为什么此替换方法无法正常工作答案

【问题标题】：Why is this replace method not working properly为什么此替换方法无法正常工作
【发布时间】：2019-10-01 02:26:35
【问题描述】：

我有一个文件，其中的数据如下所示：

1 1:-0.03125 2:0.236364 3:0.142857 4:-0.107438 5:0.129032 6:0.163636 7:0.242105
2 1:-0.03125 2:0.472727 3:0.761905 4:0.123967 6:0.472727 7:0.347368
....

总共有几千行。我正在尝试将其转换为 csv 文件。

我尝试了以下代码：

with open("file1.test", "r") as infile:
    with open("file1.csv", "w") as outfile:
        for line in infile:
            new_line = line
            i = 1
            for i in range(1,8):
                to_replace = " " + str(i) + ":"
                new_line = new_line.replace(to_replace, ",", 1)
            new_line = line[:2] + "," + line[2:]
            new_line = new_line.replace(" ", "", 1)

但它没有按预期工作。 new_line = new_line.replace(" ", "", 1) 行有效，但是当我尝试用逗号替换“1：”时，它不会更新。我希望我的最终文件看起来像“

1, -0.03125,0.236364,0.142857,-0.107438,0.129032,0.163636,0.242105
2,-0.03125,0.472727,0.761905,0.123967,0.472727,0.347368

任何想法我做错了什么？

【问题讨论】：

您的.replace()s 可能一切正常。但是，您放弃了使用声明 new_line = line[:2] + "," + line[2:] 的所有工作，它仅使用 line 的原始值。

标签： python string replace

【解决方案1】：

您可以对每一行尝试这种转换方法：

>>> a = '1 1:-0.03125 2:0.236364 3:0.142857 4:-0.107438 5:0.129032 6:0.163636 7:0.242105'
>>> ','.join( [i.split(':')[-1] for i in a.split()] )
'1,-0.03125,0.236364,0.142857,-0.107438,0.129032,0.163636,0.242105'

你的整个程序看起来像这样：

with open("file1.test", "r") as infile:
    text = [i.strip() for i in infile.readlines()]

output = []
for t in text :
    output.append( ','.join( [i.split(':')[-1] for i in t.split()] ) )

with open("file1.csv", "w") as outfile:
    outfile.write( '\n'.join( output ) )

【讨论】：

【解决方案2】：

我喜欢这个

import re  
with open("file1.test", "r") as infile:
    with open("file1.csv", "w") as outfile:
        for line in infile:
            outfile.write(re.sub(' [1-7]:',',',line))

【讨论】：