每次迭代将一行写入文件而不覆盖python中的文件

Question

我已经在 Stackoverflow 上搜索了这个以及该主题的所有“重复项”，但似乎仍未得到答复。这些我都试过了：

尝试#1：

for word in header:
    writer.writerow([word]

从writing data from a python list to csv row-wise粘贴​​em>

尝试#2：

这个，应该很接近，但它有一个错误：

# Open a file in witre mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name


Pasted from <http://www.tutorialspoint.com/python/file_writelines.htm> 

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

seq = ["This is 6th line\n", "This is 7th line"]
# Write sequence of lines at the end of the file.
fo.seek(0, 2)
line = fo.writelines( seq )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(7):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

从http://www.tutorialspoint.com/python/file_writelines.htm粘贴​​em>

尝试#3：

>>>outF = open("myOutFile.txt", "w")
>>>for line in textList:
...    outF.write(line)
...    outF.write("\n")
>>>outF.close()

粘贴自http://cmdlinetips.com/2012/09/three-ways-to-write-text-to-a-file-in-python/

尝试#4：

with open('file_to_write', 'w') as f:
    f.write('file contents')

从Correct way to write line to file in Python粘贴​​em>

尝试#5：

这个在写入文件时使用附加..但它在每一行的末尾附加每一行。所以我很难把所有的行分开。

append_text = str(alldates)
with open('my_file.txt', 'a') as lead:
    lead.write(append_text)

从Python: Saving a string to file without overwriting file's contents粘贴​​em>

谁能帮我在不覆盖文件的情况下，如何在循环中每次迭代将换行的行写入文件？

Answer 1

data = [1,2,3,4,5]
with open('asd.txt', 'w') as fn:
    for i in data:
        fn.write(str(i) + '\n') # Add a \n (newline) so the next write will occure in the next line

asd.txt的内容：

1
2
3
4
5

如果您想附加到文件，请使用with open('asd.txt', 'a') as fn:

Answer 2

有两种方法可以做到这一点：

首先在输出行的末尾添加“\n”字符：

for x in row:
   writer.write(x + "\n")

第二次以追加模式打开文件，它将添加现有文本文件的行，但要小心。它不会覆盖文件：

fw = open(myfile.txt,'a')