用Python编写格式正确的文本 [英] Writing nicely formatted text in Python

问题描述

在Python中，我正在使用以下代码编写文本文件:

f.write(filename + type + size + modified)

当然，输出看起来非常难看:

C:/Config/ControlSet/__db.006  file          56 KB   2012-Apr-30 10:00:46.467 AM
C:/Config/ControlSet dir       68881 KB   2012-Apr-30 10:00:46.396 AM 
C:/Config/DataStore.avlocate file           0 KB   2012-Apr-30 09:57:42.440 AM 
C:/Config/DataStoreLocate.bak file           0 KB   2012-Apr-30 09:57:42.470 AM 
C:/Config/DeviceConnections/devconn.bak file          41 KB   2012-Apr-30 10:39:50.181 AM   
C:/Config/DeviceConnections/devconn.cfg file          41 KB   2012-May-29 10:12:45.288 AM

但是我想对齐条目，使其看起来像这样:

C:/Config/ControlSet/__db.006                                            file          56 KB   2012-Apr-30 10:00:46.467 AM
C:/Config/ControlSet                                                      dir       68881 KB   2012-Apr-30 10:00:46.396 AM 
C:/Config/DataStore.avlocate                                             file           0 KB   2012-Apr-30 09:57:42.440 AM 
C:/Config/DataStoreLocate.bak                                            file           0 KB   2012-Apr-30 09:57:42.470 AM 
C:/Config/DeviceConnections/devconn.bak                                  file          41 KB   2012-Apr-30 10:39:50.181 AM   
C:/Config/DeviceConnections/devconn.cfg                                  file          41 KB   2012-May-29 10:12:45.288 AM

我的问题类似于此问题，除了我不知道文件名有多长时间会提前.我应该如何处理?

解决方案

如果您可以首先获取所有文件名的列表，则可以执行以下操作:

max_width = max(len(filename) for filename in filenames)
for filename in filenames:
    f.write(filename.ljust(max_width+1)+..whatever else..)

如果无法首先获取所有文件名的列表，则无法确保所有文件都对齐，因为无法知道以后是否会得到名称非常长的文件. /p>

但是，在这种情况下，我通常只假设N列通常就足够了，对于某些N，在这种情况下，您可以执行以下操作:

f.write('%-40s %6s %10s %2s\n' % (filename, type, size, modified))

In Python, I'm writing to a text file with code like:

f.write(filename + type + size + modified)

And of course the output looks really ugly:

C:/Config/ControlSet/__db.006  file          56 KB   2012-Apr-30 10:00:46.467 AM
C:/Config/ControlSet dir       68881 KB   2012-Apr-30 10:00:46.396 AM 
C:/Config/DataStore.avlocate file           0 KB   2012-Apr-30 09:57:42.440 AM 
C:/Config/DataStoreLocate.bak file           0 KB   2012-Apr-30 09:57:42.470 AM 
C:/Config/DeviceConnections/devconn.bak file          41 KB   2012-Apr-30 10:39:50.181 AM   
C:/Config/DeviceConnections/devconn.cfg file          41 KB   2012-May-29 10:12:45.288 AM

But I want to align the entries so it looks like this:

C:/Config/ControlSet/__db.006                                            file          56 KB   2012-Apr-30 10:00:46.467 AM
C:/Config/ControlSet                                                      dir       68881 KB   2012-Apr-30 10:00:46.396 AM 
C:/Config/DataStore.avlocate                                             file           0 KB   2012-Apr-30 09:57:42.440 AM 
C:/Config/DataStoreLocate.bak                                            file           0 KB   2012-Apr-30 09:57:42.470 AM 
C:/Config/DeviceConnections/devconn.bak                                  file          41 KB   2012-Apr-30 10:39:50.181 AM   
C:/Config/DeviceConnections/devconn.cfg                                  file          41 KB   2012-May-29 10:12:45.288 AM

My issue is similar to this question except I don't know how long the filenames will be beforehand. How should I approach this?

解决方案

If you can get a list of all filenames first, then you could do something like:

max_width = max(len(filename) for filename in filenames)
for filename in filenames:
    f.write(filename.ljust(max_width+1)+..whatever else..)

If you can't get a list of all filenames first, then there's no way to make sure that everything will line up, because there's no way to know if you'll later get a file whose name is really long.

In a case like this, though, I would usually just assume that N columns is generally sufficient, for some N, in which case you can just do something like:

f.write('%-40s %6s %10s %2s\n' % (filename, type, size, modified))

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