Merge pull request #3 from ANDREWNGT/Add_time_utils

Add time utils

Author: Sceki

kessler/cdm.py

@@ -14,7 +14,6 @@
 import datetime
 import copy
 import pandas as pd
-
 from . import util
 
 
@@ -191,11 +190,15 @@ 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
+                time_format = util.get_ccsds_time_format(value)
+                idx = time_format.find('DDD')
+                if idx!=-1:
+                    value = util.doy_2_date(value, value[idx:idx+3], value[0:4], idx)
                 try:
                     _ = datetime.datetime.strptime(value, '%Y-%m-%dT%H:%M:%S.%f')
                 except Exception as e:

kessler/util.py

@@ -349,3 +349,93 @@ def progress_bar_end(message=None):
     print()
     if message is not None:
         print(message)
+
+def get_ccsds_time_format(time_string):
+    '''
+    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
+    get_ccsds_time_format  -  process and outputs the format of the time string extracted from the CDM. 
+    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
+
+    Args:
+        - time_string(``str``): Original time string stored in CDM.
+    Returns: 
+        - time_format(``str``): Outputs the format of the time string. It must be of the form yyyy-[mm-dd|ddd]THH:MM:SS[.F*][Z], otherwise it is invalid and a RuntimeError is raised.
+
+    '''
+    time_format = []
+    numT = time_string.count('T')
+    if numT == -1:
+        # Case when this is 'T' does not exist in time_string
+        raise RuntimeError(f"*** Error -- Invalid CCSDS time string: {time_string}\nNo 'T' separator found between date and time portions of the string")
+    elif numT > 1:
+        raise RuntimeError(f"*** Error -- Invalid CCSDS time string: {time_string} \nMore than one 'T' separator found between date and time portions of the string")
+    idx_T = time_string.find('T')
+    if idx_T ==10:
+        time_format = "yyyy-mm-ddTHH:MM:SS"
+    elif idx_T ==8:
+        time_format = "yyyy-DDDTHH:MM:SS"
+    else: 
+        raise RuntimeError(f"*** Error -- Invalid CCSDS time string: {time_string} \nDate format not one of yyyy-mm-dd or yyyy-DDD.\n")
+    # % Check if 'Z' time zone indicator appended to the string
+    if time_string[-1]=='Z':
+        z_opt = True
+    else:
+        z_opt = False
+    # % Find location of the fraction of seconds decimal separator
+    num_decimal = time_string.count('.')
+    if num_decimal > 1:
+        #time_format = []
+        raise RuntimeError(f"*** Error -- Invalid CCSDS time string: {time_string}\nMore than one fraction of seconds decimal separator ('.') found.\n")
+    idx_decimal = time_string.find('.')
+    nfrac = 0
+    if num_decimal != 0:
+        if z_opt:
+            nfrac = len(time_string) - 1 - idx_decimal -1
+        else: 
+            nfrac = len(time_string) - 1 - idx_decimal
+    if nfrac > 0:
+        frac_str = '.' + ('F'*nfrac)
+    else:
+        frac_str = ""
+    if z_opt:
+        frac_str = frac_str+'Z'
+    time_format = time_format + frac_str
+    return time_format
+
+def doy_2_date(value, doy, year, idx):
+    '''
+    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. 
+    doy_2_date  - Converts Day of Year (DOY) date format to date format.
+    
+    Args:
+        - value(``str``): Original date time string with day of year format "YYYY-DDDTHH:MM:SS.ff"
+        - doy  (``str``): The day of year in the DOY format. 
+        - year (``str``): The year.
+        - idx  (``int``): Index of the start of the original "value" string at which characters 'DDD' are found. 
+    Returns: 
+        -value (``str``): Transformed date in traditional date format. i.e.: "YYYY-mm-ddTHH:MM:SS.ff"
+
+    '''
+    # Calculate datetime format
+    date_num = datetime.datetime(int(year), 1, 1) + datetime.timedelta(int(doy) - 1)
+
+    # Split datetime object into a date list
+    date_vec = [date_num.year, date_num.month, date_num.day, date_num.hour, date_num.minute]
+    # Extract final date string. Use zfill() to pad year, month and day fields with zeroes if not filling up sufficient spaces. 
+    value = str(date_vec[0]).zfill(4) +'-' + str(date_vec[1]).zfill(2) + '-' + str(date_vec[2]).zfill(2) + 'T' + value[idx+4:-1] 
+    return value

