Merge pull request #775 from xylar/fix-decimal-time

Allow decimal time steps in `isomip_plus`

compass/ocean/tests/isomip_plus/forward.py

@@ -1,13 +1,13 @@
 import os
 import shutil
-import time
 
 import numpy as np
 import xarray
 
 from compass.model import run_model
 from compass.ocean.tests.isomip_plus.evap import update_evaporation_flux
 from compass.ocean.tests.isomip_plus.viz.plot import MoviePlotter
+from compass.ocean.time import get_time_interval_string
 from compass.step import Step
 
 
@@ -148,11 +148,8 @@ def run(self):
         dt_per_km = config.getfloat('isomip_plus', 'dt_per_km')
         dt_btr_per_km = config.getfloat('isomip_plus', 'dt_btr_per_km')
 
-        # https://stackoverflow.com/a/1384565/7728169
-        # Note: this will drop any fractional seconds, which is usually okay
-        dt = time.strftime('%H:%M:%S', time.gmtime(dt_per_km * resolution))
-        btr_dt = time.strftime(
-            '%H:%M:%S', time.gmtime(dt_btr_per_km * resolution))
+        dt = get_time_interval_string(seconds=dt_per_km * resolution)
+        btr_dt = get_time_interval_string(seconds=dt_btr_per_km * resolution)
 
         options = dict(config_dt=f"'{dt}'",
                        config_btr_dt=f"'{btr_dt}'")

compass/ocean/tests/isomip_plus/ssh_adjustment.py

@@ -1,6 +1,5 @@
-import time
-
 from compass.ocean.iceshelf import adjust_ssh
+from compass.ocean.time import get_time_interval_string
 from compass.step import Step
 
 
@@ -86,14 +85,11 @@ def run(self):
         dt_per_km = config.getfloat('isomip_plus', 'dt_per_km')
         dt_btr_per_km = config.getfloat('isomip_plus', 'dt_btr_per_km')
 
-        # https://stackoverflow.com/a/1384565/7728169
-        # Note: this will drop any fractional seconds, which is usually okay
-        dt = time.strftime('%H:%M:%S', time.gmtime(dt_per_km * resolution))
-        btr_dt = time.strftime(
-            '%H:%M:%S', time.gmtime(dt_btr_per_km * resolution))
+        dt = get_time_interval_string(seconds=dt_per_km * resolution)
+        btr_dt = get_time_interval_string(seconds=dt_btr_per_km * resolution)
 
-        options = dict(config_dt="'{}'".format(dt),
-                       config_btr_dt="'{}'".format(btr_dt))
+        options = dict(config_dt=f"'{dt}'",
+                       config_btr_dt=f"'{btr_dt}'")
         self.update_namelist_at_runtime(options)
 
         iteration_count = config.getint('ssh_adjustment', 'iterations')

compass/ocean/time.py

@@ -0,0 +1,38 @@
+import time
+
+import numpy as np
+
+
+def get_time_interval_string(days=None, seconds=None):
+    """
+    Convert a time interval in days and/or seconds to a string for use in a
+    model config option.  If both are provided, they will be added
+
+    Parameters
+    ----------
+    days : float, optional
+        A time interval in days
+
+    seconds : float, optional
+        A time interval in seconds
+
+    Returns
+    -------
+    time_str : str
+        The time as a string in the format "DDDD_HH:MM:SS.SS"
+
+    """
+    sec_per_day = 86400
+    total = 0.
+    if seconds is not None:
+        total += seconds
+    if days is not None:
+        total += sec_per_day * days
+
+    day_part = int(total / sec_per_day)
+    sec_part = total - day_part * sec_per_day
+    sec_decimal = sec_part - np.floor(sec_part)
+    # https://stackoverflow.com/a/1384565/7728169
+    seconds_str = time.strftime('%H:%M:%S', time.gmtime(sec_part))
+    time_str = f'{day_part:04d}_{seconds_str}.{int(sec_decimal * 1e3):03d}'
+    return time_str