler label.
  Here there are 2 average values in each file. there may be n number of values. in bar graph i want to display values of file 1 and file 2 in one graph only.
  Please help me....                          </p>