Add_time_utils

Author: ANDREWNGT

kessler/cdm.py

@@ -14,7 +14,7 @@
 import datetime
 import copy
 import pandas as pd
-
+from . import time_utils
 from . import util
 
 
@@ -191,11 +191,18 @@ def __eq__(self, other):
         if isinstance(other, ConjunctionDataMessage):
             return hash(self) == hash(other)
         return False
+    
+    
 
     def set_header(self, key, value):
         if key in self._keys_header:
             if key in self._keys_with_dates:
                 # We have a field with a date string as the value. Check if the string is in the format needed by the CCSDS 508.0-B-1 standard
+                timeFormat = time_utils.getCcsdsTimeFormat(value)
+                idx = timeFormat.find('DDD')
+                if idx!=-1:
+                    [DateNum, DateVec] = time_utils.DOY2Date(value[idx:idx+3], value[0:4])
+                    value = str(DateVec[0]) +'-' + str(DateVec[1]) + '-' + str(DateVec[2]) + 'T' + value[idx+4:-1] #figure this out!!!
                 try:
                     _ = datetime.datetime.strptime(value, '%Y-%m-%dT%H:%M:%S.%f')
                 except Exception as e:

kessler/time_utils.py

@@ -0,0 +1,83 @@
+import datetime
+def getCcsdsTimeFormat(timeString):
+
+    '''
+    Adapted by Andrew Ng, 18/3/2022.
+    Original MATLAB source code found at: https://github.com/nasa/CARA_Analysis_Tools/blob/master/two-dimension_Pc/Main/TransformationCode/TimeTransformations/getCcsdsTimeFormat.m
+    The CCSDS time format is required to be of the general form
+
+    yyyy-[mm-dd|ddd]THH:MM:SS[.F*][Z]
+    (1) The date and time fields are separated by a "T".
+    (2) The date field has a four digit year followed by either a two digit 
+        month and two digit day, or a three digit day-of-year.  
+    (3) The year, month, day, and day-of-year fields are separated by a dash.
+    (4) The hours, minutes and seconds fields are each two digits separated 
+        by colons.
+    (5) The fraction of seconds is optional and can have any number of
+        digits.
+    (6) If a fraction of seconds is provided, it is separated from the two
+        digit seconds by a period.
+    (7) The time string can end with an optional "Z" time zone indicator
+    '''
+    timeFormat = []
+    numT = timeString.count('T')
+    if numT == -1:
+        # Case when this is 'T' does not exist in timeString
+        print(f"*** Error -- Invalid CCSDS time string: {timeString}")
+        print(f"    No 'T' separator found between date and time portions of the string\n")
+        return
+    elif numT > 1:
+        print(f"*** Error -- Invalid CCSDS time string: {timeString} \n")
+        print(f"    More than one 'T' separator found between date and time portions of the string\n")
+        return
+    idxT = timeString.find('T')
+    if idxT ==10:
+        timeFormat = "yyyy-mm-ddTHH:MM:SS"
+    elif idxT ==8:
+        timeFormat = "yyyy-DDDTHH:MM:SS"
+    else: 
+        print(f"*** Error -- Invalid CCSDS time string: {timeString} \n", timeString)
+        print(f"    Date format not one of yyyy-mm-dd or yyyy-DDD\n")
+        return
+    # % Check if 'Z' time zone indicator appended to the string
+    if timeString[-1]=='Z':
+        zOpt = True
+    else:
+        zOpt = False
+    # % Find location of the fraction of seconds decimal separator
+    numDecimal = timeString.count('.')
+    if numDecimal > 1:
+        print(f"*** Error -- Invalid CCSDS time string: {timeString} \n")
+        print(f"    More than one fraction of seconds decimal separator ('.') found.\n")
+        timeFormat = []
+        return
+    idxDecimal = timeString.find('.')
+    nfrac = 0
+    if numDecimal != 0:
+        if zOpt:
+            nfrac = len(timeString) - 1 - idxDecimal -1
+        else: 
+            nfrac = len(timeString) - 1 - idxDecimal
+    if nfrac > 0:
+        fracStr = '.' + ('F'*nfrac)
+    else:
+        fracStr = ""
+    if zOpt:
+        fracStr = fracStr+'Z'
+    timeFormat = timeFormat+fracStr
+    return timeFormat
+
+def DOY2Date(DOY, YEAR):
+    '''
+    Written by Andrew Ng, 18/03/2022, 
+    Based on source code @ https://github.com/nasa/CARA_Analysis_Tools/blob/master/two-dimension_Pc/Main/TransformationCode/TimeTransformations/DOY2Date.m
+    Use the datetime python package. 
+    DOY2DATE  - Converts Day of Year (DOY) to date number and full 
+            calendar date. 
+
+    '''
+    # Calculate datetime format
+    DateNum = datetime.datetime(int(YEAR), 1, 1) + datetime.timedelta(int(DOY) - 1)
+    # Split datetime object into a date list
+    DateVec = [DateNum.year, DateNum.month, DateNum.day, DateNum.hour, DateNum.minute]
+    return DateNum, DateVec