tags: python zip compression
title: Python Zip Files

The [docs](https://docs.python.org/3/library/zipfile.html)

```py
with ZipFile('spam.zip', 'w') as myzip:
    myzip.write('eggs.txt')
```

### Example
Extract one file (the first) from each .zip file.
```py
from zipfile import ZipFile
from glob import glob
import os
zs = glob("*.zip")

os.makedirs("samples",exist_ok=True)
for i,z in enumerate(zs):
  x = z.split(".")[0]
  with ZipFile(z,"r") as f:
    nl = f.namelist()
    n = nl[0]
    ofn = f"samples/{n}"
    with f.open(n,"r") as g:
      data = g.read()
    with open(ofn,"wb") as g:
      g.write(data)
    print(f"{i}/{len(zs)} {n}")
```
### Updating an archive
You need to write to a new archive, copying all those files you don't want to change.
This example modifies a single line in a single text file in a Reaper theme.
(I don't recommend actually running this. It is offered as example code.)
```py
#!/usr/bin/env python
import sys
from zipfile import ZipFile
import os
import re

args = sys.argv[1:]
try:
  zfn, ozfn, newsize = args
  newsize = int(newsize)
except ValueError:
  print(f"{sys.argv[0]} <zipfilename> <outzipfilename> <newsize>")
  exit(1)

fn = "Default_7.0_unpacked/rtconfig.txt"
with ZipFile(zfn,"r") as zf:
  with zf.open(fn,"r") as rt:
    rtd = rt.read()
lines = rtd.decode().splitlines()
for i,line in enumerate(lines):
  if "LayoutA-tcpLabelLength" in line:
    sep = "'Layout A - TCP Label Length'"
    l,r = line.split(sep,1)
    r = re.sub('\d+',str(newsize),r,count=1)
    line = sep.join((l,r))
    lines[i] = line
    break
else:
  print(f"Couldn't find the line to change")
  exit(2)
rtd = "\r\n".join(lines).encode()
with ZipFile(zfn,"r") as zfi:
  with ZipFile(ozfn,"w") as zfo:
    nl = zfi.namelist()
    for x in nl:
      if x == fn:
        zfo.writestr(fn,rtd,compresslevel=0)
      else:
        with zfi.open(x,"r") as f:
          data = f.read()
        with zfo.open(x,"w") as f:
          f.write(data)
print("Written",ozfn)
```