ARBEIDE MED ZIP-FILER I PYTHON

Denne artikkelen forklarer hvordan man kan utføre ulike operasjoner på en zip-fil ved hjelp av et enkelt python-program. Hva er en zip-fil? ZIP er et arkivfilformat som støtter tapsfri datakomprimering. Med tapsfri komprimering mener vi at komprimeringsalgoritmen gjør at originaldata kan rekonstrueres perfekt fra de komprimerte dataene. Så en ZIP-fil er en enkelt fil som inneholder en eller flere komprimerte filer som tilbyr en ideell måte å gjøre store filer mindre og holde relaterte filer sammen. Hvorfor trenger vi zip-filer?

For å redusere lagringskravene.
For å forbedre overføringshastigheten over standardforbindelser.

For å jobbe med zip-filer ved hjelp av python vil vi bruke en innebygd python-modul kalt zip-fil .

1. Pakk ut 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: Arbeide med zip-filer i Python' title=

La oss prøve å forstå koden ovenfor 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 LESE modus og navngi den som zip .
```
zip.printdir()
```
printdir() metoden skriver ut en innholdsfortegnelse for arkivet.
```
zip.extractall()
```
extractall() metoden vil trekke ut alt innholdet i zip-filen til gjeldende arbeidskatalog. Du kan også ringe extract() 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. Skrive til en zip-fil

Tenk på en katalog (mappe) med et slikt format: Arbeide med zip-filer i Python' title=

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: Arbeide med zip-filer i Python' title=

La oss prøve å forstå koden ovenfor ved å dele inn 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 iterasjon legges alle filene som finnes i den katalogen til en liste kalt filstier . Til slutt returnerer vi alle filbanene.
```
file_paths = get_all_file_paths(directory)
```
Here we pass the directory to be zipped to the get_all_file_paths() funksjon og få en liste som inneholder 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. Få all informasjon 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('tModified:t' + str(datetime.datetime(*info.date_time))) print('tSystem:tt' + str(info.create_system) + '(0 = Windows 3 = Unix)') print('tZIP version:t' + str(info.create_version)) print('tCompressed:t' + str(info.compress_size) + ' bytes') print('tUncompressed:t' + str(info.file_size) + ' bytes')

The output of above program may look like this: ' title=

for info in zip.infolist():

Here infoliste() metoden oppretter en forekomst av ZipInfo klasse som inneholder all informasjon om zip-filen. Vi har tilgang til all informasjon som siste endringsdato for filene filnavnsystemet som filene ble opprettet på. Zip-versjonsstørrelsen på filer i komprimert og ukomprimert form osv. Denne artikkelen er bidratt av Nikhil Kumar . Lag quiz