add wraparound capability to drawmeridians.

Author: Jeff Whitaker

Changelog

@@ -1,6 +1,11 @@
 since version 1.0.2
            * fix typo in setup.py (replace "!= ['sdist','clean']" with
              "not in ['sdist','clean']").
+           * make sure drawmeridians can handle wrap-around (so that
+             if projection is defined in -180 to 0 and user asks for
+             meridians from 180 to 360 to be drawn, it should work).
+             Only affects projections 'mill','gall','merc' and 'cyl'.
+
 version 1.0.2 (git tag v1.0.2)
            * update include geos from 3.2.0 to 3.3.1 so it compiles with gcc
              4.6.

lib/mpl_toolkits/basemap/__init__.py

@@ -2132,6 +2132,21 @@ def drawmeridians(self,meridians,color='k',linewidth=1., zorder=None,\
         associated with each meridian. Deleting an item from the
         dictionary removes the correpsonding meridian from the plot.
         """
+        # for cylindrical projections, try to handle wraparound (i.e. if
+        # projection is defined in -180 to 0 and user asks for meridians from
+        # 180 to 360 to be drawn, it should work)
+        if self.projection in _cylproj:
+            def addlon(meridians,madd):
+                minside = (madd >= self.llcrnrlon and madd <= self.urcrnrlon)
+                if minside and madd not in meridians: meridians.append(madd)
+                return meridians 
+            merids = list(meridians)
+            meridians = []
+            for m in merids:
+                meridians = addlon(meridians,m)
+                meridians = addlon(meridians,m+360)
+                meridians = addlon(meridians,m-360)
+            meridians.sort()
         # if celestial=True, don't use "E" and "W" labels.
         if labelstyle is None and self.celestial:
             labelstyle="+/-"