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SpatialReference

En este tema

  1. Resumen
  2. Debate
  3. Sintaxis
  4. Propiedades
  5. Descripción general del método
  6. Métodos
  7. Muestra de código
Temas relacionados
  1. Use classes in Python
  2. Utilizar la clase de referencia espacial

Resumen

Each part of the spatial reference has a number of properties (especially the coordinate system) that defines what map projection options are used to define horizontal coordinates.

Debate

A SpatialReference object can also be accessed from existing datasets using the Describe spatialReference property.

dataset = "c:/data/landbase.gdb/Wetlands"
spatial_ref = arcpy.Describe(dataset).spatialReference

Las extensiones XY, Z y M no son las mismas que los dominios de referencia espacial. Los dominios XY, Z y M de una referencia espacial definen el rango válido de valores de coordenadas que se pueden almacenar en una clase de entidad. Las extensiones de la clase de entidad reflejan el rango real de valores de coordenadas que existen dentro de la clase de entidad. Estas extensiones no pueden ser más grandes que los dominios.

The SpatialReference object supports equal (==) and not equal (!=) operators for comparing spatial references.

Nota:

The spatial reference properties available depend on the coordinate system used. In the properties list below, those properties that are only available with a projected coordinate system are denoted with a 1; properties only available with a geographic coordinate system are denoted with a 2.

Because a projected coordinate system is based on a geographic coordinate system, projected coordinate system properties can be accessed from a geographic coordinate system using the GCS property.

Sintaxis

 SpatialReference ({item}, {vcs}, text)
ParámetroExplicaciónTipo de datos
item

The horizontal coordinate system used to create the SpatialReference. The coordinate system can be set using a projection file, name, or factory code.

  • Using the display name of the coordinate system
    sr = arcpy.SpatialReference("Sinusoidal (world)")
  • Using the canonical name of the coordinate system
    sr = arcpy.SpatialReference("World_Sinusoidal")
  • Using a coordinate system's factory code (or authority code or WKID)
    # The factory code of 32145 represents: 
# NAD 1983 StatePlane Vermont FIPS 4400 (Meters)

sr = arcpy.SpatialReference(32145)
  • Using a projection file (.prj)
    sr = arcpy.SpatialReference("c:/coordsystems/NAD 1983.prj")

For more information about coordinate system names and factory codes, see the geographic_coordinate_systems.pdf and projected_coordinate_systems.pdf files.

For more information, see Using the spatial reference class.

Variant
vcs

The vertical coordinate system (VCS). The VCS defines information about the z-coordinates, and can be set using a name or factory code. See the following examples:

  • Using a name
    sr = arcpy.SpatialReference("Hawaii Albers Equal Area Conic", "MSL Height")
  • Using a factory code
    
# Spatial Reference factory code of 32145 is : NAD 1983 StatePlane Vermont FIPS 4400 (Meters)
# Spatial Reference factory code of 5714 is : Mean Sea Level (Height)

sr = arcpy.SpatialReference(32145, 5714)
Variant
text

A well-known text (WKT) string that can be used to define a horizontal and vertical coordinate system.

  • Using a WKT string with a horizontal coordinate system
    # String below is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326)
wkt = "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],\
              PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]];\
              -400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;\
              0.001;0.001;IsHighPrecision"

sr = arcpy.SpatialReference(text=wkt)
  • Using a WKT string with a horizontal and vertical coordinate system. Note that the vcs argument is not used, and the vertical coordinate system is defined in the VERTCS section of the WKT.
    # The following string is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326)
wkt = "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],\
              PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],\
              VERTCS['WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],\
              PARAMETER['Vertical_Shift',0.0],PARAMETER['Direction',1.0],UNIT['Meter',1.0]];\
              -400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;\
              0.001;0.001;IsHighPrecision"

sr = arcpy.SpatialReference(text=wkt)
String

Propiedades

PropiedadExplicaciónTipo de datos
GCS
(Sólo lectura)

A projected coordinate system returns a SpatialReference object for the geographic coordinate system it is based on. A geographic coordinate system returns the same SpatialReference.

SpatialReference
MDomain
(Sólo lectura)

The extent of the measure domain.

String
MFalseOriginAndUnits
(Sólo lectura)

The measure false origin and units.

String
MResolution
(Lectura y escritura)

The measure resolution.

Double
MTolerance
(Lectura y escritura)

The measure tolerance.

Double
VCS
(Sólo lectura)

If the coordinate system has a vertical coordinate system, it returns a VCS object for the vertical coordinate system it is based on.

Object
XYResolution
(Lectura y escritura)

The xy resolution.

