Mrms bounding box (#222)

* Fix bounding box coordinates

* Add missing metadata

pysteps/io/importers.py

@@ -393,24 +393,27 @@ def import_mrms_grib(filename, extent=None, window_size=4, **kwargs):
     pr = pyproj.Proj(proj_params)
     proj_def = " ".join([f"+{key}={value} " for key, value in proj_params.items()])
 
+    xsize = grib_msg["iDirectionIncrementInDegrees"] * window_size[0]
+    ysize = grib_msg["jDirectionIncrementInDegrees"] * window_size[1]
+
     x1, y1 = pr(ul_lon, lr_lat)
     x2, y2 = pr(lr_lon, ul_lat)
 
     metadata = dict(
         institution="NOAA National Severe Storms Laboratory",
-        xpixelsize=grib_msg["iDirectionIncrementInDegrees"] * window_size[0],
-        ypixelsize=grib_msg["jDirectionIncrementInDegrees"] * window_size[1],
+        xpixelsize=xsize,
+        ypixelsize=ysize,
         unit="mm/h",
         accutime=2.0,
         transform=None,
         zerovalue=0,
         projection=proj_def.strip(),
         yorigin="upper",
         threshold=_get_threshold_value(precip),
-        x1=x1,
-        x2=x2,
-        y1=y1,
-        y2=y2,
+        x1=x1 - xsize / 2,
+        x2=x2 + xsize / 2,
+        y1=y1 - ysize / 2,
+        y2=y2 + ysize / 2,
         cartesian_unit="degrees",
     )
 

pysteps/tests/test_io_mrms_grib.py

@@ -2,6 +2,7 @@
 
 import os
 
+import numpy as np
 import pytest
 import xarray as xr
 from numpy.testing import assert_array_almost_equal
@@ -53,6 +54,11 @@ def test_io_import_mrms_grib():
             assert metadata[key] == expected_array_metadata[key]
 
 
+    x = np.arange(metadata["x1"], metadata["x2"], metadata["xpixelsize"])
+    y = np.arange(metadata["y1"], metadata["y2"], metadata["ypixelsize"])
+    assert y.size == precip_full.shape[0]
+    assert x.size == precip_full.shape[1]
+
     # The full latitude range is (20.005, 54.995)
     # The full longitude range is (230.005, 299.995)