nc2bmp

#!/usr/bin/env python

import netCDF4 as nc
from  PIL import Image
import numpy as np
from argparse import ArgumentParser


def get_field(filename, var, level=0, timestep=0):
    infile=nc.Dataset(filename,"r")
    data=np.squeeze(infile.variables[var])
    return data

def rescale_data(data, prescale_function=False):
    if prescale_function:
        data=prescale_function(data)
    dmin = data.min()
    dmax = data.max()
    data = ((data+dmin)/(dmax-dmin)*255).round().astype(np.uint8)
    return data

def store_image(data, filename, opts=False):
    result = Image.fromarray(data)
    result.save(filename)
    return 0



def parse_options():
    # initialize parser
    parser = ArgumentParser()
    parser.description = "Convert a netcdf field into a bmp image"
    # specify options
    parser.add_argument("-f" , "--filename", help = "filename", required = True)
    parser.add_argument("-n" , "--var_name", help = "variable name", required = True)
    parser.add_argument("-o" , "--bitmap_name", help = "filename for output, default VAR_FILENAME.bmp", default = None )
    parser.add_argument("-v", "--verbose", 
                        help='''Be verbose''', action="store_true")
    
    # run argparse
    options = parser.parse_args()
    return options  


def main():
    options = parse_options()
    data = get_field(options.filename, options.var_name)
    data = rescale_data(data)
    if options.bitmap_name:
        outname = options.bitmap_name
    else:
        outname = "%s_%s.bmp"%(options.filename[:-3], options.var_name)
    store_image(data, outname)
    
if __name__ == "__main__":
    main()