Shapely supports map projections and other arbitrary transformations of geometric objects.

Shapely支持地图投影和其他对几何对象的变换操作。

• shapely.ops.transform(func, geom)

Applies func to all coordinates of geom and returns a new geometry of the same type from the transformed coordinates.

将func应用于geom的所有坐标，并根据转换后的坐标返回一个相同类型的新几何对象。

func maps x, y, and optionally z to output xp, yp, zp. The input parameters may be iterable types like lists or arrays or single values. The output shall be of the same type: scalars in, scalars out; lists in, lists out.

func将x, y,和可选的z映射到输出xp, yp, zp。输入参数可以是可迭代的类型，如列表或数组或单个值。输出应是相同的类型：标量输入，标量输出；列表输入，列表输出。

transform tries to determine which kind of function was passed in by calling func first with n iterables of coordinates, where n is the dimensionality of the input geometry. If func raises a TypeError when called with iterables as arguments, then it will instead call func on each individual coordinate in the geometry.

transform试图通过首先调用func的n个坐标迭代变量来确定传递的是哪种函数，其中n是输入几何对象的维度。如果func在以迭代变量作为参数调用时引发了TypeError，那么它将在几何对象中的每个坐标上调用func。

New in version 1.2.18.

For example, here is an identity function applicable to both types of input (scalar or array).

例如，这里有一个适用于两种输入类型（标量或数组）的函数。

def id_func(x, y, z=None):
    return tuple(filter(None, [x, y, z]))

g2 = transform(id_func, g1)

If using pyproj>=2.1.0, the preferred method to project geometries is:

如果使用pyproj>=2.1.0，投影几何图形的首选方法是：

import pyproj

from shapely import Point
from shapely.ops import transform

wgs84_pt = Point(-72.2495, 43.886)

wgs84 = pyproj.CRS('EPSG:4326')
utm = pyproj.CRS('EPSG:32618')

project = pyproj.Transformer.from_crs(wgs84, utm, always_xy=True).transform
utm_point = transform(project, wgs84_pt)

It is important to note that in the example above, the always_xy kwarg is required as Shapely only supports coordinates in X,Y order, and in PROJ 6 the WGS84 CRS uses the EPSG-defined Lat/Lon coordinate order instead of the expected Lon/Lat.

需要注意的是，在上面的例子中，需要always_xy参数，因为Shapely只支持X、Y顺序的坐标，而在PROJ6中，WGS84 CRS使用EPSG定义的Lat/Lon坐标顺序，而不是预期的Lon/Lat。

If using pyproj < 2.1, then the canonical example is:

如果使用 pyproj < 2.1，那么典型的例子是：

from functools import partial
import pyproj

from shapely.ops import transform

wgs84 = pyproj.Proj(init='epsg:4326')
utm = pyproj.Proj(init='epsg:32618')

project = partial(
    pyproj.transform,
    wgs84,
    utm)

utm_point = transform(project, wgs84_pt)

Lambda expressions such as the one in

Lambda表达式

g2 = transform(lambda x, y, z=None: (x+1.0, y+1.0), g1)

also satisfy the requirements for func.

也满足func的要求。

标签 Python-GIS, Shapely