报错解决：pandas的依赖项openpyxl

问题：

使用pandas包，没有使用openpyxl包，但是报错：ImportError: Missing optional dependency openpyxl. Use pip or conda to install openpyxl.

翻译：缺少可选择的依赖项“openpyxl”，使用 pip install openpyxl or conda install openpyxl

解决方法：

首先，激活你的项目环境：activate “name of your project” 然后，安装openpyxl包：pip install openpyxl 注：直接安装到conda环境下：conda install openpyxl

此时，已经解决了遇到的问题，但是为什么呢，我们一起来分析pandas中的部分涉及openpyxl的文件的源码：

（1）pandas中的_openpyxl.py文件

类 OpenpyxlReader，说明了 pandas 在读取 xls 文件时，使用 openpyxl 引擎的阅读器（Reader using openpyxl engine）。

（2）pandas中的_optional.py文件

导入一个可以选择的依赖项。默认情况下，如果依赖项丢失，将引发带有好消息的 ImportError。 如果存在依赖项，但太旧，我们会提出。

def import_optional_dependency(
    name: str,
    extra: str = "",
    errors: str = "raise",
    min_version: str | None = None,
):
    """
    Import an optional dependency.

    By default, if a dependency is missing an ImportError with a nice
    message will be raised. If a dependency is present, but too old,
    we raise.

    Parameters
    ----------
    name : str
        The module name.
    extra : str
        Additional text to include in the ImportError message.
    errors : str {raise, warn, ignore}
        What to do when a dependency is not found or its version is too old.

        * raise : Raise an ImportError
        * warn : Only applicable when a modules version is to old.
          Warns that the version is too old and returns None
        * ignore: If the module is not installed, return None, otherwise,
          return the module, even if the version is too old.
          Its expected that users validate the version locally when
          using ``errors="ignore"`` (see. ``io/html.py``)
    min_version : str, default None
        Specify a minimum version that is different from the global pandas
        minimum version required.
    Returns
    -------
    maybe_module : Optional[ModuleType]
        The imported module, when found and the version is correct.
        None is returned when the package is not found and `errors`
        is False, or when the packages version is too old and `errors`
        is ``warn``.
    """

    assert errors in {"warn", "raise", "ignore"}

    package_name = INSTALL_MAPPING.get(name)
    install_name = package_name if package_name is not None else name

    msg = (
        f"Missing optional dependency {install_name}. {extra} "
        f"Use pip or conda to install {install_name}."
    )
    try:
        module = importlib.import_module(name)
    except ImportError:
        if errors == "raise":
            raise ImportError(msg) from None
        else:
            return None

    # Handle submodules: if we have submodule, grab parent module from sys.modules
    parent = name.split(".")[0]
    if parent != name:
        install_name = parent
        module_to_get = sys.modules[install_name]
    else:
        module_to_get = module
    minimum_version = min_version if min_version is not None else VERSIONS.get(parent)
    if minimum_version:
        version = get_version(module_to_get)
        if Version(version) < Version(minimum_version):
            msg = (
                f"Pandas requires version {minimum_version} or newer of {parent} "
                f"(version {version} currently installed)."
            )
            if errors == "warn":
                warnings.warn(msg, UserWarning)
                return None
            elif errors == "raise":
                raise ImportError(msg)

    return module

其中，报错的信息来自下面这四行代码，显示我们没有可选择的依赖项“openpyxl”，下载即可。

msg = (
        f"Missing optional dependency {install_name}. {extra} "
        f"Use pip or conda to install {install_name}."
    )

感悟：利用 python 对 Excal 表格进行增删查改对办公效率的提高有很大的帮助，本人习惯利用 pandas 和 xlswriter 对表格的读取、修改和保存。

>>>如有疑问，欢迎评论区一起探讨。