title: Calculate new column across multiple dataframes
body: <p>I am new to pandas and am looking to redo the following from multiple excel sheets with multiple dataframes.</p>
  
  <p>Here is the high-level structure:</p>
  
  <p><strong>Master_df</strong><br>
  Master_UID | Component_ID_1 | Quantity_1 | ... | Component_ID_8 | Quantity_8</p>
  
  <p><strong>Component_type_1_df</strong><br>
  Component_ID | ... | weight</p>
  
  <p><strong>Component_type_2_df</strong><br>
  Component_ID | ... | weight</p>
  
  <p>Master_UID['Component_ID_1'] contains 'Component_ID's from both Component_type_1_df and Component_type_2_df</p>
  
  <p>Now in <strong>Master_df</strong>, I'd like to create column <strong>Weight_1</strong> columns based on <strong>weight</strong> out of the 2 Component_type_X_df.</p>
  
  <p>multiplied by Master_df['Quantity_1'].</p>