geoschem · yantosca · Sep 5, 2025
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -12,7 +12,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Added `gcpy_environment_py314.ym1` to specify the GCPy environment packages with Python 3.14 
 - Added GitHub action `build-gcpy-environment-py314.yml` to test building the GCPy environment with Python 3.14
 - Added call to drop GC-Classic variables when regridding a GC-Classic restart file to cubed-sphere 
-
+- Added `examples/grids/display_gcclassic_grid_info.py`  to display info about a GEOS-Chem Classic horizontal grid
+
 ### Changed
 - Modified criteria for terminating read of log files in `benchmark_scrape_gcclassic_timers.py` to avoid being spoofed by  output that is attached by Intel VTune
 - Moved `gprofng_text_to_data_units` to function `text_to_data_units` in `gcpy/plot/core.py` so that it can be used by `gprofng_functions` and `vtune_plot_hotspots`

diff --git a/gcpy/examples/__init__.py b/gcpy/examples/__init__.py
@@ -5,6 +5,7 @@
 #from .bpch_to_nc import *
 from .diagnostics import *
 from .dry_run import *
+from .grids import *
 from .plotting import *
 from .timeseries import *
 from .working_with_files import *

diff --git a/gcpy/examples/grids/display_gcclassic_grid_info.py b/gcpy/examples/grids/display_gcclassic_grid_info.py
@@ -0,0 +1,156 @@
+#!/usr/bin/env python3
+"""
+Prints information about a GEOS-Chem Classic horizontal grid
+"""
+from gcpy.grid import make_grid_LL
+
+
+def print_vals(values):
+    """
+    Prints a list of numbers 8 columns wide with 5 decimal places.
+
+    Args
+    values : list-like : Values to be displayed
+    """
+    cols = 8
+    for i in range(0, len(values), cols):
+        line = "".join(f"{x:11.5f}" for x in values[i:i+cols])
+        print(line)
+
+
+def create_grid_and_print_info(grid_params):
+    """
+    Creates a grid object and prints its metadata.
+
+    Args
+    grid_params : tuple : Resolution, lon range, lat range
+    """
+
+    # Arguments
+    res = grid_params[0]
+    lon_range = grid_params[1]
+    lat_range = grid_params[2]
+
+    # Create a grid object
+    out_extent = [lon_range[0], lon_range[1], lat_range[0], lat_range[1]]
+    grid = make_grid_LL(res, out_extent=out_extent)
+
+    # Print metadata
+    print("resolution")
+    print(res)
+    print("longitude centers")
+    print_vals(grid["lon"])
+    print("latitude centers")
+    print_vals(grid["lat"])
+    print("longitude edges")
+    print_vals(grid["lon_b"])
+    print("latitude edges")
+    print_vals(grid["lat_b"])
+
+
+def get_grid_parameters(selection):
+    """
+    Returns metadata about a given grid
+
+    Args
+    selection   : int   : Number of the selected grid
+
+    Returns
+    grid_params : tuple : Resolution, lon range, lat range
+
+    """
+    #    Resolution       # Lon range            # Lat range
+    grids = [
+        ("4.0x5.0",       [-180.0,    180.0   ], [-90.0,  90.0 ]),  # 4.0   x 5.0     global
+        ("2.0x2.5",       [-180.0,    180.0   ], [-90.0,  90.0 ]),  # 2.0   x 2.5     global
+        ("0.5x0.625",     [-180.0,    180.0   ], [-90.0,  90.0 ]),  # 0.5   x 0.625   global
+        ("0.5x0.625",     [  60.0,    150.0   ], [-11.0,  55.0 ]),  # 0.5   x 0.625   AS
+        ("0.5x0.625",     [ -30.0,     50.0   ], [ 30.0,  70.0 ]),  # 0.5   x 0.625   EU
