title: Python read 100+ CSV files and return sum of a column from each CSV file into a new csv
body: <p>I have 100+ CSV files in the same folder. I'm trying to read all the files which don't have any sequence formatting except all files begin with &quot;AB_&quot;. I do not wish to concatenate all these files as these files are originally from a huge file split by ID using Python. I'm trying to verify that all these files are sum up to the right amount.
  These files are formatted as below:</p>
  <pre><code>ID   country   amount
  
  1234   Malaysia    30
  
  1234   Malaysia    80
  
  ....
  </code></pre>
  <p>All files have different number of rows, and ID column has only 1 distinct ID. I wish to have a CSV file created to summarize all these CSV files by having output as below (each row shows summary from each CSV file from the folder):</p>
  <pre><code>ID   sum_amount
  
  1234 110
  
  2345 88
  
  ...
  </code></pre>
  <p>Please help! Thanks!</p>