timeseries frequency not longer required

core.py

@@ -19,12 +19,13 @@ class FlagParams:
     ASSIGN = "assign"
 
 
-def _inferFrequency(data):
-    return pd.tseries.frequencies.to_offset(pd.infer_freq(data.index))
-
-
-def _periodToTicks(period, freq):
-    return int(ceil(pd.to_timedelta(period)/pd.to_timedelta(freq)))
+def flagPeriod(flagger: BaseFlagger, flags: pd.Series, freq: str) -> pd.Series:
+    out = flags.copy()
+    for start in flags.index[flagger.isFlagged(flags)]:
+        stop = start + pd.to_timedelta(freq)
+        out.loc[start:stop] = flagger.setFlag(flags.loc[start:stop],
+                                              *np.atleast_1d(flags.loc[start]))
+    return out
 
 
 def flagNext(flagger: BaseFlagger, flags: pd.Series, n: int) -> pd.Series:
@@ -41,23 +42,18 @@ def runner(meta, flagger, data, flags=None, nodata=np.nan):
     if flags is None:
         flags = pd.DataFrame(index=data.index)
 
-    # NOTE:
-    # We need an index frequency in order to calculate ticks
-    # from given periods further down the road. Maybe this
-    # restriction should only be enforced when we really
-    # need a time series...
-    data.index.freq = _inferFrequency(data)
-    if not data.index.freq:
-        raise TypeError("cannot infer time frequency from dataset")
-
     # the required meta data columns
     fields = [Fields.VARNAME, Fields.STARTDATE, Fields.ENDDATE, Fields.ASSIGN]
 
+    # NOTE:
     # get to know every variable from meta
+    # should go into a separate function
     for idx, configrow in meta.iterrows():
         varname, _, _, assign = configrow[fields]
-        if varname not in flags and (varname in data or varname not in data and assign is True):
-            col_flags = flagger.initFlags(pd.DataFrame(index=data.index, columns=[varname]))
+        if varname not in flags and \
+           (varname in data or varname not in data and assign is True):
+            col_flags = flagger.initFlags(pd.DataFrame(index=data.index,
+                                                       columns=[varname]))
             flags = col_flags if flags.empty else flags.join(col_flags)
 
     # NOTE:
@@ -102,8 +98,9 @@ def runner(meta, flagger, data, flags=None, nodata=np.nan):
             # duration given in 'flag_period'
             flag_period = flag_params.pop(Params.FLAGPERIOD, None)
             if flag_period:
-                flag_params[Params.FLAGVALUES] = _periodToTicks(
-                    flag_period, data.index.freq)
+                fchunk[varname] = flagPeriod(flagger,
+                                             fchunk[varname],
+                                             data.index.freq)
 
             # flag a certain amount of values after condition is met,
             # number given in 'flag_values'

test/test_core.py

@@ -5,7 +5,7 @@ import pytest
 import numpy as np
 import pandas as pd
 
-from core import runner, flagNext, prepareMeta
+from core import runner, flagNext, flagPeriod, prepareMeta
 from config import Fields
 from flagger import SimpleFlagger, DmpFlagger, PositionalFlagger
 from test.common import initData
@@ -131,6 +131,29 @@ def test_flagNext(flagger):
     assert (result_idx == expected_idx).all()
 
 
+@pytest.mark.parametrize("flagger", TESTFLAGGERS)
+def test_flagPeriod(flagger):
+    """
+    Test if the flagNext functionality works as expected
+    """
+    data = initData().iloc[:, 1]
+    flags = flagger.initFlags(data)
+
+    idx = [0, 1, 2]
+    flags.iloc[idx] = flagger.setFlag(flags.iloc[idx])
+
+    tdelta = pd.to_timedelta("4h")
+    flags = flagPeriod(flagger, flags.copy(), tdelta)
+    expected_dates = set(flags[flagger.isFlagged(flags)].index)
+
+    dates = set()
+    for start in flags.index[idx]:
+        stop = start + tdelta
+        dates = dates | set(flags[start:stop].index)
+
+    assert expected_dates == dates
+
+
 if __name__ == "__main__":
 
     # NOTE: PositionalFlagger is currently broken, going to fix it when needed
@@ -139,6 +162,7 @@ if __name__ == "__main__":
     # for flagger in [DmpFlagger()]:
         test_temporalPartitioning(flagger)
         test_flagNext(flagger)
+        test_flagPeriod(flagger)
         test_missingConfig(flagger)
         test_missingVariable(flagger)
         test_assignVariable(flagger)