Why data frame column names different using = and <- in R : <p>Can any body explain why the below two data frames <code>df1</code> and <code>df2</code> are differing in their column names</p>

<pre><code>  df1 &lt;- data.frame(a = 1:5, b = 11:15)
  df1
  #   a  b
  # 1 1 11
  # 2 2 12
  # 3 3 13
  # 4 4 14
  # 5 5 15

  df2 &lt;- data.frame(a &lt;- 1:5, b &lt;- 11:15)
  df2
  #   a....1.5 b....11.15
  # 1        1         11
  # 2        2         12
  # 3        3         13
  # 4        4         14
  # 5        5         15
</code></pre>
