R, Python 분석과 프로그래밍의 친구 (by R Friend)

  (1) 압축 ZIP 파일 쓰기 (write)

import zipfile
import os

## change working directory
base_dir = '/Users/ihongdon/Downloads'
os.chdir(base_dir)

## check the current working directory
os.getcwd()

[Out] '/Users/ihongdon/Downloads'

## show the lists of files in the current working directory
os.listdir()

['sample_2.txt', 'sample_3.txt', 'sample_1.txt']

## (1) mode='w': to truncate and write a new file
myzip_w = zipfile.ZipFile('sample.zip', 'w')
myzip_w.write('sample_1.txt')

## You must call close() before exiting your program,
## or essential records will not be written.
myzip_w.close()

## ZipFile.is_zipfile(): Return True if a valid ZIP file exists.
zipfile.is_zipfile('sample.zip')

[Out] True

with zipfile.ZipFile('sample.zip', 'w') as myzip:
    myzip.write('sample_1.txt')
    myzip.close()

## (2) mode='x': to exclusively create and write a new file.
## if file refers to an existing file, a 'FileExistsError' will be raised.
myzip_x = zipfile.ZipFile('sample.zip', 'x')

[Out]
---------------------------------------------------------------------------
FileExistsError                           Traceback (most recent call last)
<ipython-input-7-bd84b411165c> in <module>
      1 ## (2) mode='x': to exclusively create and write a new file.
      2 ## if file refers to an existing file, a 'FileExistsError' will be raised.
----> 3 myzip_x = zipfile.ZipFile('sample.zip', 'x')

~/opt/anaconda3/lib/python3.8/zipfile.py in __init__(self, file, mode, compression, allowZip64, compresslevel, strict_timestamps)
   1249             while True:
   1250                 try:
-> 1251                     self.fp = io.open(file, filemode)
   1252                 except OSError:
   1253                     if filemode in modeDict:

FileExistsError: [Errno 17] File exists: 'sample.zip'

myzip_x = zipfile.ZipFile('sample2.zip', 'x')
myzip_x.write('sample_2.txt')
myzip_x.close()

myzip_x.namelist()

[Out] ['sample_2.txt']

## (3) mode='a': to append to an existing file.
myzip_a = zipfile.ZipFile('sample.zip', 'a')
myzip_a.write('sample_2.txt')
myzip_a.write('sample_3.txt')
myzip_a.close()

myzip_a.namelist()

[Out] ['sample_1.txt', 'sample_2.txt', 'sample_3.txt']

## (4) writing files to a zip file: with statement & for loop
file_list = ['sample_1.txt', 'sample_2.txt', 'sample_3.txt']

with zipfile.ZipFile('sample_all.zip', 'w') as myzip_all:
    for f in file_list:
        myzip_all.write(f)
        print(f, 'is written to myzip_all.zip')
    myzip_all.close()

[Out] 
sample_1.txt is written to myzip_all.zip
sample_2.txt is written to myzip_all.zip
sample_3.txt is written to myzip_all.zip

myzip_all.namelist()

[Out] ['sample_1.txt', 'sample_2.txt', 'sample_3.txt']

매개변수

설명

 compression

 compression은 자료를 압축 파일에 쓰기 위한 ZIP 압축 메소드이며, 기본 설정값은 ZIP_STORED 입니다.

Python 버전 3.1 부터 아래의 파일과 같은 객체를 지원합니다.

• zipfile.ZIP_STORED  (* default)
  
• zipfile.ZIP_DEFLATED
• zipfile.ZIP_BZIP2

Python 버전 3.3 부터는 ZIP_LZMA 객체를 지원합니다.

• zipfile.ZIP_LZMA
  

 allowZip64

 allowZip64=True (기본 설정) 이면 ZIP 파일 크기가 4GB를 넘을 경우 ZIP64 extensions 를 사용해서 ZIP 파일을 생성합니다.

 만약 allowZip64=False 설정인데 ZIP 파일 크기가 4GB를 넘을 경우에는 exception error 가 발생합니다.

 compresslevel

 compresslevel 매개변수는 자료를 압축할 수준을 지정할 때 사용합니다.

