Teach gpsprof to handle the case where altitudes aren't available.

1 files changed, 9 insertions, 4 deletions

diff --git a/gpsprof b/gpsprof
index 7e5d70bf..705decab 100755
--- a/gpsprof
+++ b/gpsprof
@@ -68,14 +68,17 @@ class spaceplot:
             for i in range(len(recentered)):
                 (lat, lon) = recentered[i][:2]
                 (raw1, raw2, alt) = self.fixes[i]
-                if alt > -999 :
+                if alt > gps.ALTITUDE_NOT_VALID:
 			alt_sum += alt
 			alt_num += 1
 		if lon > lon_max :
 			lon_max = lon
                 self.fp.write("%f	%f	%f	%f	%f\n" % (lat, lon, raw1, raw2, alt))
             self.fp.flush()
-	    alt_avg = alt_sum / alt_num
+            if alt_num == 0:
+                alt_avg = gps.ALTITUDE_NOT_VALID
+            else:
+                alt_avg = alt_sum / alt_num
             if centroid[0] < 0:
                 latstring = "%fS" % -centroid[0]
             elif centroid[0] == 0:
@@ -97,7 +100,8 @@ class spaceplot:
             fmt += 'set style line 3 pt 2 # Looks good on X11\n'
             fmt += 'set xlabel "Meters east from %s"\n' % lonstring
             fmt += 'set ylabel "Meters north from %s"\n' % latstring
-            fmt += 'set y2label "Meters Altitude from %f"\n' % alt_avg
+            if alt_avg != gps.ALTITUDE_NOT_VALID:
+                fmt += 'set y2label "Meters Altitude from %f"\n' % alt_avg
             fmt += 'set border 15\n'
             fmt += 'set ytics nomirror\n'
             fmt += 'set y2tics\n'
@@ -111,7 +115,8 @@ class spaceplot:
             fmt += "set arrow from 0,-chlen to 0,chlen nohead\n"
             fmt += 'plot cx(t, cep),cy(t, cep) title "CEP (50%%) = %f meters",  ' % (cep_meters)
             fmt += ' "%s" using 1:2 with points ls 3 title "%d GPS fixes" , ' % (file, len(self.fixes))
-            fmt += '"%s" using ( %f ):($5 > -999 ? $5 - %f : 1/0) axes x1y2 with points ls 2 title " %d Altitude fixes, Average = %f" \n' % ( file, lon_max + 1, alt_avg, alt_num, alt_avg)
+            if alt_avg != gps.ALTITUDE_NOT_VALID:
+                fmt += '"%s" using ( %f ):($5 > %d ? $5 - %f : 1/0) axes x1y2 with points ls 2 title " %d Altitude fixes, Average = %f" \n' % ( file, lon_max + 1, gps.ALTITUDE_NOT_VALID, alt_avg, alt_num, alt_avg)
             return fmt
 
 class uninstrumented: