Extract class time step selection

mikeio/_time.py

@@ -0,0 +1,69 @@
+from __future__ import annotations
+from datetime import datetime
+from dataclasses import dataclass
+from typing import List, Iterable, Optional
+
+import pandas as pd
+
+
+@dataclass
+class DateTimeSelector:
+    """Helper class for selecting time steps from a pandas DatetimeIndex"""
+
+    index: pd.DatetimeIndex
+
+    def isel(
+        self,
+        x: Optional[
+            int | Iterable[int] | str | datetime | pd.DatetimeIndex | slice
+        ] = None,
+    ) -> List[int]:
+        """Select time steps from a pandas DatetimeIndex
+
+        Parameters
+        ----------
+        x : int, Iterable[int], str, datetime, pd.DatetimeIndex, slice
+            Time steps to select, negative indices are supported
+
+        Returns
+        -------
+        List[int]
+            List of indices in the range (0, len(index)
+        Examples
+        --------
+        >>> idx = pd.date_range("2000-01-01", periods=4, freq="D")
+        >>> dts = DateTimeSelector(idx)
+        >>> dts.isel(None)
+        [0, 1, 2, 3]
+        >>> dts.isel(0)
+        [0]
+        >>> dts.isel(-1)
+        [3]
+        """
+
+        indices = list(range(len(self.index)))
+
+        if x is None:
+            return indices
+
+        if isinstance(x, int):
+            return [indices[x]]
+
+        if isinstance(x, (datetime, str)):
+            loc = self.index.get_loc(x)
+            if isinstance(loc, int):
+                return [loc]
+            elif isinstance(loc, slice):
+                return list(range(loc.start, loc.stop))
+
+        if isinstance(x, slice):
+            if isinstance(x.start, int) or isinstance(x.stop, int):
+                return indices[x]
+            else:
+                s = self.index.slice_indexer(x.start, x.stop)
+                return list(range(s.start, s.stop))
+
+        if isinstance(x, Iterable):
+            return [self.isel(t)[0] for t in x]
+
+        return indices

mikeio/dataset/_data_utils.py

@@ -1,11 +1,12 @@
 from __future__ import annotations
 import re
-from datetime import datetime
-from typing import Iterable, Sequence, Sized, Tuple
+from typing import Iterable, Sequence, Sized, Tuple, Union, List
 
 import numpy as np
 import pandas as pd
 
+from .._time import DateTimeSelector
+
 
 def _to_safe_name(name: str) -> str:
     tmp = re.sub("[^0-9a-zA-Z]", "_", name)
@@ -18,45 +19,19 @@ def _n_selected_timesteps(x: Sized, k: slice | Sized) -> int:
     return len(k)
 
 
-def _get_time_idx_list(time: pd.DatetimeIndex, steps):
+def _get_time_idx_list(time: pd.DatetimeIndex, steps) -> Union [List[int], slice]:
     """Find list of idx in DatetimeIndex"""
 
-    if isinstance(steps, str):
-        parts = steps.split(",")
-        if len(parts) == 1:
-            parts.append(parts[0])  # end=start
-
-        if parts[0] == "":
-            steps = slice(parts[1])  # stop only
-        elif parts[1] == "":
-            steps = slice(parts[0], None)  # start only
-        else:
-            steps = slice(parts[0], parts[1])
+    # indexing with a slice needs to be handled differently, since slicing returns a view
 
-    if isinstance(steps, (list, tuple)) and isinstance(
-        steps[0], (str, datetime, np.datetime64, pd.Timestamp)
-    ):
-        steps = pd.DatetimeIndex(steps)
-    if isinstance(steps, pd.DatetimeIndex):
-        return time.get_indexer(steps)
-    if isinstance(steps, (str, datetime, np.datetime64, pd.Timestamp)):
-        steps = slice(steps, steps)
     if isinstance(steps, slice):
-        try:
-            s = time.slice_indexer(
-                steps.start,
-                steps.stop,
-            )
-            steps = list(range(s.start, s.stop))
-        except TypeError:
-            pass  # TODO this seems fishy!
-            # steps = list(range(*steps.indices(len(time))))
-    elif isinstance(steps, int):
-        steps = [steps]
-    # TODO what is the return type of this function
-    return steps
+        if isinstance(steps.start, int) and isinstance(steps.stop, int):
+            return steps
 
+    dts = DateTimeSelector(time)
+    return dts.isel(steps)
 
+# TODO this only used by DataArray, so consider to move it there
 class DataUtilsMixin:
     """DataArray Utils"""
 
