def itransform(p1, p2, points, radians=False, switch=False):
"""
points2 = transform(p1, p2, points1, radians=False)
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 optional keyword 'radians' is True (default is False) and p1
is defined in geographic coordinate (pj.is_latlong() is True),
x1,y1 is interpreted as radians instead of the default degrees.
Similarly, if p2 is defined in geographic coordinates and
radians=True, x2, y2 are returned in radians instead of degrees.
if p1.is_latlong() and p2.is_latlong() both are False, the
radians keyword has no effect.
Example usage:
>>> # projection 1: WGS84
>>> # (defined by epsg code 4326)
>>> p1 = Proj(init='epsg:4326')
>>> # projection 2: GGRS87 / Greek Grid
>>> p2 = Proj(init='epsg:2100')
>>> # 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'
"""
if not isinstance(p1, Proj):
raise TypeError("p1 must be a Proj class")
if not isinstance(p2, Proj):
raise TypeError("p2 must be a Proj class")
it = iter(points) # point iterator
# get first point to check stride
try:
fst_pt = next(it)
except StopIteration:
raise ValueError("iterable must contain at least one point")
stride = len(fst_pt)
if stride not in (2, 3):
raise ValueError("points can contain up to 3 coordinates")
# create a coordinate sequence generator etc. x1,y1,z1,x2,y2,z2,....
# chain so the generator returns the first point that was already acquired
coord_gen = chain(fst_pt,
(coords[c] for coords in it for c in range(stride)))
while True:
# create a temporary buffer storage for the next 64 points (64*stride*8 bytes)
buff = array('d', islice(coord_gen, 0, 64 * stride))
if len(buff) == 0:
break
_proj._transform_sequence(p1, p2, stride, buff, radians, switch)
for pt in zip(*([iter(buff)] * stride)):
yield pt
def itransform(p1, p2, points, radians=False, switch=False):
"""
points2 = transform(p1, p2, points1, radians=False)
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 optional keyword 'radians' is True (default is False) and p1
is defined in geographic coordinate (pj.is_latlong() is True),
x1,y1 is interpreted as radians instead of the default degrees.
Similarly, if p2 is defined in geographic coordinates and
radians=True, x2, y2 are returned in radians instead of degrees.
if p1.is_latlong() and p2.is_latlong() both are False, the
radians keyword has no effect.
Example usage:
>>> # projection 1: WGS84
>>> # (defined by epsg code 4326)
>>> p1 = Proj(init='epsg:4326')
>>> # projection 2: GGRS87 / Greek Grid
>>> p2 = Proj(init='epsg:2100')
>>> # 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'
"""
if not isinstance(p1, Proj):
raise TypeError("p1 must be a Proj class")
if not isinstance(p2, Proj):
raise TypeError("p2 must be a Proj class")
it = iter(points) # point iterator
# get first point to check stride
try:
fst_pt = next(it)
except StopIteration:
raise ValueError("iterable must contain at least one point")
stride = len(fst_pt)
if stride not in (2,3):
raise ValueError("points can contain up to 3 coordinates")
# create a coordinate sequence generator etc. x1,y1,z1,x2,y2,z2,....
# chain so the generator returns the first point that was already acquired
coord_gen = chain(fst_pt, (coords[c] for coords in it for c in range(stride)))
while True:
# create a temporary buffer storage for the next 64 points (64*stride*8 bytes)
buff = array('d', islice(coord_gen, 0, 64*stride))
if len(buff) == 0:
break;
_proj._transform_sequence(p1, p2, stride, buff, radians, switch)
for pt in zip(*([iter(buff)]*stride)):
yield pt