创建文件，但如果名称存在，则添加编号 [英] Create file but if name exists add number

问题描述

Python是否有任何内置功能可在文件名中添加数字(如果已经存在)?

Does Python have any built-in functionality to add a number to a filename if it already exists?

我的想法是，它将以某些OS的工作方式工作-如果将文件输出到已经存在该名称文件的目录中，它将添加数字或递增数字.

My idea is that it would work the way certain OS's work - if a file is output to a directory where a file of that name already exists, it would append a number or increment it.

即，如果存在"file.pdf"，它将创建"file2.pdf"，并且下次创建"file3.pdf".

I.e: if "file.pdf" exists it will create "file2.pdf", and next time "file3.pdf".

推荐答案

在某种程度上，Python在tempfile模块中内置了此功能.不幸的是，您必须使用私有全局变量tempfile._name_sequence.这意味着tempfile正式不保证在将来的版本_name_sequence中甚至存在-它是一个实现细节. 但是，如果您可以使用它，可以说明如何在指定的目录(例如/tmp:

In a way, Python has this functionality built into the tempfile module. Unfortunately, you have to tap into a private global variable, tempfile._name_sequence. This means that officially, tempfile makes no guarantee that in future versions _name_sequence even exists -- it is an implementation detail. But if you are okay with using it anyway, this shows how you can create uniquely named files of the form file#.pdf in a specified directory such as /tmp:

import tempfile
import itertools as IT
import os

def uniquify(path, sep = ''):
    def name_sequence():
        count = IT.count()
        yield ''
        while True:
            yield '{s}{n:d}'.format(s = sep, n = next(count))
    orig = tempfile._name_sequence 
    with tempfile._once_lock:
        tempfile._name_sequence = name_sequence()
        path = os.path.normpath(path)
        dirname, basename = os.path.split(path)
        filename, ext = os.path.splitext(basename)
        fd, filename = tempfile.mkstemp(dir = dirname, prefix = filename, suffix = ext)
        tempfile._name_sequence = orig
    return filename

print(uniquify('/tmp/file.pdf'))

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