Double
XYTolerance
(Lectura y escritura)

The xy tolerance.

Double
ZDomain
(Sólo lectura)

The extent of the z domain.

String
ZFalseOriginAndUnits
(Sólo lectura)

The z false origin and units.

String
ZResolution
(Lectura y escritura)

The z resolution property.

Double
ZTolerance
(Lectura y escritura)

The z-tolerance property.

Double
abbreviation
(Lectura y escritura)

The abbreviated name of the spatial reference.

String
alias
(Lectura y escritura)

The alias of the spatial reference.

String
domain
(Sólo lectura)

The extent of the xy domain.

String
factoryCode
(Lectura y escritura)

The factory code or well-known ID (WKID) of the spatial reference.

Integer
falseOriginAndUnits
(Sólo lectura)

The false origin and units.

String
hasMPrecision
(Sólo lectura)

Indicates whether m-value precision information has been defined.

Boolean
hasXYPrecision
(Sólo lectura)

Indicates whether xy precision information has been defined.

Boolean
hasZPrecision
(Sólo lectura)

Indicates whether z-value precision information has been defined.

Boolean
isHighPrecision
(Lectura y escritura)

Indicates whether the spatial reference has high precision set.

Boolean
name
(Lectura y escritura)

The name of the spatial reference.

String
remarks
(Lectura y escritura)

The comment string of the spatial reference.

String
type
(Lectura y escritura)

The type of the spatial reference.

  • Geographic—A geographic coordinate system.
  • Projected— A projected coordinate system.
String
usage
(Sólo lectura)

The usage notes.

String
PCSCode
(Lectura y escritura)

The projected coordinate system code.1

Integer
PCSName
(Lectura y escritura)

The projected coordinate system name.1

String
azimuth
(Lectura y escritura)

The azimuth of a projected coordinate system.1

Double
centralMeridian
(Lectura y escritura)

The central meridian of a projected coordinate system.1

Double
centralMeridianInDegrees
(Lectura y escritura)

The central meridian (Lambda0) of a projected coordinate system in degrees.1

Double
centralParallel
(Lectura y escritura)

The central parallel of a projected coordinate system.1

Double
classification
(Sólo lectura)

The classification of a map projection.1

String
falseEasting
(Lectura y escritura)

The false easting of a projected coordinate system.1

Double
falseNorthing
(Lectura y escritura)

The false northing of a projected coordinate system.1

Double
latitudeOf1st
(Lectura y escritura)

The latitude of the first point of a projected coordinate system.1

Double
latitudeOf2nd
(Lectura y escritura)

The latitude of the second point of a projected coordinate system.1

Double
latitudeOfOrigin
(Lectura y escritura)

The latitude of origin of a projected coordinate system.1

Double
linearUnitCode
(Lectura y escritura)

The linear unit code.1

Integer
linearUnitName
(Lectura y escritura)

The linear unit name.1

String
longitude
(Lectura y escritura)

The longitude value of this prime meridian.1

Double
longitudeOf1st
(Lectura y escritura)

The longitude of the first point of a projected coordinate system.1

Double
longitudeOf2nd
(Lectura y escritura)

The longitude of the second point of a projected coordinate system.1

Double
longitudeOfOrigin
(Lectura y escritura)

The longitude of origin of a projected coordinate system.1

Double
metersPerUnit
(Sólo lectura)

The meters per linear unit.1

Double
projectionCode
(Lectura y escritura)

The projection code.1

Integer
projectionName
(Lectura y escritura)

The projection name.1

String
scaleFactor
(Lectura y escritura)

The scale factor of a projected coordinate system.1

Double
standardParallel1
(Lectura y escritura)

The first parallel of a projected coordinate system.1

Double
standardParallel2
(Lectura y escritura)

The second parallel of a projected coordinate system.1

Double
GCSCode
(Lectura y escritura)

The geographic coordinate system code.2

Integer
GCSName
(Lectura y escritura)

The geographic coordinate system name.2

String
angularUnitCode
(Lectura y escritura)

The angular unit code.2

Integer
angularUnitName
(Lectura y escritura)

The angular unit name.2

String
datumCode
(Lectura y escritura)

The datum code.2

Integer
datumName
(Lectura y escritura)

The datum name.2

String
flattening
(Lectura y escritura)

The flattening ratio of this spheroid.2

Double
longitude
(Lectura y escritura)

The longitude value of this prime meridian.2

Double
primeMeridianCode
(Lectura y escritura)

The prime meridian code.2

Integer
primeMeridianName
(Lectura y escritura)

The prime meridian name.2

String
radiansPerUnit
(Sólo lectura)

The radians per angular unit.2

Double
semiMajorAxis
(Lectura y escritura)

The semi-major axis length of this spheroid.2

Double
semiMinorAxis
(Lectura y escritura)

The semi-minor axis length of this spheroid.2

Double
spheroidCode
(Lectura y escritura)

The spheroid code.2

Integer
spheroidName
(Lectura y escritura)

The spheroid name.2

String

Descripción general del método

MétodoExplicación
create ()

Creates the SpatialReference object using properties.

createFromFile (prj_file)

Creates the SpatialReference object from a projection file.

exportToString ()

Exports the object to its string representation.

loadFromString (string)

Defines a SpatialReference object from a WKT string.

