how do I use my script to iterate over a folder and write the file name?

Question

I wrote a script that finds the maximum value in a log file. I can then write the max value to another file. My problem: a. is how do I run it against all the files in a directory b. write "Filename" + "Max Value" into 1 file.

here's my code:

  1 import re
  2
  3 a = 'NA total MB July.csv'
  4 b = 'Total.csv'
  5
  6 with open(a, 'r') as f1:
  7         with open(b,'w') as f2:
  8                 header = f1.readline()
  9                 data= f1.readlines()
 10                 pattern= re.compile(",|\s")
 11                 maxMB=[]
 12                 for line in data:
 13                         parts = pattern.split(line)
 14                         #print "Log line split",parts #splits the number
 15                         mbCount= parts[2] #index of the number
 16                         mbint=float(mbCount)
 17                         maxMB.append(mbint)# creates a list of all MBs
 18                         #print "MAX: ", maxMB #prints out the max MB
 19                 highest=max(maxMB)
 20                 print highest
 21                 f2.write(str(highest))#writes highest value to file

Here's my files output

167.94

What I'm looking to see in Total.csv is

NA total MB July : 167.94
NA total MB August: 123.45
...
..
. For all the csv files with in a folder

Can't quite figure out how to make this work without processing 1 file at a time and manually changing the file name. Any help to this n00b would be greatly appreciated. THANKS!

Answer 1

You can use os.listdir() to grab files in current directory.

files = [f for f in os.listdir('.') if os.path.isfile(f)]
for f in files:
    #do something

You can open Total.csv file in ab mode so that you can append all the max values into that one file only.

with open('Total.csv', 'ab') as out:
    writer = csv.writer(out, delimiter=',', quotechar='"',quoting=csv.QUOTE_ALL)
    row = (,)
    writer.writerow(row)