poem = '''\
Programming is fun
When the work is done
if you wanna make your work also fun:
use Python!
'''
f = open('poem.txt', 'w') # open for 'w'riting
f.write(poem) # write text to file
f.close() # close the file

How It Works: First, open a file by using the built-in open function and specifying the name of the file and the mode in which we want to open the file. The mode can be a read mode (’r’), write mode (’w’) or append mode (’a’). We can also specify whether we are reading, writing, or appending in text mode (’t’) or binary mode (’b’). There are actually many more modes available and help(open) will give you more details about them. By default, open() considers the file to be a ’t’ext file and opens it in ’r’ead mode. In our example, we first open the file in write text mode and use the write method of the file object to write to the file and then we finally close the file.

上面的例子来自Swaroop C H编写的《A Byte of Python》一书。 swaroopch.com

序列化列表到文本文件与逗号分隔值

mylist = dir()
with open('filename.txt','w') as f:
    f.write( ','.join( mylist ) )

使用Python 3和Python 2.6+语法:

with open(filepath, 'w') as file_handler:
    for item in the_list:
        file_handler.write("{}\n".format(item))

这是平台独立的。它还使用换行符结束最后一行，这是UNIX的最佳实践。

从Python 3.6开始，"{}\n".format(item)可以用f-string替换:f"{item}\n"。

file.write('\n'.join(list))

如果在python3上，还可以使用print函数，如下所示。

f = open("myfile.txt","wb")
print(mylist, file=f)

还有另一种方式。使用simplejson序列化为json(在python 2.6中包含为json):

>>> import simplejson
>>> f = open('output.txt', 'w')
>>> simplejson.dump([1,2,3,4], f)
>>> f.close()

如果你检查output.txt:

[1, 2, 3, 4]

这很有用，因为它的语法是python的，它是人类可读的，并且它可以被其他语言的其他程序读取。