如何将参数传递给 Python 模块中的主函数？

Posted 2023-03-07

【中文标题】如何将参数传递给 Python 模块中的主函数？

【英文标题】：How to pass arguments to main function within Python module?

【发布时间】：2017-08-02 12:21:40

【问题描述】：

我最近开始了解有关 Python 包和模块的更多信息。我目前正忙于更新我现有的模块，以便可以作为脚本运行或作为模块导入到我的其他代码中。我不确定如何在模块中构造输入参数并将它们传递给模块中的 main() 函数。

我已经编写了我的 ma​​in() 函数并在 if __name__ == '__main__' 下调用它并传递输入参数。输入当前是硬编码的，以显示我想要实现的目标。对于如何正确构造用户将传递的输入参数，然后将其传递给主函数的任何帮助，我们将不胜感激。

如上所述，当直接使用或作为模块导入我的其他代码并从那里运行时，我试图能够将以下内容用作脚本。如果我将它作为模块导入，我会在导入时调用 ma​​in() 函数吗？以下结构在我编写以下内容时是否正确？任何建议表示赞赏。

'''
Created on March 12, 2017

Create a new ArcHydro Schema

File Geodatabase and Rasters

Folder

@author: PeterW
'''
# import site-packages and modules
import re
from pathlib import Path
import arcpy

# set environment settings
arcpy.env.overwriteOutput = True


def archydro_rasters_folder(workspace):
    """Create rasters folder directory
    if it doens't already exist"""
    model_name = Path(workspace).name
    layers_name = re.sub(r"\D+", "Layers", model_name)
    layers_folder = Path(workspace, layers_name)
    if layers_folder.exists():
        arcpy.AddMessage("Rasters folder: 0 exists".format(layers_name))
    else:
        layers_folder.mkdir(parents=True)
        arcpy.AddMessage("Rasters folder 0 created".format(layers_name))


def archydro_fgdb_schema(workspace, schema, dem):
    """Create file geodatabase using XML
    schema and set coordinate system based
    on input DEM if it doesn't already exist"""
    model_name = Path(workspace).name
    fgdb = "0.gdb".format(model_name)
    if arcpy.Exists(str(Path(workspace, fgdb))):
        arcpy.AddMessage("0 file geodatabase exists".format(fgdb))
    else:
        new_fgdb = arcpy.CreateFileGDB_management(str(workspace), fgdb)
        import_type = "SCHEMA_ONLY"
        config_keyword = "DEFAULTS"
        arcpy.AddMessage("New 0 file geodatabase created".format(fgdb))
        arcpy.ImportXMLWorkspaceDocument_management(new_fgdb, schema,
                                                    import_type,
                                                    config_keyword)
        arcpy.AddMessage("ArcHydro schema imported")
        projection = arcpy.Describe(dem).spatialReference
        projection_name = projection.PCSName
        feature_dataset = Path(workspace, fgdb, "Layers")
        arcpy.DefineProjection_management(str(feature_dataset),
                                          projection)
        arcpy.AddMessage("Changed projection to 0".format(projection_name))


def main(workspace, dem, schema):
    """main function to create rasters folder
    and file geodatabase"""
    archydro_rasters_folder(workspace)
    archydro_fgdb_schema(schema, dem, workspace)

if __name__ == '__main__':
    main(workspace = r"E:\Projects\2016\01_Bertrand_Small_Projects\G113268\ArcHydro\Model04",
         dem = r"E:\Projects\2016\01_Bertrand_Small_Projects\G113268\ArcHydro\DEM2\raw",
         schema = r"E:\Python\Masters\Schema\ESRI_UC12\ModelBuilder\Schema\Model01.xml")

更新日期：13 年 3 月 17 日

以下是我根据乔纳森的建议更新的 Python 模块：

'''
Created on March 12, 2017

Create a new ArcHydro Schema

File Geodatabase and Rasters

Folder

@author: PeterW
'''
# import site-packages and modules
import re
from pathlib import Path
import arcpy
import argparse

