CSV模块读入文件，位于其他文件夹（例如，我的下载文件夹）中

Question

so I want to use the csv module in order to read in some csv.files but I get the following errors with the given code:

########################### IMPORT MODULES ############################

import sys, time, glob, os, csv, student

######################### DEFINE PARAMETERS ###########################

timings_csv_file      = './timings.csv'
inputs_csv_file       = './inputs.csv'
testing_pair_csv_file = './testing_pair.csv'

############## LOAD TIMINGS INFORMATION AND TEST PAIR #################

csv_reader = csv.reader(open(timings_csv_file, 'rb'), delimiter=',')
timings = [int(element) for element in csv_reader.next()]

csv_reader = csv.reader(open(testing_pair_csv_file, 'rb'), delimiter=',')
testing_pair = [long(element) for element in csv_reader.next()]

csv_reader = csv.reader(open(inputs_csv_file, 'rb'), delimiter=',')
inputs = [long(element) for element in csv_reader.next()]

##################### PERFORM TIMING ATTACK ###########################

key = student.perform_timing_attack(inputs, timings, testing_pair)

######################## OUTPUT RESULTS ###############################

keyhex = ",".join(["%02X" % (key >> 64-(8*(i+1)) & 0x00000000000000FF ) for i in range(64/8) ])
print keyhex

################### WRITE RESULTS TO A FILE ###########################

keyF = open( "./key.txt", "w" )
keyF.write(keyhex)
keyF.close()

I get the upcoming Error Message:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/Amine/anaconda/lib/python2.7/site-packages/spyder/utils/site/sitecustomize.py", line 866, in runfile
    execfile(filename, namespace)
  File "/Users/Amine/anaconda/lib/python2.7/site-packages/spyder/utils/site/sitecustomize.py", line 94, in execfile
    builtins.execfile(filename, *where)
  File "/Users/Amine/Downloads/SIKA_Aufgabe_2/ga24feb_timings/framework/main.py", line 13, in <module>
    csv_reader = csv.reader(open(timings_csv_file, 'rb'), delimiter=',')
IOError: [Errno 2] No such file or directory: './timings.csv'

I think Python can not find the files in the current directory where it is actually looking for or running since I said: "./file.csv". As far as I know it is looking in its current directory. I know, that if I enter the whole path of the csv-files, it will work, but I want to make it independent of the file-path, thus the code has to be able to work always with the data in its own path.

So how do I have to change the path of Python in order to leave the csv-files where they are and still be able to use "./file.csv". Eg when I check what path Python is actually looking for by using "sys.path[0]" I get the output " '' " which I do not really understand because what the heck is '' for a path? Moreover, I tried to set my PYTHONPATH but I think the PYTHONPATH only involves data import for modules (is this right?).

So what should I do to set the path Python is looking for such that "./file.csv" works for me.

Thanks!

Answer 1

If you know that the files you are processing are always in the same path as your script as indicated by your statement "thus the code has to be able to work always with the data in its own path.", you can just call the file with its name (without the slash):

timings_csv_file      = 'timings.csv'
inputs_csv_file       = 'inputs.csv'
testing_pair_csv_file = 'testing_pair.csv'

this will work when you directory looks like this:

dir/
....script.py
....timings.csv
....inputs.csv
....testing_pair.csv

On the other hand if you want to go up one hierarchy level (i'm not quite sure if that was what you were going for?) you could do this:

timings_csv_file      = '../timings.csv'
inputs_csv_file       = '../inputs.csv'
testing_pair_csv_file = '../testing_pair.csv'

this will work when your folder structure looks like this:

dir/
....timings.csv
....inputs.csv
....testing_pair.csv
....python/
    ....script.py

Answer 2

Instead of,

timings_csv_file      = './timings.csv'
inputs_csv_file       = './inputs.csv'
testing_pair_csv_file = './testing_pair.csv'

use

import os
current_path = os.getcwd() 
timings_csv_file      = current_path + '\\timings.csv'
inputs_csv_file       = current_path + '\\inputs.csv'
testing_pair_csv_file = current_path + '\\testing_pair.csv'

This, gets the current working directory of your script and passes the complete path to library.