title: Formatting dataframe in appending
body: <p>I want to append 2 dataframes:</p>
  
  <pre><code>data1:
       a
  1    a
  2    b
  3    c
  4    d
  5    e
  
  data2:
       b
  1    f   
  2    g
  3    h
  4    i
  5    j
  
  output:
  
  1    a
  2    b
  3    c
  4    d
  5    e
  6    f   
  7    g
  8    h
  9    i
  10   j
  </code></pre>
  
  <p>currently i am using:</p>
  
  <pre><code>all_data= data1.append(data2, ignore_index=True)
  </code></pre>
  
  <p>this gives me result as:</p>
  
  <pre><code>     a    b
  1    a
  2    b
  3    c
  4    d
  5    e
  6        f   
  7        g
  8        h
  9        i
  10       j
  </code></pre>
  
  <p>i.e. in different columns. 
  How can i get them in the same column?</p>
  
  <p>Also tried converting the dataframes into list and then tring to append it. But it gave me the error:</p>
  
  <pre><code>TypeError: append() takes no keyword arguments
  </code></pre>
  
  <p>Also, is there any other function to remove duplicates from the datarame of strings? The drop_duplicates() function does not work in my case. The data still has duplicates.</p>