@@ -107,7 +82,7 @@ def _set_by_boolean_mask(data: np.ndarray, mask: np.ndarray, value) -> None:
     def _parse_time(time) -> pd.DatetimeIndex:
         """Allow anything that we can create a DatetimeIndex from"""
         if time is None:
-            time = [pd.Timestamp(2018, 1, 1)]
+            time = [pd.Timestamp(2018, 1, 1)] # TODO is this the correct epoch?
         if isinstance(time, str) or (not isinstance(time, Iterable)):
             time = [time]
 

mikeio/dfs/_dfs.py

@@ -2,7 +2,7 @@
 import warnings
 from abc import abstractmethod
 from datetime import datetime
-from typing import Iterable, List, Optional, Tuple, Sequence
+from typing import List, Optional, Tuple, Sequence
 import numpy as np
 import pandas as pd
 from tqdm import tqdm, trange
@@ -23,6 +23,7 @@
 from ..eum import EUMType, EUMUnit, ItemInfo, ItemInfoList, TimeStepUnit
 from ..exceptions import DataDimensionMismatch, ItemsError
 from ..spatial import GeometryUndefined
+from .._time import DateTimeSelector
 
 
 def _read_item_time_step(
@@ -77,10 +78,10 @@ def _valid_item_numbers(
     n_items_file = len(dfsItemInfo) - start_idx
     if items is None:
         return list(range(n_items_file))
-    
+
     # Handling scalar and sequences is a bit tricky
-    
-    item_numbers : List[int] = []
+
+    item_numbers: List[int] = []
 
     # check if items is a scalar (int or str)
     if isinstance(items, (int, str)):
@@ -89,13 +90,13 @@ def _valid_item_numbers(
                 dfsItemInfo=dfsItemInfo, search=items, start_idx=start_idx
             )
         elif isinstance(items, str):
-            item_number  = _item_numbers_by_name(dfsItemInfo, [items], ignore_first)[0]
+            item_number = _item_numbers_by_name(dfsItemInfo, [items], ignore_first)[0]
             return [item_number]
         elif isinstance(items, int):
             if (items < 0) or (items >= n_items_file):
                 raise ItemsError(n_items_file)
             return [items]
-    
+
     assert isinstance(items, Sequence)
     for item in items:
         if isinstance(item, str):
@@ -116,78 +117,48 @@ def _valid_item_numbers(
 
 def _valid_timesteps(dfsFileInfo: DfsFileInfo, time_steps) -> Tuple[bool, List[int]]:
 
+    time_axis = dfsFileInfo.TimeAxis
+
     single_time_selected = False
-    if isinstance(time_steps, int) and np.isscalar(time_steps):
+    if isinstance(time_steps, (int, datetime)):
         single_time_selected = True
 
-    n_steps_file = dfsFileInfo.TimeAxis.NumberOfTimeSteps
-    if time_steps is None:
-        return single_time_selected, list(range(n_steps_file))
+    nt = time_axis.NumberOfTimeSteps
 
-    if isinstance(time_steps, int):
-        time_steps = [time_steps]
+    if time_axis.TimeAxisType != TimeAxisType.CalendarEquidistant:
+        # TODO is this the proper epoch, should this magic number be somewhere else?
+        start_time_file = datetime(1970, 1, 1)
+    else:
+        start_time_file = time_axis.StartDateTime
 
-    if isinstance(time_steps, str):
-        parts = time_steps.split(",")
-        if len(parts) == 1:
-            parts.append(parts[0])  # end=start
-
-        if parts[0] == "":
-            time_steps = slice(parts[1])  # stop only
-        elif parts[1] == "":
-            time_steps = slice(parts[0], None)  # start only
-        else:
-            time_steps = slice(parts[0], parts[1])
+    if time_axis.TimeAxisType in (
+        TimeAxisType.CalendarEquidistant,
+        TimeAxisType.TimeEquidistant,
+    ):
+        time_step_file = time_axis.TimeStep
+        freq = pd.Timedelta(seconds=time_step_file)
+        time = pd.date_range(start_time_file, periods=nt, freq=freq)
+    elif time_axis.TimeAxisType == TimeAxisType.CalendarNonEquidistant:
+        idx = list(range(nt))
 
-    if isinstance(time_steps, (slice, pd.Timestamp, datetime, pd.DatetimeIndex)):
-        if dfsFileInfo.TimeAxis.TimeAxisType != TimeAxisType.CalendarEquidistant:
-            # TODO: handle non-equidistant calendar
-            raise ValueError(
-                "Only equidistant calendar files are supported for this type of time_step argument"
-            )
+        if isinstance(time_steps, int):
+            return True, [idx[time_steps]]
+        return single_time_selected, idx
 
-        start_time_file = dfsFileInfo.TimeAxis.StartDateTime
-        time_step_file = dfsFileInfo.TimeAxis.TimeStep
-        freq = pd.Timedelta(seconds=time_step_file)
-        time = pd.date_range(start_time_file, periods=n_steps_file, freq=freq)
+    dts = DateTimeSelector(time)
 
