"ValueError: labels ['timestamp'] not contained in axis" error
<p>I have this code ,i want to remove the column 'timestamp' from the file :<a href="https://www.dropbox.com/s/4cksq4dwgbaqd07/u.data?dl=0" rel="noreferrer">u.data</a> but can't.It shows the error<br>
"ValueError: labels ['timestamp'] not contained in axis"
How can i correct it</p>

<pre><code>import numpy as np
import pandas as pd
import matplotlib.pyplot as plt 
plt.rc("font", size=14)
from sklearn.linear_model import LinearRegression
from sklearn.linear_model import Ridge
from sklearn.cross_validation import KFold
from sklearn.cross_validation import train_test_split



data = pd.read_table('u.data')
data.columns=['userID', 'itemID','rating', 'timestamp']
data.drop('timestamp', axis=1)


N = len(data)
print data.shape
print list(data.columns)
print data.head(10)
</code></pre>