python : Compare two large files

Question

这是 Compare two large files 的后续问题由 phihag 回答

我想在比较两个文件后显示不同的行数。想要在程序完成后显示为消息行数不同。

我的尝试:

with open(file2) as b:
  blines = set(b)
with open(file1) as a:
  with open(file3, 'w') as result:
    for line in a:
      if line not in blines:
        result.write(line)

lines_to_write = []
with open(file2) as b:
  blines = set(b)
with open(file1) as a:
  lines_to_write = [l for l in a if l not in blines]

print('count of lines are in difference:', len(lines_to_write))

Answer 1

如果可以将所有内容加载到内存中，则可以对集合执行以下操作:

union = set(alines).union(blines)
intersection = set(alines).intersection(blines)
unique = union - intersection

编辑:更简单(也更快)的是:

set(alines).symmetric_difference(blines)