Walk

Summary

Returns data names in directory and database structures by moving through the tree from the top down or the bottom up. Each directory or workspace yields a tuple of three: directory path, directory names, and file names.

Discussion

The os module includes an os.walk function that can be used to move through a directory tree and find data. The os.walk function is file based and does not recognize database content such as geodatabase feature classes, tables, or rasters. For better performance, it is recommended that you use os.walk for file-based formats. The arcpy.da.Walk function can be used to catalog data.

Syntax

Walk (top, {topdown}, {onerror}, {followlinks}, {datatype}, {type})
ParameterExplanationData Type
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 trom the top down). If topdown is False, the tuple for a workspace is generated after the tuple for all of its subworkspaces (workspaces are generated from the 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 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 is generated.

(The default value is True)

Boolean
onerror

Errors are ignored by default. The onerror function will be called with an OSError instance.

This function can be used to report the error and continue with Walk or raise an exception to cancel.

Note:

The file name is available as the filename attribute of the exception object.

(The default value is None)

Function
followlinks

By default, Walk does not visit connection files. Set followlinks to True to visit connection files.

(The default value is False)

Boolean
datatype

Specifies the data type that will be used to limit the results.

  • AnyAll data types are returned. This is equivalent to using None or skipping the argument.
  • CadDrawingCAD files (.dwg, .dxf, and .dgn) are returned.
  • FeatureClassFeature classes in a geodatabase and shapefiles (.shp) are returned.
  • FeatureDatasetFeature datasets in a geodatabase are returned.
  • GeometricNetworkGeometric networks in a geodatabase are returned.
  • LasDatasetLAS dataset files (.las and .lasd) are returned.
  • LayerLayer files (.lyrx) are returned.
  • LocatorLocator files (.loc) are returned.
  • Map ArcGIS Pro projects (.aprx files), ArcGIS Pro map documents (.mapx files), and ArcMap documents (.mxd files) are returned.
  • MosaicDatasetMosaic datasets in a geodatabase are returned.
  • NetworkDatasetNetwork datasets in a geodatabase are returned.
  • ParcelDatasetParcel fabric datasets are returned.
  • RasterCatalogRaster catalogs in a geodatabase are returned.
  • RasterDatasetRaster datasets in a geodatabase or in a folder are returned.
  • RelationshipClassRelationship classes in a geodatabase are returned.
  • RepresentationClassRepresentation classes in a geodatabase are returned.
  • TableTables in a geodatabase or folder and sheets in Excel workbooks are returned.
  • TerrainTerrain datasets are returned.
  • TinTIN surfaces in a geodatabase are returned.
  • ToolTools in a toolbox are returned.
  • TopologyTopologies in a geodatabase are returned.
  • UtilityNetworkUtility networks in a geodatabase are returned.

Multiple data types are supported if they're entered as a list or tuple.

for dirpath, dirnames, filenames in arcpy.da.Walk(workspace,
    datatype=['MosaicDataset', 'RasterDataset']):

(The default value is None)

String
type

Specifies whether feature and raster data types will be further limited by type.

  • AllAll types are returned. This is equivalent to using None or skipping the argument.
  • AnyAll types are returned. This is equivalent to using None or skipping the argument.

Valid feature types are the following:

  • MultipatchMultipatch feature classes are returned.
  • MultipointMultipoint feature classes are returned.
  • PointPoint feature classes are returned.
  • PolygonPolygon feature classes are returned.
  • PolylinePolyline feature classes are returned.

Valid raster types are the following:

  • 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 data types are supported if they're entered as a list or tuple.

for dirpath, dirnames, filenames in arcpy.da.Walk(workspace,
    datatype='FeatureClass', type=['Polygon', 'Polyline']):

(The default value is None)

String
Return Value
Data TypeExplanation
Generator

Yields a tuple of three that includes the workspace, directory names, and file names.

  • dirpath is the path to the workspace as a string.
  • dirnames is a list of names of subdirectories and other workspaces in dirpath.
  • filenames is a list of names of nonworkspace contents in dirpath.
Note:

Names in the lists include only the base name; no path components are included. For a full path (which begins with top) to a file or directory in dirpath, use os.path.join(dirpath, name).

Code sample

Walk example 1

Use the Walk function to catalog polygon feature classes in the workspace.

The code will include polygon feature classes in any feature datasets in a file geodatabase.

import arcpy
import os

workspace = "c:/data"
feature_classes = []

walk = arcpy.da.Walk(workspace, datatype="FeatureClass", type="Polygon")

for dirpath, dirnames, filenames in walk:
    for filename in filenames:
        feature_classes.append(os.path.join(dirpath, filename))
Walk example 2

Use the Walk function to catalog raster data. Any rasters in a folder named back_up will be ignored.

import arcpy
import os

workspace = "c:/data"
rasters = []

walk = arcpy.da.Walk(workspace, topdown=True, datatype="RasterDataset")

for dirpath, dirnames, filenames in walk:
    # 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))

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