Transformer

The pyproj.Transformer has the capabilities of performing 2D, 3D, and 4D (time) transformations. It can do anything that the PROJ command line programs proj <https://proj.org/apps/proj.html>, cs2cs <https://proj.org/apps/cs2cs.html>, and cct <https://proj.org/apps/cct.html> can do. This means that it allows translation between any pair of definable coordinate systems, including support for datum transformation.

Warning

The axis order may be swapped if the source and destination CRS’s are defined as having the first coordinate component point in a northerly direction (See PROJ FAQ on axis order). You can check the axis order with the pyproj.CRS class. If you prefer to keep your axis order as always x,y, you can use the always_xy option when creating the Transformer.

pyproj.Transformer

class pyproj.transformer.Transformer(base_transformer=None)[source]

The Transformer class is for facilitating re-using transforms without needing to re-create them. The goal is to make repeated transforms faster.

Additionally, it provides multiple methods for initialization.

accuracy

Expected accuracy of the transformation. -1 if unknown.

Type

float

definition

Definition of the projection.

Type

str

description

Description of the projection.

Type

str

static from_crs(crs_from, crs_to, skip_equivalent=False, always_xy=False)[source]

Make a Transformer from a CRS or input used to create one.

Parameters

  • crs_from (CRS or input used to create one) – Projection of input data.

  • crs_to (CRS or input used to create one) – Projection of output data.

  • skip_equivalent (bool, optional) – If true, will skip the transformation operation if input and output projections are equivalent. Default is false.

  • always_xy (bool, optional) – If true, the transform method will accept as input and return as output coordinates using the traditional GIS order, that is longitude, latitude for geographic CRS and easting, northing for most projected CRS. Default is false.

Returns

Return type

Transformer

static from_pipeline(proj_pipeline)[source]

Make a Transformer from a PROJ pipeline string.

https://proj.org/operations/pipeline.html

Parameters

proj_pipeline (str) – Projection pipeline string.

Returns

Return type

~Transformer

static from_proj(proj_from, proj_to, skip_equivalent=False, always_xy=False)[source]

Make a Transformer from a Proj or input used to create one.

Parameters

  • proj_from (Proj or input used to create one) – Projection of input data.

  • proj_to (Proj or input used to create one) – Projection of output data.

  • skip_equivalent (bool, optional) – If true, will skip the transformation operation if input and output projections are equivalent. Default is false.

  • always_xy (bool, optional) – If true, the transform method will accept as input and return as output coordinates using the traditional GIS order, that is longitude, latitude for geographic CRS and easting, northing for most projected CRS. Default is false.

Returns

Return type

Transformer

has_inverse

True if an inverse mapping exists.

Type

bool

itransform(points, switch=False, time_3rd=False, radians=False, errcheck=False, direction=<TransformDirection.FORWARD: 'FORWARD'>)[source]

Iterator/generator version of the function pyproj.Transformer.transform.

Parameters

  • points (list) – List of point tuples.

  • switch (boolean, optional) – If True x, y or lon,lat coordinates of points are switched to y, x or lat, lon. Default is False.

  • time_3rd (boolean, optional) – If the input coordinates are 3 dimensional and the 3rd dimension is time.

  • radians (boolean, optional) – If True, will expect input data to be in radians and will return radians if the projection is geographic. Default is False (degrees). Ignored for pipeline transformations.

  • errcheck (boolean, optional (default False)) – If True an exception is raised if the transformation is invalid. By default errcheck=False and an invalid transformation returns inf and no exception is raised.

  • direction (TransformDirection, optional) – The direction of the transform. Default is FORWARD.

