make scolor available regardless, only try to plot unknowns if there are some

email_stats.py

@@ -50,14 +50,15 @@ plt.minorticks_on()
 plt.title(args.title)
 a = mailbox.mbox(args.mbox)
 
+scolor = cubehelix.cmap(startHue=240, endHue=-300,
+                        minSat=1, maxSat=2.5,
+                        minLight=.3, maxLight=.8,
+                        gamma=.9)
+
 pldata = {}
 if args.sendercolors:
     slist = args.sendercolors.split(',')
     nsend = len(slist)
-    scolor = cubehelix.cmap(startHue=240, endHue=-300,
-                            minSat=1, maxSat=2.5,
-                            minLight=.3, maxLight=.8,
-                            gamma=.9)
     for item in slist:
         pldata[item] = []
 pldata['unknown'] = []
@@ -93,13 +94,14 @@ if args.sendercolors:
                       label=plid[1],
                       xdate=True)
 
-plt.plot_date(np.array(pldata['unknown'])[:,0],
-              np.array(pldata['unknown'])[:,1],
-              color=scolor((plid[0] + 1 ) / (nsend + 1)),
-              marker='.',
-              #tz=z.tzname(),
-              label='unknown',
-              xdate=True)
+if len(pldata['unknown']) > 0:
+    plt.plot_date(np.array(pldata['unknown'])[:,0],
+                  np.array(pldata['unknown'])[:,1],
+                  color=scolor(1),
+                  marker='.',
+                  #tz=z.tzname(),
+                  label='unknown',
+                  xdate=True)
 
 if args.sendercolors:
     plt.legend(loc='upper left', ncol=nsend + 1)