title: pandas dataframe: make new dataframe from lookup and computation of existing dataframes
body: <p>Im trying to use data from two dateframes to create a new dataframe</p>
  
  <pre><code>lookup_data = [
  {   'item': 'apple',
      'attribute_1':3,
      'attribute_2':2,
      'attribute_3':10,
      'attribute_4':0,
  },
  {   'item': 'orange',
      'attribute_1':0.4,
      'attribute_2':20,
      'attribute_3':1,
      'attribute_4':9,
  },
  {   'item': 'pear',
      'attribute_1':0,
      'attribute_2':0,
      'attribute_3':30,
      'attribute_4':0,
  },
  {   'item': 'peach',
      'attribute_1':2,
      'attribute_2':2,
      'attribute_3':3,
      'attribute_4':6,
  },]
  
  df_lookup_data = pd.DataFrame(lookup_data,dtype=float)
  df_lookup_data.set_index('item', inplace=True, drop=True)
  
  collected_data = [
  {   'item':'apple',
      'qnt': 4},
  {   'item':'orange',
      'qnt': 2},
  {   'item':'pear',
      'qnt': 7},
  ]
  
  df_collected_data = pd.DataFrame(collected_data,dtype=float)
  df_collected_data.set_index('item', inplace=True, drop=True)
  
  df_result = pd.DataFrame(
      .... first column is item type
      .... second column is qnt*attribute_1
      .... second column is qnt*attribute_2
      .... second column is qnt*attribute_3
      .... second column is qnt*attribute_4
  )
  df_result.columns = ['item', 'attribute_1', 'attribute_2', 'attribute_3', 'attribute_4']
  print(result)
  </code></pre>
  
  <p>the result should print</p>
  
  <pre><code>   item    attribute_1  attribute_2  attribute_3  attribute_4
  0  apple   14           8            40           0
  1  orange  0.8          40           2            18
  2  pear    0            0            210           0
  </code></pre>
  
  <p>but im really not sure how i get date from these two dataframes and make this new one</p>