missing_value = 'N/A' led to fail (#84)

* missing_value = 'N/A' led to fail

* added test to make sure reading in var with ASCII missing val will work

* fix for mac

Lib/avariable.py

@@ -136,8 +136,11 @@ def __init__ (self, parent=None, variableNode=None):
         self._grid_ = None      # Variable grid, if any
         if not hasattr(self,'missing_value'):
             self.missing_value = None
-        elif numpy.isnan(self.missing_value):
-          self.missing_value = None
+        else:
+            if isinstance(self.missing_value,basestring):
+                self.missing_value = None
+            elif numpy.isnan(self.missing_value):
+              self.missing_value = None
 
         # Reminder: children to define self.shape and set self.id
 
@@ -418,7 +421,16 @@ def getMissing(self, asarray=0):
         if asarray==0 and isinstance(mv, numpy.ndarray):
             mv = mv[0]
         if type(mv) is types.StringType and self.dtype.char not in ['?','c','O','S']:
-            mv = float(mv)
+            try:
+                mv = float(mv)
+            except:
+                if hasattr(self,'_FillValue'):
+                    try:
+                        mv = float(self._FillValue)
+                    except:
+                        mv = None
+                else:
+                    mv = None
         return mv
 
     def _setmissing(self, name, value):

Test/test_missing_ascii.py

@@ -0,0 +1,50 @@
+import basetest
+import subprocess
+import cdms2
+import os
+
+class TestMissingASCII(basetest.CDMSBaseTest):
+    def testMissingASCII(self):
+        nc_dump = """
+        netcdf tmp_test {
+        dimensions:
+            axis_0 = 2 ;
+            axis_1 = 2 ;
+        variables:
+            double axis_0(axis_0) ;
+            double axis_1(axis_1) ;
+            double var(axis_0, axis_1) ;
+                var:missing_value = "N/A" ;
+
+        // global attributes:
+                :Conventions = "CF-1.0" ;
+        data:
+
+         axis_0 = 0, 1 ;
+
+         axis_1 = 0, 1 ;
+
+         var =
+          1, 1,
+          1, 1 ;
+        }
+        """
+
+        f=open("tmp_test.asc","w")
+        f.write(nc_dump)
+        f.close()
+
+        subprocess.call("ncgen -b tmp_test.asc".split())
+
+        f=cdms2.open("tmp_test.nc")
+        v=f("var")
+        f.close()
+
+        self.assertEqual(v.missing_value,1.e20)
+
+        os.remove("tmp_test.asc")
+        os.remove("tmp_test.nc")
+
+
+if __name__ == "__main__":
+    basetest.run()