Transforming Shapely Polygon and MultiPolygon objects

While shapely doesn't natively understand coordinate systems, shapely.ops.transform() can do that along with pyproj. If pyproj.Proj can understand your both of your coordinate systems, then it can be made into a function that shapely can transform with.

From the shapely docs:

pyproj >= 2.1.0

import pyproj

from shapely.geometry 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)

pyproj < 2.1

from functools import partial
import pyproj
from shapely.ops import transform

project = partial(
    pyproj.transform,
    pyproj.Proj(init='epsg:4326'), # source coordinate system
    pyproj.Proj(init='epsg:26913')) # destination coordinate system

g2 = transform(project, g1)  # apply projection

While not a Shapely solution, using GeoPandas allows for relatively straightforward projection. For example, if we want to convert a shapefile to ESPG 4326:

import geopandas as gpd

HabModelEnviro = gpd.GeoDataFrame.from_file('data/HabModelEnviro.shp').replace({-999: None})

HabModelEnviroWGS84 = HabModelEnviro.to_crs({'proj':'longlat', 'ellps':'WGS84', 'datum':'WGS84'})

If you're using pyproj2, it's much easier to use a Transformer. Here's an example:

import pyproj
from shapely.ops import transform

project = pyproj.Transformer.from_proj(
    pyproj.Proj(init='epsg:4326'), # source coordinate system
    pyproj.Proj(init='epsg:26913')) # destination coordinate system

# g1 is a shapley Polygon

g2 = transform(project.transform, g1)  # apply projection

This is also much faster, becase pyproj does not need to recreate the projection for every point.