-    if isinstance(time_steps, slice):
-        if isinstance(time_steps.start, int) or isinstance(time_steps.stop, int):
-            time_steps = list(range(*time_steps.indices(n_steps_file)))
-        else:
-            s = time.slice_indexer(time_steps.start, time_steps.stop)
-            time_steps = list(range(s.start, s.stop))
-    elif isinstance(time_steps, Sequence) and isinstance(time_steps[0], int):
-        time_steps = np.array(time_steps)
-        time_steps[time_steps < 0] = n_steps_file + time_steps[time_steps < 0]
-        time_steps = list(time_steps)
-
-        if max(time_steps) > (n_steps_file - 1):
-            raise IndexError(f"Timestep cannot be larger than {n_steps_file}")
-        if min(time_steps) < 0:
-            raise IndexError(f"Timestep cannot be less than {-n_steps_file}")
-    elif isinstance(time_steps, Iterable):
-        steps = []
-        for t in time_steps:
-            _, step = _valid_timesteps(dfsFileInfo, t)
-            steps.append(step[0])
-        single_time_selected = len(steps) == 1
-        time_steps = steps
-
-    elif isinstance(time_steps, (pd.Timestamp, datetime)):
-        s = time.slice_indexer(time_steps, time_steps)
-        time_steps = list(range(s.start, s.stop))
-    #elif isinstance(time_steps, pd.DatetimeIndex):
-    #    time_steps = list(time.get_indexer(time_steps))
+    idx = dts.isel(time_steps)
 
-    else:
-        raise TypeError(f"Indexing is not possible with {type(time_steps)}")
-    if len(time_steps) == 1:
-        single_time_selected = True
-    return single_time_selected, time_steps
+    if isinstance(time_steps, str):
+        if len(idx) == 1:
+            single_time_selected = True
+
+    return single_time_selected, idx
 
 
-def _item_numbers_by_name(dfsItemInfo, item_names: List[str], ignore_first: bool=False) -> List[int]:
+def _item_numbers_by_name(
+    dfsItemInfo, item_names: List[str], ignore_first: bool = False
+) -> List[int]:
     """Utility function to find item numbers
 
     Parameters
@@ -243,7 +214,9 @@ def _get_item_info(
         item_numbers = list(range(len(dfsItemInfo) - first_idx))
 
     item_numbers = [i + first_idx for i in item_numbers]
-    items = [ItemInfo.from_mikecore_dynamic_item_info(dfsItemInfo[i]) for i in item_numbers]
+    items = [
+        ItemInfo.from_mikecore_dynamic_item_info(dfsItemInfo[i]) for i in item_numbers
+    ]
     return ItemInfoList(items)
 
 
@@ -387,7 +360,9 @@ def _read_header(self):
         }:
             self._start_time = dfs.FileInfo.TimeAxis.StartDateTime
         else:  # relative time axis
-            self._start_time = datetime(1970, 1, 1)
+            self._start_time = datetime(
+                1970, 1, 1
+            )  # TODO is this the proper epoch, should this magic number be somewhere else?
         if hasattr(dfs.FileInfo.TimeAxis, "TimeStep"):
             self._timestep_in_seconds = (
                 dfs.FileInfo.TimeAxis.TimeStep
@@ -502,7 +477,9 @@ def append(self, data: Dataset) -> None:
                     darray = d.reshape(d.size, 1)[:, 0]
 
                 if self._ndim == 3:
-                    raise NotImplementedError("Append is not yet available for 3D files")
+                    raise NotImplementedError(
+                        "Append is not yet available for 3D files"
+                    )
 
                 if self._is_equidistant:
                     self._dfs.WriteItemTimeStepNext(0, darray.astype(np.float32))
@@ -717,7 +694,9 @@ def time(self) -> pd.DatetimeIndex:
         # this will fail if the TimeAxisType is not calendar and equidistant, but that is ok
         if not self._is_equidistant:
             raise NotImplementedError("Not implemented for non-equidistant files")
-        return pd.date_range(start=self.start_time, periods=self.n_timesteps, freq=f"{self.timestep}S")
+        return pd.date_range(
+            start=self.start_time, periods=self.n_timesteps, freq=f"{self.timestep}S"
+        )
 
     @property
     def projection_string(self):

tests/test_consistency.py

@@ -422,12 +422,13 @@ def test_read_dfs_time_slice_str():
         assert dsr.shape == dsgetitem.shape
 
 
-def test_read_dfs_time_selection_str_comma():
+def test_read_dfs_time_selection_str_slice():
 
     extensions = ["dfs0", "dfs2", "dfs1", "dfs0"]
     for ext in extensions:
         filename = f"tests/testdata/consistency/oresundHD.{ext}"
-        time = "2018-03-08,2018-03-10"
+
+        time = slice("2018-03-08","2018-03-10")
         ds = mikeio.read(filename=filename)
         dssel = ds.sel(time=time)
         assert dssel.n_timesteps == 3

tests/test_dataarray.py

@@ -1311,7 +1311,7 @@ def test_time_selection():
 
     assert das_t.shape == (24,)
 
-    with pytest.raises(IndexError):
+    with pytest.raises(KeyError):
         # not in time
         ds.sel(time="1997-09-15 00:00")
 

tests/test_dfsu_layered.py

@@ -297,7 +297,7 @@ def test_read_column_interp_time_and_select_time():
     salinity_st = da.sel(time="1997-09-15 23:00")  # single time-step
     assert salinity_st.n_timesteps == 1
 
-    with pytest.raises(IndexError):
+    with pytest.raises(KeyError):
         # not in time
         da.sel(time="1997-09-15 00:00")