Python Pandas: Bucketing in python and calculating mean for a bucket

Code:

from pathlib import Path

files = Path(".").glob("1*.csv")
my_df_list = []

bins = [650,1000,1350,1700,2050,2400,2750,3000]
columns = ("650-1000","1000-1350","1350-1700","1700-2050","2050-2400","2400-2750","2750-3000")

for file in files:
    file_name = file.name
    file_id = file_name.replace("*.csv","")
    df = pd.read_csv(file_name)
    print(df.columns)
    bins = [650,1000,1350,1700,2050,2400,2750,3000]
    a_bins = df.B.groupby(pd.cut(df['A'],bins))
    a_bins = a_bins.agg([np.mean]).reset_index(drop=True)
    a_bins_df = a_bins.T.copy()
    a_bins_df.columns = columns
    a_bins_df.index = [file_id]
    my_df_list.append(a_bins_df)
df_total = pd.concat(my_df_list,axis=0)