如何逐行比较两个不同的文件并在第三个文件中写入差异? [英] How to compare two different files line by line and write the difference in third file?

问题描述

我想比较每个都有三列的两个文本文件.一个文件有999行，另一个文件有757行.我希望将不同的242行存储在不同的文件中.我使用随机网络生成器创建了第一个文件(999行)(999行是边，第三列是第一，第二列之间的权重-源节点和目标节点).

I would like to compare two text files which have three columns each. One file has 999 rows and another has 757 rows. I want the different 242 rows to be stored in a different file. I created the first file (999 rows) using a random network generator (999 rows are edges with third column being weight between first, second columns - source, destination nodes).

文件格式-文件1、2

1 3 1
16 36 1

我尝试过

比较两个文件逐行生成另一个文件中的差异 和 找到两个文本文件之间的差异，每个文本文件一个和 http://www.daniweb. com/software-development/python/threads/124932/610058#post610058

都没有为我工作.

我认为这是字符串比较的问题.我想比较第一列和第二列中的数字.如果它们都不相同，我想将其写入第三个文件.

I think it is a problem of string comparison. I would like to compare the numbers in first column and second column. If they both are different, I want to write it to third file.

任何帮助将不胜感激！

更新

我正在发布以下代码，我在@MK发表他的评论后尝试过.

I am posting the following code that I tried after @MK posted his comment.

f = open("results.txt","w")

for line in file("100rwsnMore.txt"):
    rwsncount += 1
    line = line.split()
    src = line[0]
    dest = line[1]
    for row in file("100rwsnDeleted.txt"):
        row = row.split()
        s = row[0]
        d = row[1]
        if(s != src and d != dest):
             f.write(str(s))
             f.write(' ')
             f.write(str(d))
             f.write('\n')

f.close()

推荐答案

如果您使用的是* nix系统，最好的通用选择就是使用:

The best general-purpose option if you're on a *nix system is just to use:

sort filea fileb | uniq -u

但是如果您需要使用Python:

But if you need to use Python:

您的代码在外部文件的每次迭代中都会重新打开内部文件.在循环外打开它.

Your code reopens the inner file in every iteration of the outer file. Open it outside the loop.

使用嵌套循环比循环遍历第一个存储找到的值，然后将第二个与这些值进行比较的效率低.

Using a nested loop is less efficient than looping over the first storing the found values, and then comparing the second to those values.

def build_set(filename):
    # A set stores a collection of unique items.  Both adding items and searching for them
    # are quick, so it's perfect for this application.
    found = set()

    with open(filename) as f:
        for line in f:
            # [:2] gives us the first two elements of the list.
            # Tuples, unlike lists, cannot be changed, which is a requirement for anything
            # being stored in a set.
            found.add(tuple(sorted(line.split()[:2])))

    return found

set_more = build_set('100rwsnMore.txt')
set_del = build_set('100rwsnDeleted.txt')

with open('results.txt', 'w') as out_file:
   # Using with to open files ensures that they are properly closed, even if the code
   # raises an exception.

   for res in (set_more - set_del):
      # The - computes the elements in set_more not in set_del.

      out_file.write(" ".join(res) + "\n")      

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