title: How to read multiple data sets, and create a single dataframe with a year column
body: <p>I would like to read multiple data sets and combine them into a single Pandas dataframe with a year column.</p>
  <p>My sample data sets include <code>newyork2000.txt</code>, <code>newyork2001.txt</code>, <code>newyork2002.txt</code>.</p>
  <p>Each data set contains <code>'address'</code> and <code>'price'</code>.</p>
  <p>Below is the <code>newyork2000.txt</code>:</p>
  <pre><code>253 XXX st, 150000
  2567 YYY st, 200000
  ...
  3896 ZZZ rd, 350000   
  </code></pre>
  <p>My final single dataframe should look like this:</p>
  <pre><code>year address      price
  2000 253 XXX st   150000
  2000 2567 YYY st  200000
  ...
  2000 3896 ZZZ rd  350000
  ...
  2002 789 XYZ ave  450000
  </code></pre>
  <p>So, I need to combine all data sets, create the year column, and name the columns.</p>
  <p>Here is my code to create a single dataframe:</p>
  <pre><code>years=[2000,2001,2002]
  df=[]
  for i years:
      df.append(pd.read_csv(&quot;newyork&quot; + str(i) + &quot;.txt&quot;, header=None))
  dfs=pd.concat(df)
  </code></pre>
  <p>But, I could not create the year column and name the columns. Please help me solve this problem.</p>