title: For-loop to read multiple .csv files in Python
body: <p>I started using Python and have the following problems here.</p>
  
  <ol>
  <li><p>Indentation Error with count +=1 and several other lines</p></li>
  <li><p>Not scanning all .csv files in a directory. When I run this script, it only shows outputs of only one .csv file instead of multiple .csv file outputs on the first column. There must be an issue with for loop commands that I have.</p></li>
  <li><p>I need to take the standard deviation of each line of the fileand take the mean value of standard deviation of all the lines in each file.</p>
  
  <pre><code>#!/usr/bin/env python
  
  import os
  
  print "Filename, Min, Max, Average, Mean of Std"
  for file in os.listdir("."):
      if not file.endswith(".csv"):
              continue    
      csv = open(file)    
      sum = 0
      diff = 0
      std = 0
      sumstd = 0
      count = 0
      min = 0
      max = 0
  
      for line in csv.readlines():
          x = line.split(",")
          time  = x[0]
          value = float(x[1])
          sum  += value       
          if value &gt; max:
              max = value
  
          if 0 &lt; value &lt; min:
              min = value 
              count += 1
          avg = sum / count   
  
      import math
              count +=1
              diff += (value - avg)**2
              std = math.sqrt (diff / (count+1)-1)
              sumstd += std
              meanstd = sumstd/count
  
  
  print file + "," + str(min) + "," + str(max) + "," + str(avg) +  "," + str(meanstd)    
  </code></pre></li>
  </ol>