Example:

>>> from pyproj import Transformer
>>> transformer = Transformer.from_crs(4326, 2100)
>>> points = [(22.95, 40.63), (22.81, 40.53), (23.51, 40.86)]
>>> for pt in transformer.itransform(points): '{:.3f} {:.3f}'.format(*pt)
'2221638.801 2637034.372'
'2212924.125 2619851.898'
'2238294.779 2703763.736'
>>> pipeline_str = "+proj=pipeline +step +proj=longlat +ellps=WGS84 +step +proj=unitconvert +xy_in=rad +xy_out=deg"
>>> pipe_trans = Transformer.from_pipeline(pipeline_str)
>>> for pt in pipe_trans.itransform([(2.1, 0.001)]): '{:.3f} {:.3f}'.format(*pt)
'120.321 0.057'
>>> transproj = Transformer.from_proj({"proj":'geocent', "ellps":'WGS84', "datum":'WGS84'}, '+init=EPSG:4326')
>>> for pt in transproj.itransform([(-2704026.010, -4253051.810, 3895878.820)], radians=True): '{:.3f} {:.3f} {:.3f}'.format(*pt)
'-2.137 0.661 -20.531'
>>> transprojr = Transformer.from_proj('+init=EPSG:4326', {"proj":'geocent', "ellps":'WGS84', "datum":'WGS84'})
>>> for pt in transprojr.itransform([(-2.137, 0.661, -20.531)], radians=True): '{:.3f} {:.3f} {:.3f}'.format(*pt)
'-2704214.394 -4254414.478 3894270.731'
>>> transproj_eq = Transformer.from_proj('+init=EPSG:4326', '+proj=longlat +datum=WGS84 +no_defs +type=crs', skip_equivalent=True)
>>> for pt in transproj_eq.itransform([(-2.137, 0.661)]): '{:.3f} {:.3f}'.format(*pt)
'-2.137 0.661'
name

Name of the projection.

Type

str

to_wkt(version=<WktVersion.WKT2_2018: 'WKT2_2018'>, pretty=False)[source]

Convert the projection to a WKT string.

Version options:

  • WKT2_2015

  • WKT2_2015_SIMPLIFIED

  • WKT2_2018

  • WKT2_2018_SIMPLIFIED

  • WKT1_GDAL

  • WKT1_ESRI

Parameters

  • version (WktVersion) – The version of the WKT output. Default is WKT2_2018.

  • pretty (bool) – If True, it will set the output to be a multiline string. Defaults to False.

Returns

str

Return type

The WKT string.

transform(xx, yy, zz=None, tt=None, radians=False, errcheck=False, direction=<TransformDirection.FORWARD: 'FORWARD'>)[source]

Transform points between two coordinate systems.

Parameters

  • xx (scalar or array (numpy or python)) – Input x coordinate(s).

  • yy (scalar or array (numpy or python)) – Input y coordinate(s).

  • zz (scalar or array (numpy or python), optional) – Input z coordinate(s).

  • tt (scalar or array (numpy or python), optional) – Input time coordinate(s).

  • radians (boolean, optional) – If True, will expect input data to be in radians and will return radians if the projection is geographic. Default is False (degrees). Ignored for pipeline transformations.

  • errcheck (boolean, optional (default False)) – If True an exception is raised if the transformation is invalid. By default errcheck=False and an invalid transformation returns inf and no exception is raised.

  • direction (TransformDirection, optional) – The direction of the transform. Default is FORWARD.

Example:

>>> from pyproj import Transformer
>>> transformer = Transformer.from_crs("epsg:4326", "epsg:3857")
>>> x3, y3 = transformer.transform(33, 98)
>>> "%.3f  %.3f" % (x3, y3)
'10909310.098  3895303.963'
>>> pipeline_str = "+proj=pipeline +step +proj=longlat +ellps=WGS84 +step +proj=unitconvert +xy_in=rad +xy_out=deg"
>>> pipe_trans = Transformer.from_pipeline(pipeline_str)
>>> xt, yt = pipe_trans.transform(2.1, 0.001)
>>> "%.3f  %.3f" % (xt, yt)
'120.321  0.057'
>>> transproj = Transformer.from_proj({"proj":'geocent', "ellps":'WGS84', "datum":'WGS84'}, '+init=EPSG:4326')
>>> xpj, ypj, zpj = transproj.transform(-2704026.010, -4253051.810, 3895878.820, radians=True)
>>> "%.3f %.3f %.3f" % (xpj, ypj, zpj)
'-2.137 0.661 -20.531'
>>> transprojr = Transformer.from_proj('+init=EPSG:4326', {"proj":'geocent', "ellps":'WGS84', "datum":'WGS84'})
>>> xpjr, ypjr, zpjr = transprojr.transform(xpj, ypj, zpj, radians=True)
>>> "%.3f %.3f %.3f" % (xpjr, ypjr, zpjr)
'-2704026.010 -4253051.810 3895878.820'
>>> transformer = Transformer.from_proj("epsg:4326", 4326, skip_equivalent=True)
>>> xeq, yeq = transformer.transform(33, 98)
>>> "%.0f  %.0f" % (xeq, yeq)
'33  98'