(compression 이 ZIP_STORED, ZIP_LZMA 일 경우에는 효과가 없으며, ZIP_DEPLATED, ZIP_BZIP2 에만 설정 가능합니다.)

• compression=ZIP_DEFLATED 일 경우 compresslevel=0~9 까지 설정 가능
  
• compression=ZIP_BZIP2 일 경우 compresslevel=1~9 까지 설정 가능
  

  (2) 압축 ZIP 파일 읽기 (read)

import pandas as pd

sample_1_df = pd.read_csv('sample_1.txt')
print(sample_1_df)

[Out]
   x1  x2  x3
0   1   2   3
1   4   5   6
2   7   8   9

  (3) 압축 ZIP 파일 이름(filename), 자료 리스트(namelist()), 파일 정보(getinfo) 보기

file_list = ['sample_1.txt', 'sample_2.txt', 'sample_3.txt']

with zipfile.ZipFile('sample_all.zip', 'w') as myzip_all:
    for f in file_list:
        myzip_all.write(f)
    myzip_all.close()

## ZipFile.is_zipfile(): Return True if a valid ZIP file exists.
zipfile.is_zipfile('sample_all.zip')

[Out] True

## ZipFile.filename: Name of the ZIP file
myzip_all.filename

[Out] 'sample_all.zip'

## file name lists of sample_all.zip
myzip_all.namelist()

[Out] ['sample_1.txt', 'sample_2.txt', 'sample_3.txt']

## ZipFile.getinfo(): Zip information about the archive member name.
myzip_all.getinfo('sample_1.txt')

[Out] <ZipInfo filename='sample_1.txt' filemode='-rw-r--r--' file_size=27>

  (4) 압축 ZIP 파일 해제하기 (extract)

## (4-1) ZipFile.extract()
## : extracting a member from the archive to the current working directory.
extract_path = '/Users/ihongdon/Downloads/sample_3'
zipfile.ZipFile('sample_all.zip').extract('sample_3.txt', path=extract_path)

[Out] '/Users/ihongdon/Downloads/sample_3/sample_3.txt'

os.listdir(extract_path)

[Out] ['sample_3.txt']

## (4-2) ZipFile.extractall()
## : extracting all members from the archive to the current working directory.
extractall_path = '/Users/ihongdon/Downloads/sample_all'
zipfile.ZipFile('sample_all.zip').extractall(extractall_path)

os.listdir(extractall_path)

[Out] ['sample_2.txt', 'sample_3.txt', 'sample_1.txt']

  (5) 웹에서 ZIP 파일 다운로드하여 압축 해제하기 (download and extract ZIP file)

## Download the movielens data from website url
import tensorflow.keras as keras
from zipfile import ZipFile
from pathlib import Path

import os

movielens_data_file_url = (
    "http://files.grouplens.org/datasets/movielens/ml-latest-small.zip"
)

movielens_zipped_file = keras.utils.get_file(
    "ml-latest-small.zip", movielens_data_file_url, extract=False
)

keras_datasets_path = Path(movielens_zipped_file).parents[0]
movielens_dir = keras_datasets_path / "ml-latest-small"

## Only extract the data the first time the script is run.
if not movielens_dir.exists():
    with ZipFile(movielens_zipped_file, "r") as zip:
        zip.extractall(path=keras_datasets_path) # extract all members in a ZIP file

print('datasets path:', keras_datasets_path)

[Out] datasets path: /Users/ihongdon/.keras/datasets

print(os.listdir(keras_datasets_path))

[Out] ['cowper.txt', 'reuters_word_index.json', 'imdb_word_index.json', 'flower_photos.tar.gz', 'cifar-10-batches-py', 'mnist.npz', 'ml-latest-small.zip', 'ml-latest-small', 'fashion-mnist', 'butler.txt', 'imdb.npz', 'cifar-10-batches-py.tar.gz', 'boston_housing.npz', 'creditcard.csv', 'creditcard.zip', 'derby.txt', 'train.csv', 'flower_photos', 'reuters.npz', 'fsns.tfrec']

os.listdir(movielens_dir)

[Out] ['links.csv', 'tags.csv', 'ratings.csv', 'README.txt', 'movies.csv']