如何按字母順序在Python中連接多個排序文件？

Question

如何逐行讀取多個CSV輸入文件，比較每行中的字符，將第一行按字母順序寫入輸出文件，然后前進最小值文件的指針，繼續與所有文件進行比較，直到結束到達所有輸入文件。 這是一個針對解決方案的粗略計划。

buffer = []

for inFile in inFiles:

    f = open(inFile, "r")
    line = f.next()
    buffer.append([line, inFile])

#find minimum value in buffer alphabetically...
#write it to an output file...

#how do I advance one line in the file with the min value?
#and then continue the line-by-line comparisons in input files?

Answer 1

你可以使用heapq.merge ：

import heapq
import contextlib

files = [open(fn) for fn in inFiles]
with contextlib.nested(*files):
    with open('output', 'w') as f:
        f.writelines(heapq.merge(*files))

在Python 3.x（3.3+）中：

import heapq
import contextlib

with contextlib.ExitStack() as stack:
    files = [stack.enter_context(open(fn)) for fn in inFiles]
    with open('output', 'w') as f:
        f.writelines(heapq.merge(*files))