r"""
Polyconic projection
====================

The polyconic projection, in Europe usually referred to as the American
polyconic projection, was introduced shortly before 1820 by the Swiss-American
cartographer Ferdinand Rodulph Hassler (1770-1843). As head of the Survey of
the Coast, he was looking for a projection that would give the least distortion
for mapping the coast of the United States. The projection acquired its name
from the construction of each parallel, which is achieved by projecting the
parallel onto the cone while it is rolled around the globe, along the central
meridian, tangent to that parallel. As a consequence, the projection involves
many cones rather than a single one used in regular conic projections.

The polyconic projection is neither equal-area, nor conformal. It is true to
scale without distortion along the central meridian. Each parallel is true to
scale as well, but the meridians are not as they get further away from the
central meridian. As a consequence, no parallel is standard because conformity
is lost with the lengthening of the meridians.

**poly**/\ [*lon0*/\ [*lat0*/]]\ *scale* or
**Poly**/\ [*lon0*/\ [*lat0*/]]\ *width*

- **poly** or **Poly**: Sets the projection type.
- *lon0*: Sets the central meridian [Optional].
- *lat0*: Sets the reference parallel [Optional]. When supplied, *lon0* must be
  supplied as well.
- *scale* or *width*: Sets the map size.
"""

# %%
import pygmt
from pygmt.params import Axis

fig = pygmt.Figure()
fig.coast(
    region=[-180, -20, 0, 90],
    projection="Poly/12c",
    frame=Axis(annot=True, tick=True, grid=True),
    land="seagreen",
    water="gray90",
)
fig.show()