如何在Python 3中使用pathlib模块处理文件系统路径

我会带着你远行 2022-11-28 15:27 190阅读 0赞

*The author selected the [COVID-19 Relief Fund][] to receive a donation as part of the [Write for DOnations][] program.*

*作者选择了[COVID-19救济基金][COVID-19 Relief Fund]来接受捐赠，这是[Write for DOnations][]计划的一部分。*

### 介绍 **(**Introduction**)** ###

Python 3 includes [the `pathlib` module][the _pathlib_ module] for manipulating filesystem paths agnostically whatever the operating system. `pathlib` is similar to the [`os.path` module][os.path_ module], but `pathlib` offers a higher level—and often times more convenient—interface than `os.path`.

Python 3包含[`pathlib`模块，][the _pathlib_ module]用于在任何操作系统下[`pathlib`][the _pathlib_ module]不可知论的方式处理文件系统路径。 `pathlib`与[`os.path`模块][os.path_ module]类似，但是`pathlib`提供了比`os.path`更高级别的接口，并且常常是更方便的接口。

We can identify files on a computer with hierarchical paths. For example, we might identify the file `wave.txt` on a computer with this path: `/Users/sammy/ocean/wave.txt`. Operating systems represent paths slightly differently. Windows might represent the path to the `wave.txt` file like `C:\Users\sammy\ocean\wave.txt`.

我们可以识别具有分层路径的计算机上的文件。 例如，我们可以在具有以下路径的计算机上标识文件`wave.txt` ： `/Users/ sammy /ocean/wave.txt` 。 操作系统代表的路径略有不同。 Windows可能表示`wave.txt`文件的路径，例如`C:\Users\ sammy \ocean\wave.txt` 。

You might find the `pathlib` module useful if in your Python program you are creating or moving files on the filesystem, listing files on the filesystem that all match a given extension or pattern, or creating operating system appropriate file paths based on collections of raw strings. While you might be able to use other tools (like the `os.path` module) to accomplish many of these tasks, the `pathlib` module allows you to perform these operations with a high degree of readability and minimal amount of code.

如果在Python程序中正在创建或移动文件系统上的文件，列出与给定扩展名或模式都匹配的文件系统上的文件，或者基于原始字符串的集合创建适合操作系统的文件路径，则可能会发现`pathlib`模块很有用。 虽然您可以使用其他工具(例如`os.path`模块)来完成许多任务，但`pathlib`模块使您能够以高度的可读性和最少的代码执行这些操作。

In this tutorial, we’ll go over some of the ways to use the `pathlib` module to represent and manipulate filesystem paths.

在本教程中，我们将介绍一些使用`pathlib`模块表示和操作文件系统路径的方法。

## 先决条件 **(**Prerequisites**)** ##

To get the most out of this tutorial, it is recommended to have some familiarity with programming in Python 3. You can review these tutorials for the necessary background information:

为了充分利用本教程，建议您熟悉Python 3的编程。您可以查看以下教程以获取必要的背景信息：

*  [How To Code in Python 3][]
    
    [如何在Python 3中编码][How To Code in Python 3]

## 构造`Path`实例 **(**Constructing `Path` Instances**)** ##

The `pathlib` module provides several [classes][], but one of the most important is the `Path` class. Instances of the `Path` class represent a path to a file or directory on our computer’s filesystem.

`pathlib`模块提供了几个[类][classes] ，但是最重要的一个是`Path`类。 `Path`类的实例表示我们计算机文件系统上文件或目录的路径。

For example, the following code instantiates a `Path` instance that represents part of the path to a `wave.txt` file:

例如，以下代码实例化一个`Path`实例，该实例代表`wave.txt`文件的路径的`wave.txt` ：

from pathlib import Path
    
    wave = Path("ocean", "wave.txt")
    print(wave)

If we run this code, we’ll receive output like the following:

如果运行此代码，我们将收到类似以下的输出：

Output ocean/wave.txt

`from pathlib import Path` makes the `Path` class available to our program. Then `Path("ocean", "wave.txt")` instantiates a new `Path` instance. Printing the output shows that Python has added the appropriate operating system separator of `/` between the two path components we gave it: `"ocean"` and `"wave.txt"`.

`from pathlib import Path`使`Path`类可用于我们的程序。 然后， `Path("ocean", "wave.txt")`实例化一个新的`Path`实例。 打印输出显示Python在我们给它的两个路径组件`"ocean"`和`"wave.txt"`之间添加了`/`的适当的操作系统分隔符。

**Note:** Depending on your operating system, your output may vary slightly from the example outputs shown in this tutorial. If you are running Windows, for example, your output for this first example might look like `ocean\wave.txt`.

**注意：**根据您的操作系统，您的输出可能与本教程中显示的示例输出略有不同。 例如，如果您正在运行Windows，则第一个示例的输出可能类似于`ocean\wave.txt` 。

Currently, the `Path` object assigned to the `wave` variable contains a [*relative path*][relative path]. In other words, `ocean/wave.txt` might exist in several places on our filesystem. As an example, it may exist in `/Users/user_1/ocean/wave.txt` or `/Users/user_2/research/ocean/wave.txt`, but we haven’t specified exactly which one we are referring to. An [*absolute path*][relative path], by contrast, unambiguously refers to one location on the filesystem.

当前，分配给`wave`变量的`Path`对象包含一个[*相对路径*][relative path] 。 换句话说， `ocean/wave.txt`可能存在于我们文件系统上的多个位置。 例如，它可能存在于`/Users/ user_1 /ocean/wave.txt`或`/Users/ user_2 /research/ocean/wave.txt` ，但我们没有确切指定我们要指的是哪一个。 相反， [*绝对路径*][relative path]明确指向文件系统上的一个位置。

You can use `Path.home()` to get the absolute path to the home directory of the current user:

您可以使用`Path.home()`获取当前用户的主目录的绝对路径：

home = Path.home()
    wave_absolute = Path(home, "ocean", "wave.txt")
    print(home)
    print(wave_absolute)

If we run this code, we’ll receive output roughly like the following:

如果运行此代码，我们将大致收到如下所示的输出：

Output /Users/sammy
    /Users/sammy/ocean/wave.txt

**Note:** As mentioned earlier, your output will vary depending on your operating system. Your home directory, of course, will also be different than `/Users/sammy`.

**注意：**如前所述，您的输出将取决于您的操作系统。 当然，您的主目录也将不同于`/Users/ sammy` 。

`Path.home()` returns a `Path` instance with an absolute path to the current user’s home directory. We then pass in this `Path` instance and the strings `"ocean"` and `"wave.txt"` into another `Path` constructor to create an absolute path to the `wave.txt` file. The output shows the first line is the home directory, and the second line is the home directory plus `ocean/wave.txt`.

`Path.home()`返回带有当前用户主目录绝对路径的`Path`实例。 然后，我们将此`Path`实例以及字符串`"ocean"`和`"wave.txt"`到另一个`Path`构造函数中，以创建`wave.txt`文件的绝对路径。 输出显示第一行是主目录，第二行是主目录加`ocean/wave.txt` 。

This example also illustrates an important feature of the `Path` class: the `Path` constructor accepts both strings and preexisting `Path` objects.

此示例还说明了`Path`类的重要功能： `Path`构造函数同时接受字符串和预先存在的`Path`对象。

Let’s look at the support of both strings and `Path` objects in the `Path` constructor a little more closely:

让我们更仔细地研究一下`Path`构造函数中字符串和`Path`对象的支持：

shark = Path(Path.home(), "ocean", "animals", Path("fish", "shark.txt"))
    print(shark)

If we run this Python code, we’ll receive output similar to the following:

如果运行此Python代码，我们将收到类似于以下内容的输出：

Output /Users/sammy/ocean/animals/fish/shark.txt

`shark` is a `Path` to a file that we constructed using both `Path` objects (`Path.home()` and `Path("fish", "shark.txt")`) and strings (`"ocean"` and `"animals"`). The `Path` constructor intelligently handles both types of objects and cleanly joins them using the appropriate operating system separator, in this case `/`.

`shark`是一个`Path`到一个文件，我们使用这两种构建`Path` (对象`Path.home()`和`Path("fish", "shark.txt")`和字符串( `"ocean"`和`"animals"` )。 `Path`构造函数智能地处理这两种类型的对象，并使用适当的操作系统分隔符(在本例中为`/`干净地将它们连接在一起。

## 访问文件属性 **(**Accessing File Attributes**)** ##

Now that we’ve learned how to construct `Path` instances, let’s review how you can use those instances to access information about a file.

