title: How do I maintain an order after creating a list from a data.frame
body: <p>I have a data.frame in R, myTable consisting of a date , myDate; integer, myCount and factor ,myCategory. It is sorted by date</p>
  
  <p>I need to create a list from the data.frame (in order to plot a Highcharts graph in rCharts) </p>
  
  <pre><code>mySeries &lt;- lapply(split(myTable, myTable$myCategory), function(x) {
    res &lt;- lapply(split(x, rownames(x)), as.list)
    names(res) &lt;- NULL
    return(res)
  })
  </code></pre>
  
  <p>However, the resulting list is not ordered by myDate within myCategory. How can this be achieved? 
  myTable shown below</p>
  
  <p>TIA</p>
  
  <pre><code>myTable &lt;- structure(list(myDate = structure(c(15642, 15649, 15656, 15663, 
  15670, 15670, 15677, 15677, 15684, 15684, 15691, 15691, 15698, 
  15698, 15705, 15705, 15712, 15712, 15719, 15719, 15726, 15726, 
  15733, 15733, 15740, 15740, 15747, 15747, 15754, 15754, 15761, 
  15761, 15768, 15768, 15775, 15775, 15782, 15782, 15789, 15789, 
  15796, 15796, 15803, 15803, 15810, 15810, 15817, 15817, 15824, 
  15824, 15831, 15831, 15838, 15838, 15845, 15845, 15852, 15852, 
  15859, 15859, 15866, 15866), class = "Date"), myCount = c(142L, 
  338L, 350L, 324L, 490L, 4L, 567L, 178L, 414L, 113L, 489L, 195L, 
  241L, 168L, 355L, 164L, 1215L, 253L, 2171L, 222L, 1916L, 437L, 
  1820L, 420L, 1897L, 356L, 1632L, 381L, 1571L, 464L, 1835L, 620L, 
  1348L, 500L, 1398L, 448L, 2668L, 461L, 2510L, 456L, 2654L, 733L, 
  1977L, 617L, 1645L, 523L, 1857L, 550L, 1247L, 477L, 1286L, 560L, 
  1168L, 719L, 1264L, 649L, 1162L, 682L, 1149L, 801L, 1450L, 1018L
  ), myCategory = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 1L, 2L, 1L, 
  2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 
  2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 
  2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 
  2L, 1L, 2L, 1L, 2L), .Label = c("A", "B"), class = "factor")), .Names = c("myDate", 
  "myCount", "myCategory"), row.names = c(62L, 59L, 56L, 55L, 51L, 
  52L, 47L, 48L, 49L, 50L, 53L, 54L, 60L, 61L, 57L, 58L, 45L, 46L, 
  39L, 40L, 1L, 2L, 23L, 24L, 35L, 36L, 41L, 42L, 31L, 32L, 27L, 
  28L, 11L, 12L, 33L, 34L, 37L, 38L, 43L, 44L, 17L, 18L, 15L, 16L, 
  7L, 8L, 3L, 4L, 29L, 30L, 19L, 20L, 13L, 14L, 9L, 10L, 21L, 22L, 
  </code></pre>