Walk (arcpy.da)

摘要

通过从上到下或从下到上遍历目录树，可在目录树中生成数据的名称。树中各字典/工作空间提供一个三元组：dirpath、dirnames 和 filenames。

讨论

注:

Walk 函数在 ArcGIS 10.1 Service Pack 1 中可用。

Python 的 os 模块包括 os.walk 函数，可用于遍历目录树并查找数据。os.walk 是基础文件，它不识别数据库内容，例如，地理数据库要素类、表或栅格。arcpy.da.Walk 可用于为数据编目录。

语法

Walk (top, {topdown}, {onerror}, {followlinks}, {datatype}, {type})

参数	说明	数据类型
top	The top-level workspace that will be used.	String
topdown	If topdown is True or not specified, the tuple for a directory is generated before the tuple for any of its workspaces (workspaces are generated top-down). If topdown is False, the tuple for a workspace is generated after the tuple for all of its subworkspaces (workspaces are generated bottom-up). When topdown is True, the dirnames list can be modified in-place, and Walk() will only recurse into the subworkspaces whose names remain in dirnames. This can be used to limit the search, impose a specific order of visiting, or even to inform Walk() about directories the caller creates or renames before it resumes Walk() again. Modifying dirnames when topdown is False is ineffective, because in bottom-up mode the workspaces in dirnames are generated before dirpath itself is generated. (默认值为 True)	Boolean
onerror	Errors are ignored by default. The onerror function will be called with an OSError instance. The function can be used to report the error and continue with the walk or raise an exception to abort. 注: The file name is available as the filename attribute of the exception object. (默认值为 None)	Function
followlinks	By default, Walk() does not walk into connection files. Set followlinks to True to visit connection files. (默认值为 False)	Boolean
datatype	The datatype to limit the results returned. Valid datatypes are: Any —All data types are returned. Equivalent to using None or skipping the argument. CadDrawing CadastralFabric Container FeatureClass FeatureDataset Geo GeometricNetwork LasDataset Layer Locator Map MosaicDataset PlanarGraph RasterBand RasterCatalog RasterDataset RelationshipClass RepresentationClass SchematicDataset Style Table Terrain Text Tin Tool Toolbox Topology Multiple datatypes are supported if entered as a list or tuple. for dirpath, dirnames, filenames in arcpy.da.Walk(workspace, datatype=['RasterBand', 'RasterDataset']): (默认值为 None)	String
type	Feature and raster data types can be further limited by type. ALL —All types are returned. Equivalent to using None or skipping the argument. ANY —All types are returned. Equivalent to using None or skipping the argument. Valid feature types are: Multipatch — Only multipatch feature classes are returned. Multipoint —Only multipoint feature classes are returned. Point —Only point feature classes are returned. Polygon —Only polygon feature classes are returned. Polyline —Only polyline feature classes are returned. Valid raster types are: BIL — Esri Band Interleaved by Line file BIP — Esri Band Interleaved by Pixel file BMP — Bitmap graphic raster dataset format BSQ — Esri Band Sequential file DAT — ENVI DAT file GIF — Graphic Interchange Format for raster datasets GRID — Esri Grid raster dataset format IMG — ERDAS IMAGINE raster data format JP2 — JPEG 2000 raster dataset format JPG — Joint Photographic Experts Group raster dataset format PNG — Portable Network Graphic raster dataset format TIF — Tag Image File Format for raster datasets Multiple datatypes are supported if entered as a list or tuple. for dirpath, dirnames, filenames in arcpy.da.Walk(workspace, datatype='FeatureClass', type=['Polygon', 'Polyline']): (默认值为 None)	String

返回值

数据类型	说明
Generator	提供的三元组包括工作空间、目录名称和文件名称（dirpath、dirnames 和 filenames）。 dirpath 是以字符串形式存在的工作空间路径。 dirnames 是子目录和 dirpath 中其他工作空间的名称列表。 filenames 是 dirpath 中非工作空间内容的名称列表。 注: 列表中的名称仅包括基本名称，不包括路径组件。为在 dirpath 中获得文件或目录的完整路径（始于顶级），请运行 os.path.join（dirpath，名称）。

代码实例

Walk 示例 1

使用 Walk 函数为面要素类创建目录。

import arcpy
import os
workspace = "c:/data"
feature_classes = []
for dirpath, dirnames, filenames in arcpy.da.Walk(workspace,
                                                  datatype="FeatureClass",
                                                  type="Polygon"):
    for filename in filenames:
        feature_classes.append(os.path.join(dirpath, filename))

Walk 示例 2

使用 Walk 函数为栅格数据创建目录。将忽略文件夹中所有名为 back_up 的栅格。

import arcpy
import os
workspace = "c:/data"
rasters = []
for dirpath, dirnames, filenames in arcpy.da.Walk(workspace,
                                                  topdown=True,
                                                  datatype="Raster"):
    # Disregard any folder named 'back_up' in creating list 
    #  of rasters
    if "back_up" in dirnames:
        dirnames.remove('back_up')
    for filename in filenames:
        rasters.append(os.path.join(dirpath, filename))