title: How do I open all files of a certain type in Python and process them?
body: <p>I'm trying to figure out how to make python go through a directory full of csv files, process each of the files and spit out a text file with a trimmed list of values.</p>
  
  <p>In this example, I'm iterating through a CSV with lots of different types of columns but all I really want are the first name, last name, and keyword. I have a folder full of these csvs with different columns (except they all share first name, last name, and keyword somewhere in the csv). What's the best way to open that folder, go through each csv file, and then spit it all out as either its own csv file for just a text list as I have in the example below. </p>
  
  <pre><code>import csv
  reader = csv.reader(open("keywords.csv"))
  rownum = 0
  headnum = 0
  F = open('compiled.txt','w')
  for row in reader:
      if rownum == 0:
          header = row;
          for col in row:
              if header[headnum]=='Keyword':
                  keywordnum=headnum;
              elif header[headnum]=='First Name':
                  firstnamenum=headnum;
              elif header[headnum]=='Last Name':
                  lastnamenum=headnum;
              headnum +=1
      else:
          currentrow=row
          print(currentrow[keywordnum] + '\n' + currentrow[firstnamenum] + '\n' + currentrow[lastnamenum]) 
          F.write(currentrow[keywordnum] + '\n')
  
      rownum +=1
  </code></pre>