import os

for root, dirs, files in os.walk ('A:/pycharm/study0722/data') :
    for f in files :
        print(f)
# ---------- 파일 목록 읽기 -------------

        os.chdir('A:/pycharm/study0722/data')
        dirextory = ('A:/pycharm/study0722/data')
        for file in dirextory :
            with open(file, 'r') as g :
                read_file = open_file.read()
                print(g)

# ------------ 여러파일 수정 실패 -----------------

import glob

list = glob.glob('A:/pycharm/study0722/data./*.txt')
for fn in list :
    with open(fn, 'r') as f:
        with open(fn.replace('txt', 'csv'), 'w') as f2 :
            for line in f:

                f2.write(line)

#----------------- 여러 파일 저장 (확인). 근데 내용이 아니라 파일명만 들어감.. ------------------


import glob

list = glob.glob('A:/pycharm/study0722/data./*.txt')
for fn in list :
    with open(fn, 'r') as f:
        with open(fn.replace('txt', 'csv'), 'w') as f2 :
            for line in f:
                tokens = line.split()
                year = int(tokens[0])
                month = int(tokens[1])
                day = int(tokens[2])
                tmax = float(tokens[3])
                tavg = float(tokens[4])
                tmin = float(tokens[5])
                rainfall = float(tokens[10])
                f2.write("{:d}, {:d}, {:d}, {:.1f}, {:.1f}, {:.1f}, {:.1f}".format(year, month, day, tmax, tavg, tmin, rainfall))

                f2.write(line)

# -----------여러 파일을 수정한 후 저장 하기 1 실패-----------------------



import os
output_dir = 'A:/pycharm/study0722/data'
for path, dirs, files in os.walk ('A:/pycharm/study0722/data') :
    for f in files:
        with open(os.join('A:/pycharm/study0722/data/',f), 'r') as fr:
            with open(os.path.join(output_dir,f),'w') as fo:
             fo.write(f)

#---------------- 여러 파일 저장하기 2 실패 --------------
#----------os.join이 없음.. (?)--------------