acc_number     taxi
YP_001378452 2345
YP_001650052 5678
YP_009446812 5435
YP_002192894 7890

Nothing  cluster         species     target          score
7101    cluster_000001  species1    YP_001378452.1  31.7
50457   cluster_000001  species2    YP_001650052.1  27.9
48798   cluster_000001  species3    YP_002192894.1  34.5
8514    cluster_000001  species4    YP_009446812.1  28.9

TAXID=pd.read_table("/pathtoTAXID.txt",header=0)
blast=pd.read_table("/pathtoblast.txt",header=0)


for i in blast["target"]:
    if i in TAXID["acc_number"] without .1:
        add TAXID[taxi] in the line of the blast

for i in blast["target"]:
    print(TAXID.loc[TAXID["Acc_number"] == i.split('.')[0]][1])

df2['taxi']=df2.target.str.split(".").str[0].map(dict(zip(df1.acc_number,df1.taxi)))