pyproj.transform

pyproj.transformer.transform(p1, p2, x, y, z=None, tt=None, radians=False, errcheck=False, skip_equivalent=False, always_xy=False)[source]

x2, y2, z2 = transform(p1, p2, x1, y1, z1)

Transform points between two coordinate systems defined by the Proj instances p1 and p2.

The points x1,y1,z1 in the coordinate system defined by p1 are transformed to x2,y2,z2 in the coordinate system defined by p2.

z1 is optional, if it is not set it is assumed to be zero (and only x2 and y2 are returned). If the optional keyword ‘radians’ is True (default is False), then all input and output coordinates will be in radians instead of the default of degrees for geographic input/output projections. If the optional keyword ‘errcheck’ is set to True an exception is raised if the transformation is invalid. By default errcheck=False and inf is returned for an invalid transformation (and no exception is raised). If the optional kwarg skip_equivalent is true (default is False), it will skip the transformation operation if input and output projections are equivalent. If always_xy is toggled, the transform method will accept as input and return as output coordinates using the traditional GIS order, that is longitude, latitude for geographic CRS and easting, northing for most projected CRS.

In addition to converting between cartographic and geographic projection coordinates, this function can take care of datum shifts (which cannot be done using the __call__ method of the Proj instances). It also allows for one of the coordinate systems to be geographic (proj = ‘latlong’).

x,y and z can be numpy or regular python arrays, python lists/tuples or scalars. Arrays are fastest. For projections in geocentric coordinates, values of x and y are given in meters. z is always meters.

Example usage:

>>> from pyproj import Proj, transform
>>> # projection 1: UTM zone 15, grs80 ellipse, NAD83 datum
>>> # (defined by epsg code 26915)
>>> p1 = Proj(init='epsg:26915', preserve_units=False)
>>> # projection 2: UTM zone 15, clrk66 ellipse, NAD27 datum
>>> p2 = Proj(init='epsg:26715', preserve_units=False)
>>> # find x,y of Jefferson City, MO.
>>> x1, y1 = p1(-92.199881,38.56694)
>>> # transform this point to projection 2 coordinates.
>>> x2, y2 = transform(p1,p2,x1,y1)
>>> '%9.3f %11.3f' % (x1,y1)
'569704.566 4269024.671'
>>> '%9.3f %11.3f' % (x2,y2)
'569722.342 4268814.028'
>>> '%8.3f %5.3f' % p2(x2,y2,inverse=True)
' -92.200 38.567'
>>> # process 3 points at a time in a tuple
>>> lats = (38.83,39.32,38.75) # Columbia, KC and StL Missouri
>>> lons = (-92.22,-94.72,-90.37)
>>> x1, y1 = p1(lons,lats)
>>> x2, y2 = transform(p1,p2,x1,y1)
>>> xy = x1+y1
>>> '%9.3f %9.3f %9.3f %11.3f %11.3f %11.3f' % xy
'567703.344 351730.944 728553.093 4298200.739 4353698.725 4292319.005'
>>> xy = x2+y2
>>> '%9.3f %9.3f %9.3f %11.3f %11.3f %11.3f' % xy
'567721.149 351747.558 728569.133 4297989.112 4353489.645 4292106.305'
>>> lons, lats = p2(x2,y2,inverse=True)
>>> xy = lons+lats
>>> '%8.3f %8.3f %8.3f %5.3f %5.3f %5.3f' % xy
' -92.220  -94.720  -90.370 38.830 39.320 38.750'
>>> # test datum shifting, installation of extra datum grid files.
>>> p1 = Proj(proj='latlong',datum='WGS84')
>>> x1 = -111.5; y1 = 45.25919444444
>>> p2 = Proj(proj="utm",zone=10,datum='NAD27', preserve_units=False)
>>> x2, y2 = transform(p1, p2, x1, y1)
>>> "%s  %s" % (str(x2)[:9],str(y2)[:9])
'1402291.0  5076289.5'
>>> from pyproj import CRS
>>> c1 = CRS(proj='latlong',datum='WGS84')
>>> x1 = -111.5; y1 = 45.25919444444
>>> c2 = CRS(proj="utm",zone=10,datum='NAD27')
>>> x2, y2 = transform(c1, c2, x1, y1)
>>> "%s  %s" % (str(x2)[:9],str(y2)[:9])
'1402291.0  5076289.5'
>>> xeq, yeq = transform(4326, 4326, 30, 60, skip_equivalent=True)
>>> "%.0f %.0f" % (xeq, yeq)
'30 60'

