writing unigrid to file

#Writing the output into a file
dat=data.flatten()
print("Writing ",fld," unigrid to file ...")
data=open(RDfile+'_'+field+'.txt', 'a')
for j in range(max(np.shape(dat))):
        data.write(str(dat[j]))
        data.write('\n')
data.close()
print("Unigrid data successfully written to "+RDfile+"_"+field+".txt.")