Fix flipped coastlines in pseudocylindrical projections

Solves GitHub issue #463.

The bug appears in the `pyproj` transition from version 1.9.6 to
2.0.0, which corresponds when `pyproj` migrated from PROJ 4.x to
PROJ 6.0.

Author: molinav

CHANGELOG.md

@@ -19,6 +19,8 @@ https://semver.org/spec/v2.0.0.html
   ETOPO, Shaded Relief) to be shown behind the map background when the
   map boundary is not initialised manually (solves issue [#577], thanks
   to @YilongWang).
+- Fix flipped coastlines with pseudocylindrical projections when `lon_0`
+  is greater than 0 deg (solves issue [#463], thanks to @YilongWang).
 
 ## [1.3.8] - 2023-08-18
 
@@ -1070,6 +1072,8 @@ https://github.com/matplotlib/basemap/issues/488
 https://github.com/matplotlib/basemap/issues/487
 [#476]:
 https://github.com/matplotlib/basemap/pull/476
+[#463]:
+https://github.com/matplotlib/basemap/issues/463
 [#461]:
 https://github.com/matplotlib/basemap/issues/461
 [#456]:

packages/basemap/src/mpl_toolkits/basemap/__init__.py

@@ -4181,8 +4181,8 @@ def warpimage(self,image="bluemarble",scale=None,**kwargs):
                     lonsr,latsr = self(x,y,inverse=True)
                     mask = ma.zeros((ny,nx,4),np.int8)
                     lon_0 = self.projparams['lon_0']
-                    lonright = lon_0+180.
-                    lonleft = lon_0-180.
+                    lonright = lon_0 + 180. - 1E-10
+                    lonleft = lon_0 - 180. + 1E-10
                     x1 = np.array(ny*[0.5*(self.xmax + self.xmin)],np.float64)
                     y1 = np.linspace(self.ymin, self.ymax, ny)
                     lons1, lats1 = self(x1,y1,inverse=True)

packages/basemap/src/mpl_toolkits/basemap/proj.py

@@ -195,8 +195,8 @@ def __init__(self,projparams,llcrnrlon,llcrnrlat,
                     raise ValueError(_lower_left_out_of_bounds)
         elif self.projection in _pseudocyl:
             self._proj4 = pyproj.Proj(projparams)
-            xtmp,urcrnry = self(projparams['lon_0'],90.)
-            urcrnrx,xtmp = self(projparams['lon_0']+180.,0)
+            xtmp, urcrnry = self(projparams['lon_0'], 90.)
+            urcrnrx, xtmp = self(projparams['lon_0'] + 180. - 1E-10, 0)
             llcrnrx = -urcrnrx
             llcrnry = -urcrnry
             if self.ellipsoid and self.projection in ['kav7','eck4','mbtfpq']:
@@ -236,8 +236,8 @@ def __init__(self,projparams,llcrnrlon,llcrnrlat,
                     if urcrnrx > 1.e20 or urcrnry > 1.e20:
                         raise ValueError(_upper_right_out_of_bounds)
             elif self.projection in _pseudocyl:
-                xtmp,urcrnry = self(projparams['lon_0'],90.)
-                urcrnrx,xtmp = self(projparams['lon_0']+180.,0)
+                xtmp, urcrnry = self(projparams['lon_0'], 90.)
+                urcrnrx, xtmp = self(projparams['lon_0'] + 180. - 1E-10, 0)
         else:
             urcrnrx = urcrnrlon
             urcrnry = urcrnrlat