SpatialReference
Summary
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.
Discussion
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
XY, Z, and M extents are not the same as spatial reference domains. The XY, Z, and M domains in a spatial reference define the valid range of coordinate values that can be stored in a feature class. The feature class extents reflect the actual range of coordinate values that exist in the feature class. These extents cannot be larger than the domains.
The SpatialReference object supports equal (==) and not equal (!=) operators for comparing spatial references.
Note:
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.
Syntax
SpatialReference({item}, {vcs}, {text})
| Name | Explanation | Data type |
|---|---|---|
|
item (Optional) |
The horizontal coordinate system used to create the Create a
Create a
Create a Create a
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 (Optional) |
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: Define the vertical coordinate system using a name.
Define the vertical coordinate system using a factory code. |
Variant |
|
text (Optional) |
A well-known text (WKT or WKT2 format) string that can be used to define a horizontal and vertical coordinate system. Note:When creating a Create a Create a Create a |
String |
Properties
| Name | Explanation | Data type |
|---|---|---|
|
GCS (Read only) |
A projected coordinate system returns a |
SpatialReference |
|
MDomain (Read only) |
The extent of the measure domain. |
String |
|
MFalseOriginAndUnits (Read only) |
The measure false origin and units. |
String |
|
MResolution (Read and Write) |
The measure resolution. |
Double |
|
MTolerance (Read and Write) |
The measure tolerance. |
Double |
|
VCS (Read only) |
If the coordinate system has a vertical coordinate system, the property returns a |
Object |
|
XYResolution (Read and Write) |
The x,y-resolution. |
Double |
|
XYTolerance (Read and Write) |
The x,y-tolerance. |
Double |
|
ZDomain (Read only) |
The extent of the z-domain. |
String |
|
ZFalseOriginAndUnits (Read only) |
The z false origin and units. |
String |
|
ZResolution (Read and Write) |
The z-resolution. |
Double |
|
ZTolerance (Read and Write) |
The z-tolerance. |
Double |
|
abbreviation (Read and Write) |
The abbreviated name of the spatial reference. |
String |
|
alias (Read and Write) |
The alias of the spatial reference. |
String |
|
domain (Read only) |
The extent of the x,y-domain. |
String |
|
factoryCode (Read and Write) |
The factory code or well-known ID (WKID) of the spatial reference. |
Integer |
|
falseOriginAndUnits (Read only) |
The false origin and units. |
String |
|
hasMPrecision (Read only) |
Specifies whether m-value precision information has been defined. |
Boolean |
|
hasXYPrecision (Read only) |
Specifies whether x,y-coordinate precision information has been defined. |
Boolean |
|
hasZPrecision (Read only) |
Specifies whether z-value precision information has been defined. |
Boolean |
|
isHighPrecision (Read and Write) |
Specifies whether the spatial reference has high precision set. |
Boolean |
|
name (Read and Write) |
The name of the spatial reference. |
String |
|
remarks (Read and Write) |
The comment string of the spatial reference. |
String |
|
type (Read and Write) |
Specifies the type of the spatial reference.
|
String |
|
usage (Read only) |
The usage notes. |
String |
|
PCSCode (Read and Write) |
The projected coordinate system code.1 |
Integer |
|
PCSName (Read and Write) |
The projected coordinate system name.1 |
String |
|
azimuth (Read and Write) |
The azimuth of a projected coordinate system.1 |
Double |
|
centralMeridian (Read and Write) |
The central meridian of a projected coordinate system.1 |
Double |
|
centralMeridianInDegrees (Read and Write) |
The central meridian (Lambda0) of a projected coordinate system in degrees.1 |
Double |
|
centralParallel (Read and Write) |
The central parallel of a projected coordinate system.1 |
Double |
|
classification (Read only) |
The classification of a map projection.1 |
String |
|
falseEasting (Read and Write) |
The false easting of a projected coordinate system.1 |
Double |
|
falseNorthing (Read and Write) |
The false northing of a projected coordinate system.1 |
Double |
|
latitudeOf1st (Read and Write) |
The latitude of the first point of a projected coordinate system.1 |
Double |
|
latitudeOf2nd (Read and Write) |
The latitude of the second point of a projected coordinate system.1 |
Double |
|
latitudeOfOrigin (Read and Write) |
