title: python pandas merge multiple csv files
body: <p>I have around 600 csv file datasets, all have the very same column names [‘DateTime’, ‘Actual’, ‘Consensus’, ‘Previous’, ‘Revised’], all economic indicators and all-time series data sets.</p>
  
  <p>the aim is to merge them all together in one csv file.</p>
  
  <p>With ‘DateTime’ as an index.</p>
  
  <p>The way I wanted this file to indexed in is the time line way which means let’s say the first event in the first csv dated in 12/18/2017 10:00:00 and first event in the second csv dated in 12/29/2017 09:00:00 and first event in the third csv dated in 12/20/2017 09:00:00.</p>
  
  <p>So, I want to index them the later first and the newer after it, etc. despite the source csv it originally from.</p>
  
  <p>I tried to merge just 3 of them as an experiment and the problem is the ‘DateTime’ because it prints the 3 of them together like this ('12/18/2017 10:00:00', '12/29/2017 09:00:00', '12/20/2017 09:00:00')
  Here is the code:</p>
  
  <pre><code>import pandas as pd
  
  
  df1 = pd.read_csv("E:\Business\Economic Indicators\Consumer Price Index - Core (YoY) - European Monetary Union.csv")
  df2 = pd.read_csv("E:\Business\Economic Indicators\Private loans (YoY) - European Monetary Union.csv")
  df3 = pd.read_csv("E:\Business\Economic Indicators\Current Account s.a - European Monetary Union.csv")
  
  df = pd.concat([df1, df2, df3], axis=1, join='inner')
  df.set_index('DateTime', inplace=True)
  
  print(df.head())
  df.to_csv('df.csv')
  </code></pre>