现在，我们已经学习了如何构造`Path`实例，让我们回顾一下如何使用这些实例访问有关文件的信息。

We can use the `name` and `suffix` attributes to access file names and file suffixes:

我们可以使用`name`和`suffix`属性来访问文件名和文件后缀：

wave = Path("ocean", "wave.txt")
    print(wave)
    print(wave.name)
    print(wave.suffix)

Running this code, we’ll receive output similar to the following:

运行此代码，我们将收到类似于以下内容的输出：

Output /Users/sammy/ocean/wave.txt
    wave.txt
    .txt

This output shows that the name of the file at the end of our path is `wave.txt` and the suffix of that file is `.txt`.

此输出显示路径末尾的文件名为`wave.txt` ，该文件的后缀为`.txt` 。

`Path` instances also offer the `with_name` function that allow you to seamlessly create a new `Path` object with a different name:

`Path`实例还提供了`with_name`函数，该函数使您可以无缝创建具有不同名称的新`Path`对象：

wave = Path("ocean", "wave.txt")
    tides = wave.with_name("tides.txt")
    print(wave)
    print(tides)

If we run this, we’ll receive output like the following:

如果运行此命令，我们将收到类似以下的输出：

ocean/wave.txt
    ocean/tides.txt

The code first constructs a `Path` instance that points to a file named `wave.txt`. Then, we call the `with_name` method on `wave` to return a second `Path` instance that points to a new file named `tides.txt`. The `ocean/` directory portion of the path remains unchanged, leaving the final path as `ocean/tides.txt`

该代码首先构造一个`Path`实例，该实例指向名为`wave.txt`的文件。 然后，我们调用`with_name`的方法`wave`返回第二个`Path`是个实例的文件名为`tides.txt` 。 路径的`ocean/`目录部分保持不变，最终路径保留为`ocean/tides.txt`

## 访问祖先 **(**Accessing Ancestors**)** ##

Sometimes it is useful to access directories that contain a given path. Let’s consider an example:

有时访问包含给定路径的目录很有用。 让我们考虑一个例子：

shark = Path("ocean", "animals", "fish", "shark.txt")
    print(shark)
    print(shark.parent)

If we run this code, we’ll receive output that looks like the following:

如果运行此代码，我们将收到类似于以下内容的输出：

Output ocean/animals/fish/shark.txt
    ocean/animals/fish

The `parent` attribute on a `Path` instance returns the most immediate ancestor of a given file path. In this case, it returns the directory that contains the `shark.txt` file: `ocean/animals/fish`.

`Path`实例上的`parent`属性返回给定文件路径的最直接祖先。 在这种情况下，它将返回包含`shark.txt`文件的目录： `ocean/animals/fish` 。

We can access the `parent` attribute multiple times in a row to traverse up the ancestry tree of a given file:

我们可以连续访问`parent`属性多次以遍历给定文件的祖先树：

shark = Path("ocean", "animals", "fish", "shark.txt")
    print(shark)
    print(shark.parent.parent)

If we run this code, we’ll receive the following output:

如果运行此代码，我们将收到以下输出：

Output ocean/animals/fish/shark.txt
    ocean/animals

The output is similar to the earlier output, but now we’ve traversed yet another level higher by accessing `.parent` a second time. Two directories up from `shark.txt` is the `ocean/animals` directory.

输出类似于先前的输出，但是现在我们通过第二次访问`.parent`遍历了另一个更高的层次。 `shark.txt`两个目录是`ocean/animals`目录。

## 使用Glob列出文件 **(**Using Glob to List Files**)** ##

It’s also possible to use the `Path` class to list files using the `glob` method.

也可以使用`Path`类通过`glob`方法列出文件。

Let’s say we had a directory structure that looked like this:

假设我们有一个看起来像这样的目录结构：

└── ocean
        ├── animals
        │   └── fish
        │       └── shark.txt
        ├── tides.txt
        └── wave.txt

An `ocean` directory contains the files `tides.txt` and `wave.txt`. We have a file named `shark.txt` nested under the `ocean` directory, an `animals` directory, and a `fish` directory: `ocean/animals/fish`.

