Pythonでcsvファイルを読み書きする

from tkinter import filedialog
typ = [('','*.csv')]
dir = r'C:\work'
csv_file_name = filedialog.askopenfilename(filetypes = typ , initialdir = dir)
print(csv_file_name)

import numpy as np
data = np.loadtxt(csv_file_name, delimiter = ",", dtype = "unicode")

H_Username = data[0][0]
print(H_Username)
H_Password = data[0][1]
print(H_Password)
H_AccesskeyID = data[0][2]
print(H_AccesskeyID)
H_Secretaccesskey = data[0][3]
print(H_Secretaccesskey)
H_Consoleloginlink = data[0][4]
print(H_Consoleloginlink)

B_Username = data[1][0]
print(B_Username)
B_Password = data[1][1]
print(B_Password)
B_AccesskeyID = data[1][2]
print(B_AccesskeyID)
B_Secretaccesskey = data[1][3]
print(B_Secretaccesskey)
B_Consoleloginlink = data[1][4]
print(B_Consoleloginlink)

import numpy as np 
list_rows = [[H_Username,H_Password,H_AccesskeyID,H_Secretaccesskey,H_Consoleloginlink],
[B_Username,B_Password,B_AccesskeyID,B_Secretaccesskey,B_Consoleloginlink]]
np.savetxt(csv_file_name, list_rows, delimiter =",",fmt ='%s')