Describe

Synthèse

Describes a data element and returns a Describe object with multiple properties, such as data type, fields, indexes, and many others. Its properties are dynamic, meaning that depending on the data type described, different describe properties will be available for use.

Describe properties are organized into a series of property groups. Any particular dataset will acquire the properties of at least one of these groups. For example, if describing a geodatabase feature class, you can access properties from the Geodatabase Feature Class, Feature Class, Table, and Dataset property groups. All data, regardless of the data type, will always acquire the generic Describe object properties.

Discussion

Many data types include properties from other property groups. For example, if describing a geodatabase feature class, you can access properties from the Geodatabase Feature Class, Feature Class, Table, and Dataset property groups.

See arcpy.da.Describe, which returns the same information but as a dictionary.

Remarque :

In some cases, the object returned by Describe will not have all of the properties that are documented for it. For example, the Describe object for a layer in a map will not have the layer property set. That property only exists if you describe a .lyr file.

If you try to access a property that a Describe object does not have, it will return either an error or an empty value (None, 0 or -1, or an empty string). If you are uncertain of a particular property, you can use the Python hasattr() function to check.

• Describe object properties
• ArcInfo Workstation Item properties
• ArcInfo Workstation Table properties
• Attribute Rule properties
• BIM File Workspace properties
• CAD Drawing Dataset properties
• CAD Feature Class properties
• Coverage Feature Class properties
• Coverage properties
• Dataset properties
• dBASE Table properties
• Editor Tracking properties
• Feature Class properties
• Field group properties
• File properties
• Folder properties
• Geodatabase Feature Class properties
• Geodatabase Table properties
• Geometric Network properties
• Geostatistical Layer properties
• LAS Dataset properties
• Layer properties
• Location Referencing Dataset properties
• Map Document properties
• Mosaic Dataset properties
• Network Analyst Layer properties
• Network Dataset properties
• Parcel Fabric properties
• Parcel Fabric For ArcMap properties
• Projection File properties
• Raster Band properties
• Raster Catalog properties
• Raster Dataset properties
• Record Set and Feature Set properties
• Relationship Class properties
• Representation Class properties
• Schematic Dataset properties
• Schematic Diagram properties
• Schematic Folder properties
• SDC Feature Class properties
• Shapefile Feature Class properties
• Table properties
• Table View properties
• Text File properties
• Tin properties
• Tool properties
• Toolbox properties
• Topology properties
• Trace Network properties
• Utility Network properties
• VPF Coverage properties
• VPF Feature Class properties
• VPF Table properties
• Workspace properties

Syntaxe

Describe (value, {datatype})

Paramètre	Explication	Type de données
value	The specified data element or geoprocessing object to describe.	String
datatype	The type of data. This is only necessary when naming conflicts exist, for example, if a geodatabase contains a feature dataset (FeatureDataset) and a feature class (FeatureClass) with the same name. In this case, the data type is used to clarify which dataset will be described. (La valeur par défaut est None)	String

Valeur renvoyée

Type de données	Explication
Describe	Returns an object with properties detailing the data element described. Some of the returned object's properties will contain literal values or objects.

Exemple de code

Describe properties example (stand-alone script)

The following stand-alone script displays layer and describe object properties from a layer set by a script parameter. The parameter can be set to either a layer file or a layer in a map.

import arcpy

# Get the layer as a parameter and describe it.
#
# The layer could be a layer in ArcMap (like "some_layer")
# Or, it could be a .lyr file (like "C:/data/some.lyr")
#
layerString = arcpy.GetParameterAsText(0)
desc = arcpy.Describe(layerString)

# Print selected layer and describe object properties
# 
print("Name: {}".format(desc.name))
if hasattr(desc, "layer"):
    print("Layer name: {}".format(desc.layer.name))
    print("Layer data source: {}".format(desc.layer.catalogPath))
    print(".lyr file: {}".format(desc.catalogPath))
else:
    print("Layer name: {}".format(desc.name))
    print("Layer data source: {}".format(desc.catalogPath))

if desc.FIDSet != '':
    print("Number of selected features: {}".format(len(desc.FIDSet.split(";"))))