`ocean`目录包含文件`tides.txt`和`wave.txt` 。 我们有一个名为`shark.txt`的文件，嵌套在`ocean`目录， `animals`目录和`fish`目录下： `ocean/animals/fish` 。

To list all the `.txt` files in the `ocean` directory, we could say:

要列出`ocean`目录中的所有`.txt`文件，我们可以说：

for txt_path in Path("ocean").glob("*.txt"):
        print(txt_path)

This code would yield output like:

此代码将产生如下输出：

Output ocean/wave.txt
    ocean/tides.txt

The `"*.txt"` [*glob pattern*][glob pattern] finds all files ending in `.txt`. Since the code sample executes that glob in the `ocean` directory, it returns the two `.txt` files in the `ocean` directory: `wave.txt` and `tides.txt`.

`"*.txt"` [*全局模式可*][glob pattern]找到所有以`.txt`结尾的文件。 由于代码示例执行该水珠在`ocean`的目录，它返回两个`.txt`的文件`ocean`目录： `wave.txt`和`tides.txt` 。

**Note:** If you would like to duplicate the outputs shown in this example, you’ll need to mimic the directory structure illustrated here on your computer.

**注意：**如果要复制此示例中显示的输出，则需要模拟计算机上此处所示的目录结构。

We can also use the `glob` method recursively. To list all the `.txt` files in the `ocean` directory and all its subdirectories, we could say:

我们还可以递归使用`glob`方法。 要列出`ocean`目录及其所有子目录中的所有`.txt`文件，我们可以说：

for txt_path in Path("ocean").glob("**/*.txt"):
        print(txt_path)

If we run this code, we’d receive output like the following:

如果运行此代码，我们将收到如下输出：

Output ocean/wave.txt
    ocean/tides.txt
    ocean/animals/fish/shark.txt

The `**` part of the glob pattern will match this directory and all directories beneath it, recursively. So, not only do we have the `wave.txt` and `tides.txt` files in the output, but we also receive the `shark.txt` file that was nested under `ocean/animals/fish`.

全局模式的`**`部分将递归匹配此目录及其下的所有目录。 因此，我们不仅在输出中包含`wave.txt`和`tides.txt`文件，而且还收到嵌套在`ocean/animals/fish`下的`shark.txt`文件。

## 计算相对路径 **(**Computing Relative Paths**)** ##

We can use the `Path.relative_to` method to compute paths relative to one another. The `relative_to` method is useful when, for example, you want to retrieve a portion of a long file path.

我们可以使用`Path.relative_to`方法来计算相对于彼此的路径。 例如，当您想要检索长文件路径的一部分时， `relative_to`方法很有用。

Consider the following code:

考虑以下代码：

shark = Path("ocean", "animals", "fish", "shark.txt")
    below_ocean = shark.relative_to(Path("ocean"))
    below_animals = shark.relative_to(Path("ocean", "animals"))
    print(shark)
    print(below_ocean)
    print(below_animals)

If we run this, we’ll receive output like the following:

如果运行此命令，则将收到类似以下的输出：

Output ocean/animals/fish/shark.txt
    animals/fish/shark.txt
    fish/shark.txt

The `relative_to` method returns a new `Path` object relative to the given argument. In our example, we compute the `Path` to `shark.txt` relative to the `ocean` directory, and then relative to both the `ocean` and `animals` directories.

`relative_to`方法返回相对于给定参数的新`Path`对象。 在我们的示例中，我们相对于`ocean`目录(然后相对于`ocean`目录和`animals`目录)计算`shark.txt`的`Path` 。

If `relative_to` can’t compute an answer because we give it an unrelated path, it raises a `ValueError`:

如果`relative_to`因为我们给它一个不相关的路径而无法计算答案，则会引发`ValueError` ：

shark = Path("ocean", "animals", "fish", "shark.txt")
    shark.relative_to(Path("unrelated", "path"))

We’ll receive a `ValueError` exception raised from this code that will be something like this:

我们将收到此代码引发的`ValueError`异常，如下所示：

Output Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/usr/local/lib/Python3.8/pathlib.py", line 899, in relative_to
        raise ValueError("{!r} does not start with {!r}"
    ValueError: 'ocean/animals/fish/shark.txt' does not start with 'unrelated/path'

`unrelated/path` is not a part of `ocean/animals/fish/shark.txt`, so there’s no way for Python to compute a relative path for us.

