Fix gis module (#213)

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### Pull Request Checklist:
- [ ] This PR addresses an already opened issue (for bug fixes /
features)
  - This PR fixes #xyz
- [X] (If applicable) Documentation has been added / updated (for bug
fixes / features).
- [X] (If applicable) Tests have been added.
- [ ] CHANGELOG.rst has been updated (with summary of main changes).
- [ ] Link to issue (:issue:`number`) and pull request (:pull:`number`)
has been added.

### What kind of change does this PR introduce?
GIS module's tests were failing because the Planetary Computer's doesn't
allow anonymous access to their blob storage anymore. However, they
provide with their python API a way to sign (SAS token) the blobs
allowing us to fetch the required files again.

### Does this PR introduce a breaking change?
No

### Other information:

docs/notebooks/gis.ipynb

@@ -849,6 +849,13 @@
     ")"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We can also extract the surface properties for the same `gpd.GeoDataFrame` : "
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 10,
@@ -972,6 +979,13 @@
     "xhgis.surface_properties(gdf)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Again, for convenience, we can output the results in `xarray.Dataset` format : "
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 11,

docs/notebooks/hydrological_modelling.ipynb

@@ -31,6 +31,8 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "import planetary_computer\n",
+    "\n",
     "import xhydro as xh\n",
     "import xhydro.modelling as xhm\n",
     "\n",
@@ -52,7 +54,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "id": "3",
    "metadata": {
     "editable": true,
@@ -166,7 +168,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 9,
    "id": "7",
    "metadata": {},
    "outputs": [],
@@ -179,6 +181,7 @@
     "# Acquire the Copernicus DEM for the area covered by the watershed\n",
     "catalog = pystac_client.Client.open(\n",
     "    \"https://planetarycomputer.microsoft.com/api/stac/v1\",\n",
+    "    modifier=planetary_computer.sign_inplace,\n",
     ")\n",
     "search = catalog.search(\n",
     "    collections=[\"cop-dem-glo-90\"],\n",

src/xhydro/gis.py

@@ -15,6 +15,7 @@
 import matplotlib.pyplot as plt
 import numpy as np
 import pandas as pd
+import planetary_computer
 import pystac_client
 import rasterio
 import rasterio.features
@@ -270,11 +271,9 @@ def _recursive_upstream_lookup(
 
 
 def _flatten(x, dim="time"):
-    # FIXME: assert statements should only be found in test code
-    assert isinstance(x, xr.DataArray)  # noqa: S101
-    if len(x[dim].values) > len(set(x[dim].values)):
-        x = x.groupby(dim).map(stackstac.mosaic)
-
+    if isinstance(x, xr.DataArray):
+        if len(x[dim].values) > len(set(x[dim].values)):
+            x = x.groupby(dim).map(stackstac.mosaic)
     return x
 
 
@@ -324,6 +323,7 @@ def surface_properties(
 
     catalog = pystac_client.Client.open(
         "https://planetarycomputer.microsoft.com/api/stac/v1",
+        modifier=planetary_computer.sign_inplace,
     )
 
     search = catalog.search(
@@ -489,6 +489,7 @@ def land_use_classification(
     """
     catalog = pystac_client.Client.open(
         "https://planetarycomputer.microsoft.com/api/stac/v1",
+        modifier=planetary_computer.sign_inplace,
     )
     collection = catalog.get_collection(collection)
     ia = ItemAssetsExtension.ext(collection)
@@ -552,6 +553,7 @@ def land_use_plot(
     """
     catalog = pystac_client.Client.open(
         "https://planetarycomputer.microsoft.com/api/stac/v1",
+        modifier=planetary_computer.sign_inplace,
     )
 
     collection = catalog.get_collection(collection)