我如何在Python中指明字符串中的换行符,以便我可以将多行写入文本文件?


当前回答

\n分隔字符串的行。在下面的示例中,我一直在循环中写入记录。每条记录以\n分隔。

f = open("jsonFile.txt", "w")

for row_index in range(2, sheet.nrows):

  mydict1 = {
    "PowerMeterId" : row_index + 1,
    "Service": "Electricity",
    "Building": "JTC FoodHub",
    "Floor": str(Floor),
    "Location": Location,
    "ReportType": "Electricity",
    "System": System,
    "SubSystem": "",
    "Incomer": "",
    "Category": "",
    "DisplayName": DisplayName,
    "Description": Description,
    "Tag": tag,
    "IsActive": 1,
    "DataProviderType": int(0),
    "DataTable": ""
  }
  mydict1.pop("_id", None)
  f.write(str(mydict1) + '\n')

f.close()

其他回答

正如在其他回答中提到的:“新的行字符是\n。它在字符串中使用”。

我发现最简单易读的方法是使用“format”函数,使用nl作为新行名称,并将你想打印的字符串转换为你要打印的确切格式:

Python 2:

print("line1{nl}"
      "line2{nl}"
      "line3".format(nl="\n"))

Python 3:

nl = "\n"
print(f"line1{nl}"
      f"line2{nl}"
      f"line3")

这将输出:

line1
line2
line3

通过这种方式,它可以执行任务,并且还提供了代码的高可读性:)

'\n'也是一样,不过你可能不需要'\r'。在Java版本中使用它的原因是什么?如果你确实需要/想要它,你也可以在Python中以同样的方式使用它。

在Python 3中,该语言会在平台的原生表示中为你编码换行符。这意味着在Windows上是\r\n,而在成熟的系统上只是\n。

即使在U*x系统上,以文本模式读取Windows行结束符的文件也会返回正确的文本结果,即在\n字符之前的任何\r字符都会被无声地删除。

如果需要完全控制文件中的字节,则可以使用二进制模式。然后,每个字节恰好对应一个字节,Python不执行任何转换。

>>> # Write a file with different line endings, using binary mode for full control
>>> with open('/tmp/demo.txt', 'wb') as wf:
...     wf.write(b'DOS line\r\n')
...     wf.write(b'U*x line\n')
...     wf.write(b'no line')
10
9
7

>>> # Read the file as text
>>> with open('/tmp/demo.txt', 'r') as text:
...     for line in text:
...         print(line, end='')
DOS line
U*x line
no line

>>> # Or more demonstrably
>>> with open('/tmp/demo.txt', 'r') as text:
...     for line in text:
...         print(repr(line))
'DOS line\n'
'U*x line\n'
'no line'

>>> # Back to bytes!
>>> with open('/tmp/demo.txt', 'rb') as binary:
...     for line in binary:
...         print(line)
b'DOS line\r\n'
b'U*x line\n'
b'no line'

>>> # Open in binary, but convert back to text
>>> with open('/tmp/demo.txt', 'rb') as binary:
...     for line in binary:
...         print(line.decode('utf-8'), end='')
DOS line
U*x line
no line

>>> # Or again in more detail, with repr()
>>> with open('/tmp/demo.txt', 'rb') as binary:
...     for line in binary:
...         print(repr(line.decode('utf-8')))
'DOS line\r\n'
'U*x line\n'
'no line'

在Python中,你可以只使用换行符,即\n

Use:

"{}\n{}\n{}".format(
    "line1",
    "line2",
    "line3"
)

我个人更喜欢这种形式。