title: python pandas convert a dictionary to a dataframe
body: <p>i have two dictionaries as follows. I can convert the first to a dataframe , but the second gives error. Why?</p>
  
  <pre><code>d = {'id': ['CS2_056'], 'cost': [2], 'name': ['Tap']}
  df = pd.DataFrame(d)
  print(df)
  
  raw_data1 = {
          'subject_id': 3,
          'first_name': 4, 
          'last_name': 7}
  raw_data1
  dfz = pd.DataFrame(raw_data1 )
  </code></pre>