tests/test_util.py

@@ -111,3 +111,47 @@ def test_from_cartesian_to_rtn_2(self):
         state_rtn, _ = kessler.util.from_cartesian_to_rtn(state_xyz)
         self.assertAlmostEqual(np.linalg.norm(state_xyz[0]), np.linalg.norm(state_rtn[0]), places=1)
         self.assertAlmostEqual(np.linalg.norm(state_xyz[1]), np.linalg.norm(state_rtn[1]), places=1)
+
+    def test_get_ccsds_time_format(self):
+        # This test is written by Andrew Ng, 19/03/22. It makes use of example CDMs provided by the NASA CARA
+        # analysis repo at https://github.com/nasa/CARA_Analysis_Tools/tree/master/two-dimension_Pc/UnitTest/InputFiles.
+        test_case1 = "2000-01-01T00:00:00.000" #From AlfanoTestCase11.cdm
+        test_case2 = "2018-229T13:56:33.000" # From DensityDecorrelationTestCaseCDM.txt
+        test_case1_correct = "yyyy-mm-ddTHH:MM:SS.FFF"
+        test_case2_correct = "yyyy-DDDTHH:MM:SS.FFF"
+
+        self.assertEqual(kessler.util.get_ccsds_time_format(test_case1), test_case1_correct)
+        self.assertEqual(kessler.util.get_ccsds_time_format(test_case2), test_case2_correct) 
+
+    def test_doy_2_date(self):
+        # This test is written by Andrew Ng, 19/03/22. It makes use of example CDMs provided by the NASA CARA
+        # analysis repo at https://github.com/nasa/CARA_Analysis_Tools/tree/master/two-dimension_Pc/UnitTest/InputFiles.
+        example1 = "2010-202T12:25:19.000" # From SingleCovTestCase1-4.cdm
+        example2 = "2018-229T13:56:33.000" # From DensityDecorrelationTestCaseCDM.txt
+        example3 = "2010-365T00:00:00.000" # Check that works at the final day of a non leap year
+        example4 = "2010-001T00:00:00.000" # Check that works at the first day of a year
+        example5 = "2012-366T00:00:00.000" # Check that works at the final day of a leap year
+        
+        doy_1 = example1[5:5+3] 
+        year_1= example1[0:4]
+        doy_2 = example2[5:5+3]
+        year_2= example2[0:4]
+        doy_3 = example3[5:5+3] 
+        year_3= example3[0:4]
+        doy_4 = example4[5:5+3]
+        year_4= example4[0:4]
+        doy_5 = example5[5:5+3] 
+        year_5= example5[0:4]
+
+        test_case1_correct = "2010-07-21T12:25:19.00"
+        test_case2_correct = "2018-08-17T13:56:33.00"
+        test_case3_correct = "2010-12-31T00:00:00.00"
+        test_case4_correct = "2010-01-01T00:00:00.00"
+        test_case5_correct = "2012-12-31T00:00:00.00"
+        
+        self.assertEqual(kessler.util.doy_2_date(example1, doy_1, year_1, 5), test_case1_correct)
+        self.assertEqual(kessler.util.doy_2_date(example2, doy_2, year_2, 5), test_case2_correct) 
+        self.assertEqual(kessler.util.doy_2_date(example3, doy_3, year_3, 5), test_case3_correct)
+        self.assertEqual(kessler.util.doy_2_date(example4, doy_4, year_4, 5), test_case4_correct) 
+        self.assertEqual(kessler.util.doy_2_date(example5, doy_5, year_5, 5), test_case5_correct) 
+