title: How to load .mat files in Python, and access columns individually?
body: <p>I can load the .mat file, but as columns have no names, I don't know how to reference them.</p>
  
  <p>The .mat file consists of four columns, with a lot of rows.</p>
  
  <pre><code>import numpy as np 
  import pandas as pd
  from scipy.io import loadmat
  from sklearn.preprocessing import PolynomialFeatures 
  
  
  data = loadmat('data.mat')
  data.keys()
  </code></pre>
  
  <p>This results in: <code>data['no names for columns in mat file']</code></p>
  
  <p>What is wrong with this code?</p>