CSV파일_xlsx파일변환

from tkinter import filedialog
from tkinter import messagebox
import openpyxl as xl

def choose():
    file_name1 = filedialog.askopenfilename(initialdir='path', title='select file', 
    filetypes=(('*csv', '*.csv'),('all files', '*.*')))
    global files
    files=file_name1
    if files == '':
                messagebox.showwarning("경고", "파일을 추가 하세요")
    input_entry.delete(0.0, END)
    input_entry.insert(INSERT, files)


def cha_csv_xl():
    wbc = xl.Workbook()
    ws = wbc.active
    with open(files, 'r', encoding='UTF8') as f:
        for row in csv.reader(f):
            ws.append(row)
    new_filesname=files[:-4]+'.xlsx'
    wbc.save(new_filesname)
    messagebox.showinfo("변경완료", "확인해 보세요")


ch_csvtoxl=LabelFrame(tab3, text='transform csv to xlsx')
ch_csvtoxl.grid(column=0, row=1, padx=8, pady=5)

chlb=Label(ch_csvtoxl, text="파일선택:",width=8).grid(column=0, row=0,sticky='W')
input_entry= Text(ch_csvtoxl, height=2, width=35, wrap=WORD)
input_entry.grid(column=1, row=0,sticky='W')

lbID4=Label(ch_csvtoxl, text="",width=1).grid(column=4, row=0,sticky='W')
b1 = Button(ch_csvtoxl,text="선택",width=16,command=choose).grid(column=1, row=1,sticky='W')
b2 = Button(ch_csvtoxl,text="변경",width=16,command=cha_csv_xl).grid(column=1, row=1,sticky='E')