ARBEJDE MED ZIP-FILER I PYTHON

Denne artikel forklarer, hvordan man kan udføre forskellige operationer på en zip-fil ved hjælp af et simpelt python-program. Hvad er en zip-fil? ZIP er et arkivfilformat, der understøtter tabsfri datakomprimering. Med tabsfri komprimering mener vi, at komprimeringsalgoritmen tillader de originale data at blive perfekt rekonstrueret ud fra de komprimerede data. Så en ZIP-fil er en enkelt fil, der indeholder en eller flere komprimerede filer, der tilbyder en ideel måde at gøre store filer mindre og holde relaterede filer sammen. Hvorfor har vi brug for zip-filer?

For at reducere krav til opbevaring.
For at forbedre overførselshastigheden i forhold til standardforbindelser.

For at arbejde med zip-filer ved hjælp af python vil vi bruge et indbygget python-modul kaldet zip-fil .

1. Udpakning af en zip-fil

Python

    # importing required modules   from   zipfile   import   ZipFile   # specifying the zip file name   file_name   =   'my_python_files.zip'   # opening the zip file in READ mode   with   ZipFile  (  file_name     'r'  )   as   zip  :   # printing all the contents of the zip file   zip  .  printdir  ()   # extracting all the files   print  (  'Extracting all the files now...'  )   zip  .  extractall  ()   print  (  'Done!'  )

The above program extracts a zip file named 'my_python_files.zip' in the same directory as of this python script. The output of above program may look like this: Arbejde med zip-filer i Python

Lad os prøve at forstå ovenstående kode i stykker:

```
from zipfile import ZipFile 
```
ZipFile is a class of zipfile module for reading and writing zip files. Here we import only class ZipFile from zipfile module.
```
with ZipFile(file_name 'r') as zip: 
```
Here a ZipFile object is made by calling ZipFile constructor which accepts zip file name and mode parameters. We create a ZipFile object in LÆSE tilstand og navngiv den som lynlås .
```
zip.printdir() 
```
printdir() metode udskriver en indholdsfortegnelse for arkivet.
```
zip.extractall() 
```
extractall() metode vil udtrække alt indholdet af zip-filen til den aktuelle arbejdsmappe. Du kan også ringe ekstrahere() method to extract any file by specifying its path in the zip file. For example:
```
zip.extract('python_files/python_wiki.txt') 
```
This will extract only the specified file. If you want to read some specific file you can go like this:
```
data = zip.read(name_of_file_to_read) 
```

2. Skrivning til en zip-fil

Overvej en mappe (mappe) med et sådant format: Arbejde med zip-filer i Python

Here we will need to crawl the whole directory and its sub-directories in order to get a list of all file paths before writing them to a zip file. The following program does this by crawling the directory to be zipped: Python

    # importing required modules   from   zipfile   import   ZipFile   import   os   def   get_all_file_paths  (  directory  ):   # initializing empty file paths list   file_paths   =   []   # crawling through directory and subdirectories   for   root     directories     files   in   os  .  walk  (  directory  ):   for   filename   in   files  :   # join the two strings in order to form the full filepath.   filepath   =   os  .  path  .  join  (  root     filename  )   file_paths  .  append  (  filepath  )   # returning all file paths   return   file_paths   def   main  ():   # path to folder which needs to be zipped   directory   =   './python_files'   # calling function to get all file paths in the directory   file_paths   =   get_all_file_paths  (  directory  )   # printing the list of all files to be zipped   print  (  'Following files will be zipped:'  )   for   file_name   in   file_paths  :   print  (  file_name  )   # writing files to a zipfile   with   ZipFile  (  'my_python_files.zip'    'w'  )   as   zip  :   # writing each file one by one   for   file   in   file_paths  :   zip  .  write  (  file  )   print  (  'All files zipped successfully!'  )   if   __name__   ==   '__main__'  :   main  ()

The output of above program looks like this: Arbejde med zip-filer i Python

Lad os prøve at forstå ovenstående kode ved at opdele i fragmenter:

```
def get_all_file_paths(directory): file_paths = [] for root directories files in os.walk(directory): for filename in files: filepath = os.path.join(root filename) file_paths.append(filepath) return file_paths 
```
First of all to get all file paths in our directory we have created this function which uses the os.walk() metode. I hver iteration føjes alle filer, der findes i den mappe, til en liste kaldet filstier . Til sidst returnerer vi alle filstierne.
```
file_paths = get_all_file_paths(directory) 
```
Here we pass the directory to be zipped to the get_all_file_paths() funktion og få en liste med alle filstier.
```
with ZipFile('my_python_files.zip''w') as zip: 
```
Here we create a ZipFile object in WRITE mode this time.
```
for file in file_paths: zip.write(file) 
```
Here we write all the files to the zip file one by one using skrive metode.

3. Henter alle oplysninger om en zip-fil

Python

    # importing required modules   from   zipfile   import   ZipFile   import   datetime   # specifying the zip file name   file_name   =   'example.zip'   # opening the zip file in READ mode   with   ZipFile  (  file_name     'r'  )   as   zip  :   for   info   in   zip  .  infolist  ():   print  (  info  .  filename  )   print  (  '  t  Modified:  t  '   +   str  (  datetime  .  datetime  (  *  info  .  date_time  )))   print  (  '  t  System:  tt  '   +   str  (  info  .  create_system  )   +   '(0 = Windows 3 = Unix)'  )   print  (  '  t  ZIP version:  t  '   +   str  (  info  .  create_version  ))   print  (  '  t  Compressed:  t  '   +   str  (  info  .  compress_size  )   +   ' bytes'  )   print  (  '  t  Uncompressed:  t  '   +   str  (  info  .  file_size  )   +   ' bytes'  )

The output of above program may look like this:

for info in zip.infolist():

Here infoliste() metoden opretter en instans af ZipInfo klasse, som indeholder alle oplysninger om zip-filen. Vi kan få adgang til alle oplysninger som sidste ændringsdato for filer filnavne system, hvorpå filer blev oprettet Zip-version størrelse af filer i komprimeret og ukomprimeret form osv. Denne artikel er bidraget af Nikhil Kumar . Opret quiz