import glob

sciezka = 'scores/*.npz.bleu'

for plik in glob.glob(sciezka):

    with open(plik, 'r') as f:

        for linia in f.readlines():

            numer = float(linia[linia.find("=") + 1:linia.find(",")])

            if numer > 0:

                max_numer = numer

                max_numer_plik = plik

            f.close()

print(max_numer_plik)