Python CSV比较

Question

This script compares two csv files...with two columns plz help me to modify this script if sample1.csv and sample2.csv has more than 2 columns or 1 column.

f1_in = open("sample1.csv","r")
next(f1_in,None)
f1_dict = {}
for line in f1_in:
  l = line.split(',')
  f1_dict[l[0]. strip()] = l[1]. strip() 
  l.sort()
f1_in.close()

f2_in = open("sample2.csv","r")
next(f2_in,None)
f2_dict = {}
for line in f2_in:
  l = line.split(',')
  f2_dict[l[0]. strip()] = l[1]. strip()
  l.sort()
f2_in.close()


f_same = open("same.txt","w")
f_different = open("different.txt","w")

for k1 in f1_dict.keys():
  if k1 in f2_dict.keys() \
      and f2_dict[k1] == f1_dict[k1]:
    f_same.write("{0}, {1}\n". format(str(k1)+" "+str(f1_dict[k1]),
                                    str(k1)+" "+str(f2_dict[k1])))

  elif not k1 in f2_dict.keys():
    f_different.write("{0}, {1}\n". format(str(k1)+" "+str(f1_dict[k1]),
                                           "------"))
  elif not f2_dict[k1] == f1_dict[k1]:
    f_different.write("{0}, {1}\n". format(str(k1)+" "+str(f1_dict[k1]),
                                           str(k1)+" "+str(f2_dict[k1])))

f_same.close()
f_different.close()

for eg:if my source file has Name and Salary as headers with values A 20000 B 15000 C 10000 D 10000 and target file also with Name and Salary has headers with values A 40000 D 10000 B 15000 C 10000 E 8000...my output should be Different lines:A 20000 A 40000 D 10000 -----(no file in target) -----(no file in source) E 8000 and common lines as B 15000 B 15000, C 10000 C 10000

Answer 1

It is no wonder you cannot expand the code to more than two colums if you are regarding your columns as key/value pairs in a dictionary.

You have to see them as "elements in a set". I understand this is why you are not using the csv module or the difflib module: because you do not care whether the lines appear in (nearly) same order in either file, but whether they appear at all.

Here is an example:

import itertools


def compare(first_filename, second_filename):
    lines1 = set()
    lines2 = set()
    with open(first_filename, 'r') as file1, \
            open(second_filename, 'r') as file2:
        for line1, line2 in itertools.izip_longest(file1, file2):
            if line1:
                lines1.add(line1)
            if line2:
                lines2.add(line2)
    print "Different lines"
    for line in lines1 ^ lines2:
        print line,
    print "---"
    print "Common lines"
    for line in lines1 & lines2:
        print line,

Notice that this code will find differences on both files, not just things that exist on f1 but not on f2, as your example does. However, it is not able to tell where do differences come from (since this does not seem a requirement of the question).

Check that it works

In [40]: !cat sample1.csv
bacon, eggs, mortar
whatever, however, whenever
spam, spam, spam

In [41]: !cat sample2.csv
guido, van, rossum
spam, spam, spam

In [42]: compare("sample1.csv", "sample2.csv")
Different lines
whatever, however, whenever
guido, van, rossum
bacon, eggs, mortar
---
Common lines
spam, spam, spam