# set environment settings
arcpy.env.overwriteOutput = True


def rasters_directory(workspace):
    """Create rasters folder directory
    if it doens't already exist"""
    model_name = Path(workspace).name
    layers_name = re.sub(r"\D+", "Layers", model_name)
    layers_folder = Path(workspace, layers_name)
    if layers_folder.exists():
        arcpy.AddMessage("Rasters folder: 0 exists".format(layers_name))
    else:
        layers_folder.mkdir(parents=True)
        arcpy.AddMessage("Rasters folder 0 created".format(layers_name))


def fgdb_schema(workspace, schema, dem):
    """Create file geodatabase using XML
    schema and set coordinate system based
    on input DEM if it doesn't already exist"""
    model_name = Path(workspace).name
    fgdb = "0.gdb".format(model_name)
    if arcpy.Exists(str(Path(workspace, fgdb))):
        arcpy.AddMessage("0 file geodatabase exists".format(fgdb))
    else:
        new_fgdb = arcpy.CreateFileGDB_management(str(workspace), fgdb)
        import_type = "SCHEMA_ONLY"
        config_keyword = "DEFAULTS"
        arcpy.AddMessage("New 0 file geodatabase created".format(fgdb))
        arcpy.ImportXMLWorkspaceDocument_management(new_fgdb, schema,
                                                    import_type,
                                                    config_keyword)
        arcpy.AddMessage("ArcHydro schema imported")
        projection = arcpy.Describe(dem).spatialReference
        projection_name = projection.PCSName
        feature_dataset = Path(workspace, fgdb, "Layers")
        arcpy.DefineProjection_management(str(feature_dataset),
                                          projection)
        arcpy.AddMessage("Changed projection to 0".format(projection_name))


def model_schema(workspace, schema, dem):
    """Create model schema: rasters folder
    and file geodatabase"""
    rasters_directory(workspace)
    fgdb_schema(schema, dem, workspace)


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Create a ArcHydro schema')
    parser.add_argument('--workspace', metavar='path', required=True,
                        help='the path to workspace')
    parser.add_argument('--schema', metavar='path', required=True,
                        help='path to schema')
    parser.add_argument('--dem', metavar='path', required=True,
                        help='path to dem')
    args = parser.parse_args()
    model_schema(workspace=args.workspace, schema=args.schema, dem=args.dem)

【参考方案1】：

这对我来说是正确的，是的，如果您希望将其用作模块，则可以导入 main.不过，以更具描述性的方式命名它可能会更好。

阐明__main__ 和函数main() 的工作原理。当您执行一个模块时，它将有一个存储在__name__ 中的名称。如果您将模块作为脚本单独执行，它将具有名称__main__。如果您将它作为模块的一部分执行，即将它导入另一个模块，它将具有模块的名称。

函数main() 可以任意命名，这不会影响您的程序。它通常在小脚本中命名为main，但如果它是较大代码体的一部分，它就不是一个特别好的名字。

就让用户在作为脚本运行时输入参数而言，我会考虑使用argparse 或click

argparse 如何工作的示例。

if __name__ == '__main__':
    import argparse

    parser = argparse.ArgumentParser(description='Create a ArcHydro schema')
    parser.add_argument('--workspace', metavar='path', required=True,
                        help='the path to workspace')
    parser.add_argument('--schema', metavar='path', required=True,
                        help='path to schema')
    parser.add_argument('--dem', metavar='path', required=True,
                        help='path to dem')
    args = parser.parse_args()
    main(workspace=args.workspace, schema=args.schema, dem=args.dem)

【讨论】：

您好乔纳森，感谢以下内容。所以我的 main() 函数不必叫 main？

不，你可以随意称呼它。我更新了答案以包含更多细节:)

嗨乔纳森，你能给我一个例子，如何使用 argparse 将参数传递给我的 main() 函数。询问的原因是我在 main() 函数中调用了两个使用参数工作区的函数。

我已经更新了答案，包括如何使用 argparse。

嗨乔纳森，我非常感谢你，你帮了大忙。以下内容将极大地帮助我推进我的代码。