ArcMap

ListTransformations

Resumen

Returns a list of valid transformation methods. An extent can be used to narrow down the list of valid transformation methods for a specific geographic area.

The most appropriate transformation is usually the first one in the returned list. The list is sorted by amount of overlap of the data versus the areas of use of the transformations. If two or more transformations have the same amount of overlap with the data, the transformation accuracy values are used as a secondary sort parameter.

For a list of transformations and their area of use, see the following knowledge base article: How To: Select the correct geographic (datum) transformation when projecting between datums.

Sintaxis

ListTransformations (from_sr, to_sr, {extent})
ParámetroExplicaciónTipo de datos
from_sr

The starting geographic coordinate system. Can be specified with a SpatialReference object, the name of the spatial reference, or a path to a projection file (.prj).

SpatialReference
to_sr

The final geographic coordinate system. Can be specified with a SpatialReference object, the name of the spatial reference, or a path to a projection file (.prj).

SpatialReference
extent

Only transformations that span the entire extent will be returned. The extent needs to be specified in coordinates from the in_sr. When working with data, the extent on a Describe object can be used.

Extent

Valor de retorno

Tipo de datosExplicación
String

A list of valid transformation methods.

Muestra de código

ListTransformations example

Use ListTransformations to identify valid transformations for projecting from one coordinate system to another.

import arcpy

from_sr = arcpy.SpatialReference('WGS 1984')
to_sr = arcpy.SpatialReference('NAD 1927 StatePlane California VI FIPS 0406')

extent = arcpy.Extent(-178.217598182, 18.9217863640001,
                      -66.969270909, 71.4062354550001)
transformations = arcpy.ListTransformations(from_sr, to_sr, extent)

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