The exportToString method can be used to export a WKT string representation of the spatial reference.

  • Using a WKT string with a horizontal coordinate system.
    # The following string is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326)
wkt = 'GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],\
              PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]];\
              -400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;\
              0.001;0.001;IsHighPrecision'

sr = arcpy.SpatialReference()
sr.loadFromString(wkt)
  • Using a WKT string with a horizontal and vertical coordinate system. Note that the vertical coordinate system is defined in the VERTCS section of the WKT.
    # The following string is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326), 
# with a vertical coordinate system "WGS 1984" (factory code=115700)

wkt = 'GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],\
              PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],\
              VERTCS["WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],\
              PARAMETER["Vertical_Shift",0.0],PARAMETER["Direction",1.0],UNIT["Meter",1.0]];\
              -400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;\
              0.001;0.001;IsHighPrecision'

sr = arcpy.SpatialReference()
sr.loadFromString(wkt)

setDomain (x_min, x_max, y_min, y_max)

Sets the XY domain.

setFalseOriginAndUnits (false_x, false_y, xy_units)

Sets the XY false origin and units.

setMDomain (m_min, m_max)

Sets the M domain.

setMFalseOriginAndUnits (false_m, m_units)

Sets the M false origin and units.

setZDomain (z_min, z_max)

Sets the Z domain.

setZFalseOriginAndUnits (false_z, z_units)

Sets the Z false origin and units.

Métodos

create ()
createFromFile (prj_file)
ParámetroExplicaciónTipo de datos
prj_file

The projection file used to populate the SpatialReference object.

String
exportToString ()
Valor de retorno
Tipo de datosExplicación
String

The WKT string representation of the object. 

loadFromString (string)
ParámetroExplicaciónTipo de datos
string

The WKT string representation of the object.

String
setDomain (x_min, x_max, y_min, y_max)
ParámetroExplicaciónTipo de datos
x_min

The minimum x-value.

Double
x_max

The maximum x-value.

Double
y_min

The minimum y-value.

Double
y_max

The maximum y-value.

Double
setFalseOriginAndUnits (false_x, false_y, xy_units)
ParámetroExplicaciónTipo de datos
false_x

The false x value.

Double
false_y

The false y value.

Double
xy_units

The xy units.

String
setMDomain (m_min, m_max)
ParámetroExplicaciónTipo de datos
m_min

The minimum m-value.

Double
m_max

The maximum m-value.

Double
setMFalseOriginAndUnits (false_m, m_units)
ParámetroExplicaciónTipo de datos
false_m

The false m-value.

Double
m_units

The m units.

Double
setZDomain (z_min, z_max)
ParámetroExplicaciónTipo de datos
z_min

The minimum z-value.

Double
z_max

The maximum z-value.

Double
setZFalseOriginAndUnits (false_z, z_units)
ParámetroExplicaciónTipo de datos
false_z

The false z-value.

Double
z_units

The false z units.

Double

Muestra de código

SpatialReference example

For each feature class in a workspace, print the name of its spatial reference.

import arcpy

# Set the workspace environment
arcpy.env.workspace = "c:/base/base.gdb"

# Get a list of the feature classes in the input folder
feature_classes = arcpy.ListFeatureClasses()

# Loop through the list
for fc in feature_classes:
    # Create the spatial reference object
    spatial_ref = arcpy.Describe(fc).spatialReference

    # If the spatial reference is unknown
    if spatial_ref.name == "Unknown":
        print("{} has an unknown spatial reference".format(fc))

    # Otherwise, print out the feature class name and spatial reference
    else:
        print("{} : {}".format(fc, spatial_ref.name))

Temas relacionados

  • Use classes in Python
  • Utilizar la clase de referencia espacial

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En este tema
  1. Resumen
  2. Debate
  3. Sintaxis
  4. Propiedades
  5. Descripción general del método
  6. Métodos
  7. Muestra de código
Temas relacionados
  1. Use classes in Python
  2. Utilizar la clase de referencia espacial