您不能将列添加到现有的CSV文件中；恐怕您将不得不重写整个文件。
您可以使用以下上下文管理器来简化文件的替换：
from contextlib import contextmanagerimport ioimport os@contextmanagerdef inplace(filename, mode='r', buffering=-1, encoding=None, errors=None, newline=None, backup_extension=None): """Allow for a file to be replaced with new content. yields a tuple of (readable, writable) file objects, where writable replaces readable. If an exception occurs, the old file is restored, removing the written data. mode should *not* use 'w', 'a' or '+'; only read-only-modes are supported. """ # move existing file to backup, create new file with same permissions # borrowed extensively from the fileinput module if set(mode) & set('wa+'): raise ValueError('only read-only file modes can be used') backupfilename = filename + (backup_extension or os.extsep + 'bak') try: os.unlink(backupfilename) except os.error: pass os.rename(filename, backupfilename) readable = io.open(backupfilename, mode, buffering=buffering, encoding=encoding, errors=errors, newline=newline) try: perm = os.fstat(readable.fileno()).st_mode except OSError: writable = open(filename, 'w' + mode.replace('r', ''), buffering=buffering, encoding=encoding, errors=errors, newline=newline) else: os_mode = os.O_CREAT | os.O_WRonLY | os.O_TRUNC if hasattr(os, 'O_BINARY'): os_mode |= os.O_BINARY fd = os.open(filename, os_mode, perm) writable = io.open(fd, "w" + mode.replace('r', ''), buffering=buffering, encoding=encoding, errors=errors, newline=newline) try: if hasattr(os, 'chmod'): os.chmod(filename, perm) except OSError: pass try: yield readable, writable except Exception: # move backup back try: os.unlink(filename) except os.error: pass os.rename(backupfilename, filename) raise finally: readable.close() writable.close() try: os.unlink(backupfilename) except os.error: pass将此与
csv模块一起使用以添加列：
with inplace(csvfilename, 'rb') as (infh, outfh): reader = csv.reader(infh) writer = csv.writer(outfh) for row in reader: row += ['new', 'column'] writer.writerow(row)
