title: Pandas equivalent rbind operation
body: <p>Basically, I am looping through a bunch of CSV files and in the end would like to <code>append</code> each dataframe into one. Actually, all I need is an <code>rbind</code> type function. So, I did some search and followed the <a href="http://pandas.pydata.org/pandas-docs/stable/merging.html" rel="noreferrer">guide</a>. However, I still could not get the ideal solution.</p>
  <p>A sample code is attached below. For instance shape of data1 is always 47 by 42. But shape of <code>data_out_final</code> becomes (47, 42), (47, 84), and (47, 126) after the first three files. Idealy, it should be (141, 42). In addition, I check index of <code>data1</code>, which is <code>RangeIndex(start=0, stop=47, step=1)</code>. Appreciate any suggestions!</p>
  <p>My <code>pandas</code> version is <code>0.18.1</code></p>
  <h2>code</h2>
  <pre><code>appended_data = []
  for csv_each in csv_pool:
      data1 = pd.read_csv(csv_each, header=0)
      # do something here
      appended_data.append(data2) 
  data_out_final = pd.concat(appended_data, axis=1)
  </code></pre>
  <p>If using <code>data_out_final = pd.concat(appended_data, axis=1)</code>, shape of data_out_final becomes (141, 94)</p>
  <h2>PS</h2>
  <p>kind of figure it out. Actually, you have to standardize column names before <code>pd.concat</code>.</p>