Step-by-step guide
Suppose the we have a GRIB file, and we want to use some NumPy routines to manipulate the data values, and then write the result back to a GRIB file. The following Python code shows how to do this:
import metview as mv
import numpy as np
g = mv.read("mydata.grib")[0] # work on the first field only
vals = np.reciprocal(g.values())
g = g.set_values(vals)
mv.write('recip.grib', g)