+        ("0.5x0.625",     [-140.0,    -40.0   ], [ 10.0,  70.0 ]),  # 0.5   x 0.625   NA
+        ("0.25x0.3125",   [-180.0,    180.0   ], [-90.0,  90.0 ]),  # 0.25  x 0.3125  global
+        ("0.25x0.3125",   [ -20.0,     52.8125], [-37.0,  40.0 ]),  # 0.25  x 0.3125  AF
+        ("0.25x0.3125",   [  70.0,    140.0   ], [ 32.75, 61.25]),  # 0.25  x 0.3125  AS
+        ("0.25x0.3125",   [ -15.0,     40.0   ], [ 15.0,  55.0 ]),  # 0.25  x 0.3125  EU
+        ("0.25x0.3125",   [ -20.0,     70.0   ], [ 12.0,  44.0 ]),  # 0.25  x 0.3125  ME
+        ("0.25x0.3125",   [-130.0,    -60.0   ], [  9.75, 60.0 ]),  # 0.25  x 0.3125  NA
+        ("0.25x0.3125",   [ 110.0,    180.0   ], [-50.0,   5.0 ]),  # 0.25  x 0.3125  OC
+        ("0.25x0.3125",   [ -87.8125, -31.25  ], [-59.0,  16.0 ]),  # 0.25  x 0.3125  SA
+        ("0.25x0.3125",   [  20.0,    180.0   ], [ 41.0,  83.0 ]),  # 0.25  x 0.3125  RU
+        ("0.125x0.15625", [-180.0,    180.0   ], [-90.0,  90.0 ]),  # 0.125 x 0.15625 global
+        ("0.125x0.15625", [ -20.0,     52.8125], [-59.0,  16.0 ]),  # 0.125 x 0.15625 AF
+        ("0.125x0.15625", [  70.0,    140.0   ], [ 15.0,  55.0 ]),  # 0.125 x 0.15625 AS
+        ("0.125x0.15625", [ -15.0,     40.0   ], [ 32.75, 61.25]),  # 0.125 x 0.15625 EU
+        ("0.125x0.15625", [-130.0,    -60.0   ], [  9.75, 60.0 ]),  # 0.125 x 0.15625 NA
+        ("0.125x0.15625", [ -87.8125, -31.25  ], [-59.0,  16.0 ]),  # 0.125 x 0.15625 SA
+    ]
+
+    return grids[selection]
+
+
+def display_menu():
+    """
+    Displays a menu of grids to choose from.
+
+    Returns
+    selection : int : Number of the grid selected by the user
+    """
+    msg = """\
+Please select a GEOS-Chem Classic horizontal grid:
+
+1.  4.0\u00B0   x 5.0\u00B0     global
+
+2.  2.0\u00B0   x 2.5\u00B0     global
+
+3.  0.5\u00B0   x 0.625\u00B0   global
+4.  0.5\u00B0   x 0.625\u00B0   nested AS
+5.  0.5\u00B0   x 0.625\u00B0   nested EU
+6.  0.5\u00B0   x 0.625\u00B0   nested NA
+
+7   0.25\u00B0  x 0.3125\u00B0  global
+8.  0.25\u00B0  x 0.3125\u00B0  nested AF
+9.  0.25\u00B0  x 0.3125\u00B0  nested AS
+10. 0.25\u00B0  x 0.3125\u00B0  nested EU
+11. 0.25\u00B0  x 0.3125\u00B0  nested ME
+12. 0.25\u00B0  x 0.3125\u00B0  nested NA
+13  0.25\u00B0  x 0.3125\u00B0  nested OC
+14. 0.25\u00B0  x 0.3125\u00B0  nested SA
+15. 0.25\u00B0  x 0.3125\u00B0  nested RU
+
+16. 0.125\u00B0 x 0.15625\u00B0 global
+17. 0.125\u00B0 x 0.15625\u00B0 nested AF
+18. 0.125\u00B0 x 0.15625\u00B0 nested AS
+19. 0.125\u00B0 x 0.15625\u00B0 nested EU
+20. 0.125\u00B0 x 0.15625\u00B0 nested NA
+21. 0.125\u00B0 x 0.15625\u00B0 nested SA
+    """
+    print(msg)
+
+    while True:
+        try:
+            selection = int(input("Enter a selection >>> "))
+            if 1 <= selection <= 21:
+                break   # valid, exit loop
+            print("❌ Entry out of range. Try again.")
+        except ValueError:
+            print("❌ Not a number. Try again.")
+
+    return selection - 1
+
+
+def main():
+    """
+    Main program
+    """
+
+    # Display a list of grids and get the user's selection
+    selection = display_menu()
+
+    # Get the parameters that define the grid
+    grid_params = get_grid_parameters(selection)
+
+    # Create the grid object and print metadata
+    create_grid_and_print_info(grid_params)
+
+
+if __name__ == '__main__':
+    main()