python - 匹配一行，追加在它下面

Question

我正在尝试编辑文件的格式，不对，它看起来像这样:

>Cluster 0
L07510
>Cluster 1
AF480591
AY457083
>Cluster 2
M88154
>Cluster 3
CP000924
L09161
>Cluster 4
AY742307
>Cluster 5
L09163
L09162
>Cluster 6
AF321086
>Cluster 7
DQ666175
>Cluster 8
DQ288691

我想用 python 写一些东西，它会遍历每一行，停在说“>Cluster x”(x 是一个数字)的行，然后将该数字添加到它后面的任何行。然后，当到达新的“>Cluster x”时，它会以新的 x 值重新开始。

所以它看起来像这样:

>Cluster 0
0 L07510
>Cluster 1
1 AF480591
1 AY457083
>Cluster 2
2 M88154
>Cluster 3
3 CP000924
3 L09161
>Cluster 4
4 AY742307
>Cluster 5
5 L09163
5 L09162
>Cluster 6
6 AF321086
>Cluster 7
7 DQ666175
>Cluster 8
8 DQ288691

我想我可以使用 regex，搜索 ">Cluster x"(regex 看起来像这样吗？('\>Cluster\d+')) 然后让程序在这个匹配的正则表达式之后的每一行附加 \d+ 是什么。我只是不确定如何实际写这个。任何帮助将不胜感激!

Answer 1

测试

# If you're on a POSIX compliant system, and this script is marked as 
# executable, the following line will make this file be automatically 
# run by the Python interpreter rather than interpreted as a shell script
#!/usr/bin/env python

# We need the sys module to read arguments from the terminal
import sys

# Open the input file, default mode is 'r', readonly, which is a safe default
infile = open(sys.argv[1])

# Prepare a variable for the cluster number to be used within the loop
cluster = ''

# loop through all lines in the file, but first set up a list comprehension
# that strips the newline character off the line for each line that is read
for line in (line.strip() for line in infile):
    if line.startswith('>'):
        # string.split() splits on whitespace by default
        # we want the cluster number at index 1
        cluster = line.split()[1]

        # output this line to stdout unmodified
        print line

    else:
        # output any other line modified by adding the cluster number
        print cluster + ' ' + line

用法

$ python cluster_format.py input.txt > output.txt