title: Making a character string with column names with zero values
body: <p>The 4th column is my desired column. Video,Webinar,Meeting,Conference are the 4 type of activities that the different customers(names) can engage in. You can see,in a given row, all the column names with zero value are in the final column(NextStep) and the value there(character string separated by commas) excludes the column name with non-zero value. The character strings(column names) in the final column usually appear in the column order with two exceptions. Webinar always appears first if it has a zero value and video always appears last if it has a zero value.</p>
  
  <pre><code>    library(data.table)
       dt &lt;- fread('
   Name     Video   Webinar Meeting Conference   NextStep
    John       1         0        0       0         Webinar,Meeting,Conference
    John       1         1        0       0         Meeting,Conference
    John       1         1        1       0         Conference      
    Tom        0         0        1       0         Webinar,Conference,Video
    Tom        0         0        1       1         Webinar,Video   
    Kyle       0         0        0       1         Webinar,Meeting,Video
  
                                      ')
  </code></pre>
  
  <p>My question is how to create the next step column. Thanks a lot for your help!</p>