title: Cloud Dataflow to Join multiple files
body: <p>I am newbie to Google Cloud,I have below files in GCS, need to design a dataflow to merge the files and replace values from product,location files and load the final output file to BigQuery.</p>
  
  <ol>
  <li>gs://testprojectxxxx/staging/actual_file.csv</li>
  <li>gs://testprojectxxxx/staging_timestamp/product.csv
                                    /location.csv</li>
  </ol>
  
  <p><a href="https://i.stack.imgur.com/SB5t4.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SB5t4.jpg" alt="enter image description here"></a></p>
  
  <p><strong>Python code on local machine:</strong></p>
  
  <pre><code>import pandas as pd
  
  df1 = pd.read_csv("C:/Users/xxxx\\actual_file.csv")
  df2 = pd.read_csv("C:/Users/xxxx_folder\\product.csv",header=None,names=['id', 'product_name'])
  df3 = pd.merge(df1, df2, how='left', left_on='product_id', right_on='id')
  df3.drop(['product_id_x', 'id'], axis=1,inplace=True)
  
  df4 = pd.read_csv("C:/Users/xxxx_folder\\location.csv",header=None,names=['id', 'location_name'])
  df5 = pd.merge(df3, df4, how='left', left_on='location_id', right_on='id')
  df5.drop(['location_id_x', 'id'], axis=1,inplace=True)
  
  df5.rename(columns={'product_name_y':'product_name','location_name_y':'location'}, inplace=True)
  df5.to_csv('Final_file.csv', sep=',',encoding='utf-8', index=False)
  </code></pre>
  
  <p>Appreciate your help.</p>