The latitude of origin of a projected coordinate system.1 |
Double |
|
linearUnitCode (Read and Write) |
The linear unit code.1 |
Integer |
|
linearUnitName (Read and Write) |
The linear unit name.1 |
String |
|
longitude (Read and Write) |
The longitude value of this prime meridian.1 |
Double |
|
longitudeOf1st (Read and Write) |
The longitude of the first point of a projected coordinate system.1 |
Double |
|
longitudeOf2nd (Read and Write) |
The longitude of the second point of a projected coordinate system.1 |
Double |
|
longitudeOfOrigin (Read and Write) |
The longitude of origin of a projected coordinate system.1 |
Double |
|
metersPerUnit (Read only) |
The meters per linear unit.1 |
Double |
|
projectionCode (Read and Write) |
The projection code.1 |
Integer |
|
projectionName (Read and Write) |
The projection name.1 |
String |
|
scaleFactor (Read and Write) |
The scale factor of a projected coordinate system.1 |
Double |
|
standardParallel1 (Read and Write) |
The first parallel of a projected coordinate system.1 |
Double |
|
standardParallel2 (Read and Write) |
The second parallel of a projected coordinate system.1 |
Double |
|
GCSCode (Read and Write) |
The geographic coordinate system code.2 |
Integer |
|
GCSName (Read and Write) |
The geographic coordinate system name.2 |
String |
|
angularUnitCode (Read and Write) |
The angular unit code.2 |
Integer |
|
angularUnitName (Read and Write) |
The angular unit name.2 |
String |
|
datumCode (Read and Write) |
The datum code.2 |
Integer |
|
datumName (Read and Write) |
The datum name.2 |
String |
|
flattening (Read and Write) |
The flattening ratio of this spheroid.2 |
Double |
|
longitude (Read and Write) |
The longitude value of this prime meridian.2 |
Double |
|
primeMeridianCode (Read and Write) |
The prime meridian code.2 |
Integer |
|
primeMeridianName (Read and Write) |
The prime meridian name.2 |
String |
|
radiansPerUnit (Read only) |
The radians per angular unit.2 |
Double |
|
semiMajorAxis (Read and Write) |
The semi-major axis length of this spheroid.2 |
Double |
|
semiMinorAxis (Read and Write) |
The semi-minor axis length of this spheroid.2 |
Double |
|
spheroidCode (Read and Write) |
The spheroid code.2 |
Integer |
|
spheroidName (Read and Write) |
The spheroid name.2 |
String |
Methods
create()
Creates the SpatialReference object using properties.
createFromFile(prj_file)
Creates the SpatialReference object from a projection file.
| Name | Explanation | Data type |
|---|---|---|
|
prj_file |
The projection file used to populate the |
String |
exportToString({encoding})
Exports the object to its string representation.
| Name | Explanation | Data type |
|---|---|---|
|
encoding (Optional) |
Specifies the encoding of the exported string.
The default value is WKT. |
String |
Return value
| Data type | Explanation |
|---|---|
|
String |
The WKT or WKT 2 representation of the object. |
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
VERTCSsection 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)
| Name | Explanation | Data type |
|---|---|---|
|
string |
The WKT string representation of the object. |
String |
setDomain(x_min, x_max, y_min, y_max)
Sets the x,y-domain.
| Name | Explanation | Data type |
|---|---|---|
|
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)
Sets the false x,y origin and units.
| Name | Explanation | Data type |
|---|---|---|
|
false_x |
The false x-value. |
Double |
|
false_y |
The false y-value. |
Double |
|
xy_units |
The x,y-units. |
String |
setMDomain(m_min, m_max)
Sets the m-domain.
| Name | Explanation | Data type |
|---|---|---|
|
m_min |
The minimum m-value. |
Double |
|
m_max |
The maximum m-value. |
Double |
setMFalseOriginAndUnits(false_m, m_units)
Sets the false m origin and units.
| Name | Explanation | Data type |
|---|---|---|
|
false_m |
The false m-value. |
Double |
|
m_units |
The m-units. |
Double |
setZDomain(z_min, z_max)
Sets the z-domain.
| Name | Explanation | Data type |
|---|---|---|
|
z_min |
The minimum z-value. |
Double |
|
z_max |
The maximum z-value. |
Double |
setZFalseOriginAndUnits(false_z, z_units)
Sets the false z origin and units.
| Name | Explanation | Data type |
|---|---|---|
|
false_z |
The false z-value. |
Double |
|
z_units |
The false z-units. |
Double |
Code sample
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(r"{fc} has an unknown spatial reference")
# Otherwise, print out the feature class name and spatial reference
else:
print(f"{fc} : {spatial_ref.name}")