python - 如何逐行比较两个不同的文件并将差异写入第三个文件？

Question

我想比较两个文本文件，每个文件有三列。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，第三列是第一列、第二列 - 源节点、目标节点之间的权重)。

文件格式 - 文件 1、2

1 3 1
16 36 1

我试过了

Compare two files line by line and generate the difference in another file和 find difference between two text files with one item per line和 http://www.daniweb.com/software-development/python/threads/124932/610058#post610058

都不适合我。

我觉得是字符串比较的问题。我想比较第一列和第二列中的数字。如果两者不同，我想将其写入第三个文件。

任何帮助将不胜感激!

更新

我发布了以下我在@MK 发表他的评论后尝试过的代码。

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()

Answer 1

如果你在 *nix 系统上，最好的通用选项就是使用:

sort filea fileb | uniq -u

但是如果你需要使用Python:

您的代码会在外部文件的每次迭代中重新打开内部文件。在循环外打开它。

使用嵌套循环的效率低于循环第一个存储找到的值，然后将第二个与这些值进行比较。

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")