BACKGROUND:
==========
The script plot_grid_to_grid.py generates png plots of the raw variables and their corresponding diff from the output file generated by the MET grid-stat tool. 



Pre-requisite:
=============
        1) The user must configure the following nc_pair_flags to the following:
           -latlon=TRUE
           -raw=TRUE
           -diff=TRUE
           to generate the output netcdf files that contain the expected matched
           pairs output for this plotting script.
         2) Python modules required:
           -Cartopy
           -matplotlib
           -netCDF4

What to specify:
===============
In the grid.yaml configuration file, the user specifies the following:
 -input directory
 -output directory
 -and for each variable of interest:
    - the variable name (e.g. TMP, UBAR, VBAR, etc.)
    - the netcdf fcst variable (as indicated from performing 'ncdump' on the netcdf file
    - the netcdf obs variable
    - the title for the obs plot 
    - the title for the fcst plot  


What is created:
===============
For each variable-level combination, three plots are generated:
	-a contour plot of the fcst
	-a contour plot of the obs
	-a contour plot of the diff


Example data:
============
for the host 'kiowa', there is data that exists to run this script "as checked out"
The sample data is located at /d1/projects/METplus/METplus_Plotting_Data/grid_to_grid

How to run:
==========
set your PYTHONPATH to point to your $USER/METplotpy directory

run the following on the command line:
python plot_grid_to_grid.py grid.yaml

The simplest way to run the script is to cd to the directory METplotpy/metplotpy/contributed/grid_to_grid/
and enter the following;

python plot_grid_to_grid.py grid.yaml

You will see output messages such as the name of the png files that are being created. The files are saved to the output directory 
that was specified in the script.  
