[TOC]

writing file

using pickle

try:
  f = open(pickle_file, 'wb')
  save = {
    'train_dataset': train_dataset,
    'train_labels': train_labels,
    'valid_dataset': valid_dataset,
    'valid_labels': valid_labels,
    'test_dataset': test_dataset,
    'test_labels': test_labels,
    }
  pickle.dump(save, f, pickle.HIGHEST_PROTOCOL)
  f.close()
except Exception as e:
  print('Unable to save data to', pickle_file, ':', e)
  raise

write to file

f = open('myfile','w')
f.write('hi there\n') # python will convert \n to os.linesep
f.close() # you can omit in most cases as the destructor will call it  

file name

if not os.path.exists(filename):

get file info

statinfo = os.stat(filename)

concat directory + file name

image_file = os.path.join(folder, image)

list all files

files = os.listdir(folder)

list all directories

data_folders = [
    os.path.join(root, d) for d in sorted(os.listdir(root))
    if os.path.isdir(os.path.join(root, d))]

directory

if os.path.isdir(root)

file size differs

if statinfo.st_size == expected_bytes:
    print('Found and verified', filename)
  else:
    raise Exception(
      'Failed to verify ' + filename + '. Can you get to it with a browser?')
  return filename

extract zip files

zip_ref = zipfile.ZipFile(path_to_zip_file, 'r')
zip_ref.extractall(directory_to_extract_to) # only if destiation directory is different
zip_ref.close()  

extract tar files

tar = tarfile.open(filename)
sys.stdout.flush()
tar.extractall()
tar.close()