add pypredict.groundtrack()

pypredict.py

@@ -1,9 +1,11 @@
 import subprocess
 import sys
+import time
+
 
 class missingSatellitePredictionError(Exception):
     def __init__(self):
-        self.description = "predict could not find aos, los of next pass"
+        self.description = "predict did not return data for the satellite"
         
     def __str__(self):
         return self.description
@@ -11,14 +13,32 @@ class missingSatellitePredictionError(Exception):
 def aoslos(satname):
     lines = subprocess.check_output(['predict','-p',satname]).split("\n")
     try:
-        aosTime=int(lines[0].split(" ")[0])
-        losTime=int(lines[-2].split(" ")[0])
+        aosTime=int(lines[0].split()[0])
+        losTime=int(lines[-2].split()[0])
         if losTime>aosTime:
             return (aosTime,losTime)
     except Exception:
         pass
     raise missingSatellitePredictionError()
 
+def groundtrack(satname, start=None, end=None):
+    if start is None:
+        start = int(time.time())
+    if end is None:
+        end = start+60*60*24
+    command = ['predict','-f',satname,str(start),str(end)+'m']
+    lines = subprocess.check_output(command).split("\n")
+    result = []
+    for line in lines:
+        try:
+            data = line.split()
+            if len(data)==12:  # expect 12 columns, pick out time, lat, lon
+                result.extend([int(data[j]) for j in [0,6,7] ])
+        except:
+            pass
+    if len(result)==0:
+        raise missingSatellitePredictionError()
+    return result