`unrelated/path`不是`ocean/animals/fish/shark.txt` ，因此Python无法为我们计算相对路径。

## 结论 **(**Conclusion**)** ##

The `pathlib` module is a powerful part of the [Python Standard Library][] that lets us manipulate filesystem paths quickly on any operating system. In this tutorial, we have learned to use some of `pathlib`’s key utilities for accessing file attributes, listing files with glob patterns, and traversing parent files and directories.

`pathlib`模块是[Python标准库][Python Standard Library]的强大功能，可让我们在任何操作系统上快速操作文件系统路径。 在本教程中，我们学习了使用`pathlib`的一些关键实用程序来访问文件属性，列出具有glob模式的文件以及遍历父文件和目录。

The `pathlib` module exposes additional classes and utilities that we did not cover in this tutorial. Now that you have a baseline, you can use [the `pathlib` module’s documentation][the _pathlib_ module] to learn more about other available classes and utilities.

`pathlib`模块公开了我们在本教程中未涵盖的其他类和实用程序。 有了基准后，就可以使用[`pathlib`模块的文档][the _pathlib_ module]来了解有关其他可用类和实用程序的更多信息。

If you’re interested in using other Python libraries, check out the following tutorials:

如果您对使用其他Python库感兴趣，请查看以下教程：

*  [How To Use the collections Module in Python 3][]
    
    [如何在Python 3中使用collections模块][How To Use the collections Module in Python 3]
 *  [How To Use the sqlite3 Module in Python 3][]
    
    [如何在Python 3中使用sqlite3模块][How To Use the sqlite3 Module in Python 3]
 *  [How To Use ThreadPoolExecutor in Python 3][]
    
    [如何在Python 3中使用ThreadPoolExecutor][How To Use ThreadPoolExecutor in Python 3]

> 翻译自: [https://www.digitalocean.com/community/tutorials/how-to-use-the-pathlib-module-to-manipulate-filesystem-paths-in-python-3][https_www.digitalocean.com_community_tutorials_how-to-use-the-pathlib-module-to-manipulate-filesystem-paths-in-python-3]

[COVID-19 Relief Fund]: https://www.brightfunds.org/funds/write-for-donations-covid-19-relief-fund
[Write for DOnations]: https://do.co/w4do-cta
[the _pathlib_ module]: https://docs.python.org/3/library/pathlib.html
[os.path_ module]: https://docs.python.org/3.7/library/os.path.html
[How To Code in Python 3]: https://www.digitalocean.com/community/tutorial_series/how-to-code-in-python-3
[classes]: https://www.digitalocean.com/community/tutorials/how-to-construct-classes-and-define-objects-in-python-3
[relative path]: https://en.wikipedia.org/wiki/Path_%28computing%29#Absolute_and_relative_paths
[glob pattern]: https://en.wikipedia.org/wiki/Glob_%28programming%29#:%7E:text=In%20computer%20programming%2C%20glob%20patterns,Unix%20Bash%20shell%20command%20mv%20*.&text=Here%2C%20*%20is%20a%20wildcard%20standing,which%20stands%20for%20one%20character.
[Python Standard Library]: https://docs.python.org/3/library/
[How To Use the collections Module in Python 3]: https://www.digitalocean.com/community/tutorials/how-to-use-the-collections-module-in-python-3
[How To Use the sqlite3 Module in Python 3]: https://www.digitalocean.com/community/tutorials/how-to-use-the-sqlite3-module-in-python-3
[How To Use ThreadPoolExecutor in Python 3]: https://www.digitalocean.com/community/tutorials/how-to-use-threadpoolexecutor-in-python-3
[https_www.digitalocean.com_community_tutorials_how-to-use-the-pathlib-module-to-manipulate-filesystem-paths-in-python-3]: https://www.digitalocean.com/community/tutorials/how-to-use-the-pathlib-module-to-manipulate-filesystem-paths-in-python-3