title: How to set the index of a pandas Dataframe to that of the length of the Columns?
body: <p>Okay so I have downloaded a sample csv for this from:
  <a href="https://people.sc.fsu.edu/%7Ejburkardt/data/csv/csv.html" rel="nofollow noreferrer">https://people.sc.fsu.edu/~jburkardt/data/csv/csv.html</a>
  My questions is this, I have imported a dataframe and indexed out some of the data. The code looks like this:</p>
  <pre><code>import pandas as pd
  
  df = pd.read_csv('/Users/benitocano/Downloads/airtravel.csv')
  
  df.head()
  And the output is:
      Month   &quot;1958&quot;  &quot;1959&quot;  &quot;1960&quot;
  0   JAN 340 360 417
  1   FEB 318 342 391
  2   MAR 362 406 419
  3   APR 348 396 461
  4   MAY 363 420 472
  </code></pre>
  <p>Now say that I index out month 3 to 7 like so:</p>
  <pre><code>import pandas as pd
  
  df = pd.read_csv('/Users/benitocano/Downloads/airtravel.csv')
  df = df[3:7]
  df.head()
  </code></pre>
  <p>And the output is:</p>
  <pre><code>    Month &quot;1958&quot; &quot;1959&quot; &quot;1960&quot;
  3   APR  348     396     461
  4   MAY  363     420     472
  5   JUN  435     472     535
  6   JUL  491     548     622
  </code></pre>
  <p>So my issue is now that I have indexed out the months, the DataFrame index now starts at 3 and goes to 6. How can I make it so that the index starts at 1 and goes to 4, though with the values from the second DataFrame? Thank You!</p>