在python中使用split()和join()时保留空格 [英] Preserve whitespaces when using split() and join() in python

问题描述

我有一个数据文件，其中包含类似

I have a data file with columns like

BBP1   0.000000  -0.150000    2.033000  0.00 -0.150   1.77

，各个列之间以不同数量的空格分隔.

and the individual columns are separated by a varying number of whitespaces.

我的目标是读这些行，对几行进行一些数学运算，例如将第4列乘以0.95，然后将它们写到新文件中.新文件应该看起来像原始文件，除了我修改的值.

My goal is to read in those lines, do some math on several rows, for example multiplying column 4 by .95, and write them out to a new file. The new file should look like the original one, except for the values that I modified.

我的方法是将行作为列表项读取.然后，在感兴趣的行上使用split()，这将为我提供一个包含各个列值的子列表.然后，我进行修改，将各列一起join()，并将列表中的行写入新的文本文件.

My approach would be reading in the lines as items of a list. And then I would use split() on those rows I am interested in, which will give me a sublist with the individual column values. Then I do the modification, join() the columns together and write the lines from the list to a new text file.

问题是我有那些数量不等的空白.我不知道如何像阅读它们一样介绍它们.我唯一想到的方法是在分割字符之前先对行中的字符进行计数，这将非常繁琐.有人有更好的主意来解决这个问题吗?

The problem is that I have those varying amount of whitespaces. I don't know how to introduce them back in the same way I read them in. The only way I could think of is to count characters in the line before I split them, which would be very tedious. Does someone have a better idea to tackle this problem?

推荐答案

在这种情况下，您想将re.split()与一个组一起使用:

You want to use re.split() in that case, with a group:

re.split(r'(\s+)', line)

将同时返回列和的空白，因此您以后可以在包含相同数量的空白的情况下重新加入该行.

would return both the columns and the whitespace so you can rejoin the line later with the same amount of whitespace included.

示例:

>>> re.split(r'(\s+)', line)
['BBP1', '   ', '0.000000', '  ', '-0.150000', '    ', '2.033000', '  ', '0.00', ' ', '-0.150', '   ', '1.77']

您可能要做要从最后删除换行符.

You probably do want to remove the newline from the end.

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