pyproj.itransform

pyproj.transformer.itransform(p1, p2, points, switch=False, time_3rd=False, radians=False, errcheck=False, skip_equivalent=False, always_xy=False)[source]

points2 = itransform(p1, p2, points1) Iterator/generator version of the function pyproj.transform. Transform points between two coordinate systems defined by the Proj instances p1 and p2. This function can be used as an alternative to pyproj.transform when there is a need to transform a big number of coordinates lazily, for example when reading and processing from a file. Points1 is an iterable/generator of coordinates x1,y1(,z1) or lon1,lat1(,z1) in the coordinate system defined by p1. Points2 is an iterator that returns tuples of x2,y2(,z2) or lon2,lat2(,z2) coordinates in the coordinate system defined by p2. z are provided optionally.

Points1 can be:

  • a tuple/list of tuples/lists i.e. for 2d points: [(xi,yi),(xj,yj),….(xn,yn)]

  • a Nx3 or Nx2 2d numpy array where N is the point number

  • a generator of coordinates (xi,yi) for 2d points or (xi,yi,zi) for 3d

If optional keyword ‘switch’ is True (default is False) then x, y or lon,lat coordinates of points are switched to y, x or lat, lon. If the optional keyword ‘radians’ is True (default is False), then all input and output coordinates will be in radians instead of the default of degrees for geographic input/output projections. If the optional keyword ‘errcheck’ is set to True an exception is raised if the transformation is invalid. By default errcheck=False and inf is returned for an invalid transformation (and no exception is raised). If the optional kwarg skip_equivalent is true (default is False), it will skip the transformation operation if input and output projections are equivalent. If always_xy is toggled, the transform method will accept as input and return as output coordinates using the traditional GIS order, that is longitude, latitude for geographic CRS and easting, northing for most projected CRS.

Example usage:

>>> from pyproj import Proj, itransform
>>> # projection 1: WGS84
>>> # (defined by epsg code 4326)
>>> p1 = Proj(init='epsg:4326', preserve_units=False)
>>> # projection 2: GGRS87 / Greek Grid
>>> p2 = Proj(init='epsg:2100', preserve_units=False)
>>> # Three points with coordinates lon, lat in p1
>>> points = [(22.95, 40.63), (22.81, 40.53), (23.51, 40.86)]
>>> # transform this point to projection 2 coordinates.
>>> for pt in itransform(p1,p2,points): '%6.3f %7.3f' % pt
'411050.470 4497928.574'
'399060.236 4486978.710'
'458553.243 4523045.485'
>>> for pt in itransform(4326, 4326, [(30, 60)], skip_equivalent=True): '{:.0f} {:.0f}'.format(*pt)
'30 60'