Add create_test_plot script; can check if GCPy is installed properly

gcpy/examples/plotting/create_test_plot.py
- Script to create a dummy plot that renders to the screen.
  Useful for checking if "import gcpy" works properly.

gcpy/examples/plotting/__init__.py
- Added create_test_plot.py

CHANGELOG.md
- Updated accordingly

Signed-off-by: Bob Yantosca <[email protected]>

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to GCPy will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased] - TBD
+### Added
+- Example script `create_test_plot.py`, which can be used to check that GCPy has been installed properly
+
+
 ## [1.4.1] - 2023-12-08
 ### Fixed
 - Now use the proper default value for the `--weightsdir` argument to `gcpy/file_regrid.py`

gcpy/examples/plotting/__init__.py

@@ -1,5 +1,6 @@
 """
 GCPy import script
 """
+from .create_test_plot import *
 from .plot_single_panel import *
 from .plot_comparisons import *

gcpy/examples/plotting/create_test_plot.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+"""
+Creates a dummy xarray DataArray object for testing the single_panel
+plotting routine.  This script can be a useful check to see whether the
+GCPy mamba/conda environment has been successfully installed.
+"""
+
+import numpy as np
+import xarray as xr
+import matplotlib.pyplot as plt
+import gcpy
+
+
+def main():
+    """
+    Main program: Creates a dummy plot
+    """
+
+    # Get X and Y coordinate arrays
+    n_lat = 181
+    n_lon = 361
+    lat_vals = np.linspace(-90, 90, n_lat)
+    lon_vals = np.linspace(-180, 180, n_lon)
+
+    # Create a dummy numpy array for plotting
+    # Populate it with the distance from the center of the plot
+    data = np.zeros([n_lat, n_lon])
+    for lat in range(n_lat):
+        for lon in range(n_lon):
+            data[lat, lon] = np.sqrt(lon_vals[lon]**2 + lat_vals[lat]**2)
+
+    # Create a Dataarray from the numpy array
+    darr = xr.DataArray(
+        data=data,
+        dims=["lat", "lon"],
+        coords=dict(
+            lat=("lat", lat_vals),
+            lon=("lon", lon_vals),
+        ),
+    )
+
+    # Create a plot
+    gcpy.plot.single_panel(
+        darr,
+        plot_type="single_level",
+        title="Test plot to check GCPy import",
+        extent=[-180, 180, -90, 90],
+        comap=plt.get_cmap("RdBu_r")
+    )
+    plt.show()
+
+
+if __name__ == '__main__':
+    main()