Steps blending v1 (#255)

This PR implements the STEPS blending approach in pysteps. 
It follows the original approaches by Bowler et al. (2006) and Seed et al. (2013).

Author: dnerini

.github/workflows/test_pysteps.yml

@@ -3,9 +3,13 @@ name: Test pysteps
 on:
   # Triggers the workflow on push or pull request events to the master branch
   push:
-    branches: [ master ]
+    branches:
+      - master
+      - pysteps-v2
   pull_request:
-    branches: [ master ]
+      branches:
+        - master
+        - pysteps-v2
 
 jobs:
   unit_tests:

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
 -   repo: https://github.com/psf/black
-    rev: 21.6b0
+    rev: 21.7b0
     hooks:
     - id: black
       language_version: python3

CONTRIBUTING.rst

@@ -231,7 +231,8 @@ Since PEP8 is a set of recommendations, these are the most important good coding
           </tr>
 
         </table>
-   (source: `Section 3.16.4, Google's python style guide <http://google.github.io/styleguide/pyguide.html>`__)
+
+(source: `Section 3.16.4, Google's python style guide <http://google.github.io/styleguide/pyguide.html>`__)
 
 - If you need to ignore part of the variables returned by a function,
   use "_" (single underscore) or __ (double underscore)::

ci/ci_test_env.yml

@@ -26,6 +26,7 @@ dependencies:
   - PyWavelets
   - pandas
   - scikit-image
+  - rasterio
   # Test dependencies
   - pytest
   - pytest-cov

doc/requirements.txt

@@ -1,8 +1,8 @@
-# Additional requeriments related to the documentation build only
+# Additional requirements related to the documentation build only
 sphinx
 sphinxcontrib.bibtex
 sphinx-book-theme
 sphinx_gallery
 scikit-image
 pandas
-
+git+https://github.com/pySTEPS/pysteps-nwp-importers.git@main#egg=pysteps_nwp_importers

doc/source/pysteps_reference/blending.rst

@@ -0,0 +1,12 @@
+================
+pysteps.blending
+================
+
+Implementation of blending methods for blending (ensemble) nowcasts with Numerical Weather Prediction (NWP) models.
+
+.. automodule:: pysteps.blending.interface
+.. automodule:: pysteps.blending.clim
+.. automodule:: pysteps.blending.linear_blending
+.. automodule:: pysteps.blending.skill_scores
+.. automodule:: pysteps.blending.steps
+.. automodule:: pysteps.blending.utils

doc/source/pysteps_reference/index.rst

@@ -14,6 +14,7 @@ available in pysteps.
     :caption: API Reference
 
     pysteps
+    blending
     cascade
     decorators
     extrapolation

doc/source/pysteps_reference/utils.rst

@@ -16,3 +16,4 @@ Implementation of miscellaneous utility functions.
 .. automodule:: pysteps.utils.spectral
 .. automodule:: pysteps.utils.tapering
 .. automodule:: pysteps.utils.transformation
+.. automodule:: pysteps.utils.reprojection

doc/source/references.bib

@@ -1,4 +1,14 @@
 
+@TECHREPORT{BPS2004,
+  AUTHOR = "N. E. Bowler and C. E. Pierce and A. W. Seed",
+  TITLE = "{STEPS}: A probabilistic precipitation forecasting scheme which merges an extrapolation nowcast with downscaled {NWP}",
+  INSTITUTION = "UK Met Office",
+  TYPE = "Forecasting Research Technical Report",
+  NUMBER = 433,
+  ADDRESS = "Wallingford, United Kingdom",
+  YEAR = 2004,
+}
+
 @ARTICLE{BPS2006,
   AUTHOR = "N. E. Bowler and C. E. Pierce and A. W. Seed",
   TITLE = "{STEPS}: A probabilistic precipitation forecasting scheme which merges an extrapolation nowcast with downscaled {NWP}",

doc/source/user_guide/install_pysteps.rst

@@ -36,7 +36,9 @@ Other optional dependencies include:
 * `pywavelets <https://pywavelets.readthedocs.io/en/latest/>`_
   (for intensity-scale verification)
 * `pandas <https://pandas.pydata.org/>`_ and
-  `scikit-image <https://scikit-image.org/>`_ (for the DATing and LINDA nowcast methods)
+  `scikit-image <https://scikit-image.org/>`_ (for advanced feature detection methods)
+* `rasterio <https://rasterio.readthedocs.io/en/latest/>`_ (for the reprojection module)
+
 
 **Important**: If you only want to use pysteps, you can continue reading below.
 But, if you want to contribute to pysteps or edit the package, you need to install